Yet Another Cycling Forum

General Category => Freewheeling => Topic started by: McWheels on February 24, 2018, 08:52:07 pm

Title: Bike Design
Post by: McWheels on February 24, 2018, 08:52:07 pm
What's changed in bike design since ... forever, that makes the bike itself safer? I wouldn't count accessories as those would apply to any design (lights, helmets, hi-viz etc).

And no, this isn't a Recumbent tirade, so don't react that way   :-*

And it's starting in America, so don't feel too threatened by it immediately either. [Second guessing the psychology of DF riders is fun though.  O:-)]

http://safercycling.org/ (http://safercycling.org/)

For those wanting a bit more background, click forward to 1:09.20 and you get a decent introduction.
https://www.youtube.com/watch?v=pGpUPNYcLXM&t=3353s (https://www.youtube.com/watch?v=pGpUPNYcLXM&t=3353s)

The question that comes out of this, though, is what Corporates do we know that it suits to support this idea?
Title: Re: Bike Design
Post by: Jakob W on February 24, 2018, 10:08:40 pm
Infrastructure, infrastructure, infrastructure. Bikes are plenty safe enough as they are, and anything else is fiddling around the edges. The only people with a vested interest in suggesting otherwise are snake-oil salespeople and the motor industry.
Title: Re: Bike Design
Post by: grams on February 24, 2018, 10:35:30 pm
"It has not undergone the same rigorous crash-testing and safety improvements as the automobile. This may be why only 14 million Americans ride their bike at least twice per week."

Are they seriously suggesting designing a "bicycle" that can protect the occupant from a collision with the thing most likely to hit it - an automobile? Good luck with that.
Title: Re: Bike Design
Post by: Kim on February 24, 2018, 11:05:36 pm
If you exclude recumbent geometry (covered in the other thread (https://yacf.co.uk/forum/index.php?topic=106991.0)), you're down to things like improved and/or more reliable brakes.  So alloy rims and disc brakes, I suppose.  I don't think anything revolutionary (rather than evolutionary) has happened in tyres since they went pneumatic.

I wouldn't really count lights as accessories - at least on bikes designed as a means of transport rather than a piece of sports equipment.  In which case LEDs have made a real difference to performance and reliability, but it's debatable how much of a safety benefit that actually gives (there being minimal evidence that lights reduce collisions with motor vehicles, and being able to see better in the dark generally just means you can ride faster for the same risk level).

You could argue that innovative bike designs make cycling appealing/practical/accessible to more people, leading to an indirect safety benefit through normalisation of cycling and the safety-in-numbers effect.  So potentially everything from cargo trikes through Bromptons to the latest carbon bling for MAMILs to willy-wave over.  I reckon electric assist is the next big thing in this respect.  (Infrastructure would do more than all these combined, but that's engineering the environment, not the cycle.)
Title: Re: Bike Design
Post by: McWheels on February 25, 2018, 06:54:57 pm
I think I've got 2 points to make about the replies, the latter also being about where I was trying to get the conversation going. All are linked, so let's have a go.

1. Assumptions about Infrastructure being the main effort mirror the road safety establishment as it was from the 1920s ref car safety. Their take was the 3Es, Education, Enforcement, and Engineering. First 2 were about the driver, and the third about the road. We do bang on about those, and they have their place for sure. But we ignore an aspect [bike design] we might be able to improve on, no?

2. Not sure the bike can protect a person from a 50mph side-swipe, but there are various common 'failure modes' of when and how people come off bikes or hit/are hit by something. I've had my fill on DF offs and they nearly all have a common outcome of trying to avoid head on concrete from height. Bents have different angles and shapes to deal with, so the scientific rigour could well be applied there with the right historical data feeding the tests. We might end up somewhere totally different to either, that's the fun of it.
Title: Re: Bike Design
Post by: mattc on February 25, 2018, 07:04:36 pm
They are considerably more reliable, faster and cheaper now, than in any previous decade.

So it is easier than ever to get the health benefits.

The worst thing you can do for your health is NOT ride a bike (even when you include the stats for accidents) :)
Title: Re: Bike Design
Post by: Jakob W on February 25, 2018, 07:40:33 pm
I'm not sure the comparison between cars and bikes is a particularly good one; the obvious difference being that, with the various propulsive improvements over the last century, cars can now weigh what, 3? 4? times what they used to at greater P/W, and that leaves a lot of space for safety equipment. With human power limited to 100-150W (assuming we're talking about mass cycling here; and if not, why bother?), even the efficiency gains from recumbency are unlikely to give you much of a power budget for active safety systems. And this ignores issues of cost, never mind the (admittedly possibly niche) philosophical appeal of the bicycle's simplicity.

The point about whether recumbent geometry is safer is potentially an interesting one: does the lower position more than compensate for the greater KE of the faster machine? (Though I will say you might get greater engagement with this point when not starting out with a good giggle at the psychological hangups of the poor benighted DF rider.)

Nonetheless, I would stand by the infrastructure point; Dutch cycling KSI rates are AIUI pretty negligible, though they start to rise in the elderly, who are more likely to fall off their bikes. This might be something to look at, but as a trade-off the net health effect of increased cycling rates is still overwhelmingly positive.
Title: Re: Bike Design
Post by: Kim on February 25, 2018, 08:02:48 pm
The point about whether recumbent geometry is safer is potentially an interesting one: does the lower position more than compensate for the greater KE of the faster machine?

I don't think it's so much height above the ground, as the way the recumbent geometry becomes unstable in crashes:  DFs are prone to chuck you over the bars so you land on your face, or your outstretched arm, leading to the classic broken wrists and collar bones.  Recumbents are more likely to slide out sideways, so you hit the ground sooner at lower vertical speed, typically leading to bruised hips and elbows and a whole load of road rash.

That broad difference aside, what I can see us learning from crash testing is the more subtle stuff.  How to design things like pedals and handlebars so you don't get tangled up in the bike during a crash, for example.  Or maybe - given that most cycle accidents result in only minor injuries - design tweaks that don't improve rider safety, but usefully reduce damage to the bike itself.   (Azub's USS handlebars that rotate around the bike's long axis on side impact come to mind.)
Title: Re: Bike Design
Post by: mrcharly-YHT on February 25, 2018, 08:12:38 pm
Brakes are a lot better.

Anyone here used brakes on chromed rims in the wet?

Modern LED lights are a huge improvement. Being able to see potholes, kerbs, etc are a big advantage in avoiding accidents.


I stopped listening to the video when he started going on about the UCI and recumbents. You are never going to fit recumbents on the underground, on buses. I suspect this guy has never seen a Brompton, for example.
Title: Re: Bike Design
Post by: Jakob W on February 25, 2018, 08:31:03 pm
Presumably darksiders are able to brake at higher Gs without going over the bars? In the dry I can see that being a safety benefit.
Title: Re: Bike Design
Post by: Kim on February 25, 2018, 09:27:39 pm
Presumably darksiders are able to brake at higher Gs without going over the bars? In the dry I can see that being a safety benefit.

Yes.  Although they're not always completely immune.  Tadpole trikes will try to embed their chainring in the tarmac, which is mostly harmless (unless there isn't a chainring guard).  I once properly endoed my Streetmachine in an emergency stop;  I landed neatly on my feet with the bike collapsing awkwardly behind me.

If the weight distribution isn't conducive to endoing, the front wheel(s) will eventually skid and on a bike that tends to mean you go down sideways and some of your skin comes off.

TBH, I think the superior braking tends to lead to risk compensation, by way of higher speeds.  Or, to put it another way, when I get on an upright after prolonged recumbent riding, it takes a while to get over the feeling that I'm going to land on my face as soon as I touch the front brake.
Title: Re: Bike Design
Post by: Kim on February 25, 2018, 09:38:38 pm
I stopped listening to the video when he started going on about the UCI and recumbents. You are never going to fit recumbents on the underground, on buses. I suspect this guy has never seen a Brompton, for example.

AIUI this guy is in the industry (ETA: He appears to be one of the founders of Cruzbike), and it's therefore entirely reasonable that he talk about recumbents in a video about recumbent cycling.

I don't think there's anything unreasonable about promoting recumbents in contexts where they're practical.  Why shouldn't recumbent riders have race categories to compete in?  They're excellent for touring and endurance riding.  They're the only option for some people with disabilities.  They can be awesome fun.  It doesn't matter that it's easier to make a good folding bike with a saddle and upright riding position, or that DFs are better for off-roading, or that some 'bents are a complete pain to transport under anything but their own power.  Best tool for the job just means you need a wider variety of tools.

The idea that you might be able to sell the idea of recumbent (or some other unconventional geometry) cycling to people based on the bikes being safer than a functionally equivalent upright isn't entirely stupid (just IMHO wildly optimistic).  But in order to do that, you first need some evidence, which is what he seems to be proposing.  Sure, why not?  Meh.
Title: Re: Bike Design
Post by: jsabine on February 26, 2018, 12:30:39 am
The idea that you might be able to sell the idea of recumbent (or some other unconventional geometry) cycling to people based on the bikes being safer than a functionally equivalent upright isn't entirely stupid (just IMHO wildly optimistic). 

Surely the whole DF industry is founded on the idea that the Safety Bicycle has a fundamentally safer geometry - than the Ordinary, admittedly, but still ...
Title: Re: Bike Design
Post by: Mr Larrington on February 26, 2018, 07:28:33 am
Someone did once start a business to make a conversion kit to turn a Brompton into a recumbent.  Folded, it was scarcely any bigger than the standard item, and a quick spin around the block outside Bikefix showed it to ride surprisingly well too, bearing in mind that I was wearing the wrong shoes and the bike's owner is about a foot shorter than me.  But they weren't able to sell enough to make a go of it.
Title: Re: Bike Design
Post by: Kim on February 26, 2018, 01:06:30 pm
The idea that you might be able to sell the idea of recumbent (or some other unconventional geometry) cycling to people based on the bikes being safer than a functionally equivalent upright isn't entirely stupid (just IMHO wildly optimistic). 

Surely the whole DF industry is founded on the idea that the Safety Bicycle has a fundamentally safer geometry - than the Ordinary, admittedly, but still ...

Sure, but safety bicycles are also easier to ride and allow for higher gain ratios than ordinaries without resorting to ergonomically silly crank lengths, as well as being more conducive to adaptation for carrying luggage.  Perhaps those practical advantages were more of a driving force than the safety benefits?
Title: Re: Bike Design
Post by: Kim on February 26, 2018, 01:19:02 pm
Someone did once start a business to make a conversion kit to turn a Brompton into a recumbent.  Folded, it was scarcely any bigger than the standard item, and a quick spin around the block outside Bikefix showed it to ride surprisingly well too, bearing in mind that I was wearing the wrong shoes and the bike's owner is about a foot shorter than me.  But they weren't able to sell enough to make a go of it.

I've seen pictures, and it's impressive.  I suppose the problem is that recumbent-aware Brompton enthusiasts (there does seem to be quite a lot of overlap) are happy for the Brompton to be their token upwrong, because (assuming you have the choice) the upright position is actually quite good for short-distance city riding.
Title: Re: Bike Design
Post by: Ian H on February 26, 2018, 02:35:17 pm
...design tweaks that don't improve rider safety, but usefully reduce damage to the bike itself.   (Azub's USS handlebars that rotate around the bike's long axis on side impact come to mind.)

A lot of people seem to have forgotten, or don't know, the trick of not over-tightening stems and bars, so that they will move in a crash.
Title: Re: Bike Design
Post by: asterix on February 26, 2018, 03:00:45 pm
Brakes are a lot better.

Anyone here used brakes on chromed rims in the wet?

..

They worked well enough when the water had been shed, which obviously could give a very long stopping distance!  In town, the trick was to keep the pads as close to the rim as possible when riding to keep them dry/warm as possible.  People complain about cantis but I have made some very impressive emergency stops with ordinary Shimano cantis with decent blocks.

A problem that bikes used to suffer from was shimmy.  For years I endured a 1985 tourer that could suffer from it and at last the only component left from the original were the Campag hubs which were eventually ditched to switch from freewheel to cassette hubs.  Once I'd got modern hubs the bike never shimmied again.

Other than all the above, I'd say it's not really down to bike design, more about improving the road environment and rider competence, both to ride the bike and keep it maintained properly.

Quote
A lot of people seem to have forgotten, or don't know, the trick of not over-tightening stems and bars, so that they will move in a crash.

 :o
Title: Re: Bike Design
Post by: Karla on February 26, 2018, 03:36:01 pm
Just make sure you avoid castration shifters

(http://www.m-gineering.nl/vwijk8.jpg)
Title: Re: Bike Design
Post by: cycleman on February 26, 2018, 07:46:40 pm
Which are a way of encouraging safe cycling in the same way a spike on the steering wheel would work for car's  ;)
Title: Re: Bike Design
Post by: McWheels on February 27, 2018, 09:30:39 pm
For safety bicycle you could read modesty bicycle, since ladies couldn't possibly be expected to endure such heights and speeds and potential ankle-flashing on an Ordinary. And then pneumatic tyres were invented and suddenly you didn't need an Ordinary to go fast.
Title: Re: Bike Design
Post by: Kim on February 27, 2018, 09:35:43 pm
To be fair, the ankle-flashing problem is even worse on recumbents.  Attempt to ride one of those without the aid of rational dress and you're liable to impair your (but unfortunately not everyone else's) vision, and/or suffer the worst kind of bee attack.   :hand:

The modesty bicycle is clearly the optimal design in that respect, unless you include the unicycle-concealed-beneath-layers-of-crinolines option.
Title: Re: Bike Design
Post by: LEE on February 27, 2018, 09:37:54 pm
As mentioned before:

Braking
Lighting
Tyres

Apart from that there's a damn good reason why the design hasn't changed in 100 years. They got it right*

*Most of know someone who has ridden about 150,000 miles in 3 years on one.  There can't be much wrong with the design because that's more than 15 years driving for me.
Title: Re: Bike Design
Post by: Kim on February 27, 2018, 09:44:16 pm
That's perilously close to the "somebody's done PBP on one" argument, thobut.   :D
Title: Re: Bike Design
Post by: joy of essex on February 28, 2018, 07:27:09 am
Looking back on 50 years of riding I would say that the improvements that made a difference  to safety are lights, brakes, rim materials and so  forth.

Bike design and geometry are another factor.  In my view , a safer bike  would be  a tourer , roadster, Raleigh 20 or a 1st generation MTB.
But the industry often only offers  the new cyclist  a Porsche when  what the person  need a Morris Minor
Title: Re: Bike Design
Post by: mrcharly-YHT on February 28, 2018, 09:45:02 am
Looking back on 50 years of riding I would say that the improvements that made a difference  to safety are lights, brakes, rim materials and so  forth.

Bike design and geometry are another factor.  In my view , a safer bike  would be  a tourer , roadster, Raleigh 20 or a 1st generation MTB.
But the industry often only offers  the new cyclist  a Porsche when  what the person  need a Morris Minor
Very true - but if you go to a 'cycling' city like York, you see a lot of cargo bikes, trailers etc (not so many Helios, although I've seen one around). These are all good designs.

I think maybe good hub gears and hub brakes that work in all weathers should be added to the list. Although these existed in days of yore, weight has come down a lot and power of brakes has gone up.
Title: Re: Bike Design
Post by: Karla on February 28, 2018, 11:57:19 am
Bike design and geometry are another factor.  In my view , a safer bike  would be  a tourer , roadster, Raleigh 20 or a 1st generation MTB.
But the industry often only offers  the new cyclist  a Porsche when  what the person  need a Morris Minor

Wouldn't it be nice if everyone rode an old boring person's bike, eh?  That way they might become old boring people faster.
Title: Re: Bike Design
Post by: DuncanM on February 28, 2018, 12:06:45 pm
Try riding a bike with rod brakes (and chromed rims) in the wet. Just don't go anywhere where you actually need to stop in less than 20 yards. Or go downhill!

IMO modern bicycles are fundamentally pretty safe. It's all the traffic around them that is the problem.
Title: Re: Bike Design
Post by: McWheels on March 04, 2018, 08:55:45 pm
I agree most bikes don't break catastrophically that often, and certainly not ones you pay a decent amount for. Structurally not much goes wrong.

The only thing we've ever known in our lifetime is the DF. Perhaps we should know more about it?
Title: Re: Bike Design
Post by: mrcharly-YHT on March 05, 2018, 01:01:56 pm
The only thing we've ever known in our lifetime is the DF. Perhaps we should know more about it?
Eh?
This from a person with a reference to a Cuzbike in their sigline?

One of the great manufacturing successes in the UK is the Brompton. That isn't a diamond frame. It is much imitated.

DF is hardly 'the only thing we've ever known'.

I'd agree there are very limited variations in riding position, but that is a function of the shape of the human body.
Title: Re: Bike Design
Post by: mzjo on March 07, 2018, 05:41:04 pm
The only useful way of improving safety is by increasing everybody's sense of self-preservation. While all the improvements to vehicle and environment work to reduce awareness of danger and the sense of self-preservation that goes with it, the benefits of the improvements will never add up to reasonable expectations of reducing accidents. The only difficulty is how one convinces well-sheltered car drivers that their lives are at risk (perhaps the best advance in road safety will be achieved by compulsary arms and weapons training for cyclists).
Title: Re: Bike Design
Post by: Socks on March 07, 2018, 07:32:13 pm
The only useful way of improving safety is by increasing everybody's sense of self-preservation. While all the improvements to vehicle and environment work to reduce awareness of danger and the sense of self-preservation that goes with it, the benefits of the improvements will never add up to reasonable expectations of reducing accidents.

Seems to me that we're better off than we've ever been in relation to bike design and options:

- plastic (sorry - carbon) frames and standard components at very reasonable prices
- good quality folding bikes such as Bromton, Dahon etc
- off-road options
- recumbent bikes and trikes
- electric assist

So why aren't more people cycling .....
Title: Re: Bike Design
Post by: zigzag on March 07, 2018, 08:10:03 pm
the guys in the video talk about recumbents as if they are better and safer than df bikes in all scenarios. it's not as simple as that - df bikes are more manouvrable, easier to handle (especially on loose surfaces), safer in city traffic as you can stand up and see over the roofs of most cars, safer because the legs and pedals which can be covered in reflective gear is very eye-catching at night (not the case on recumbents). also - one big safety feature of df bikes is the ability to bunny hop obstacles and holes on the road; i'd have wrecked several recumbents that way throughout my cycling career.
regarding riding in a group - imagine there is a pile-up in a recumbent peloton. what's the probability of following rider's chainrings/pedals/cranks hitting the front rider's head or shoulders at full force causing serious injuries?
i can see the advantages of recumbents too, but they are too specific and niche to become widely accepted as a mode of transport and included in cycling sport.
Title: Re: Bike Design
Post by: Karla on March 07, 2018, 09:39:46 pm
It does all read like yet another recumbentist superiority complex.  That's hardly surprising though.
Title: Re: Bike Design
Post by: Mr Larrington on March 08, 2018, 11:52:10 am
Not much you can do about recumbent cranks but AFAIK all recumbent race organisers have mandated chainring guards on unfaired machines with the cranks out front for a couple of decades now. Probably prompted by Axel Fehlau getting a chainring in his ear during the crits at the 1993 Europeans.  He got back on and deprived me of a place in the final with a spot of last-corner insanity, the git.
Title: Re: Bike Design
Post by: Kim on March 08, 2018, 01:33:45 pm
I've got a leg that suggests chainring guard technology has room for improvement...
Title: Re: Bike Design
Post by: McWheels on March 10, 2018, 01:12:03 pm

I'd agree there are very limited variations in riding position, but that is a function of the shape of the human body.

You forgot Moulton, also banned by UCI, but still the same riding position.

And that function is your assumption. Always* like this, therefore like this always.

* Not really.
Title: Re: Bike Design
Post by: mrcharly-YHT on March 10, 2018, 01:39:26 pm

I'd agree there are very limited variations in riding position, but that is a function of the shape of the human body.

You forgot Moulton, also banned by UCI, but still the same riding position.

And that function is your assumption. Always* like this, therefore like this always.

* Not really.
Then you invent some more (practical) riding positions.

It was *you* that said
Quote
The only thing we've ever known in our lifetime is the DF.
Now you are mentioning Moultons? Don't they kind of prove my point, that there are alternatives to the DF?
Title: Re: Bike Design
Post by: McWheels on March 11, 2018, 12:15:39 pm
I think you've rather missed the point.  I think we can take DF as shorthand for upright position in all its forms. This is about the normative riding position, and what we know about it. You've provided useful scrutiny all the same, since this was in danger of becoming about recumbent vs upright, and that's not the point at all.

If we go back to what was originally posited, is it worthwhile scientifically investigating the benefits and consequences of being upright? And once we know a bit more, what do we do with that information? Is the general confirmation bias too strong?
Title: Re: Bike Design
Post by: Kim on March 11, 2018, 01:02:12 pm
I think you've rather missed the point.  I think we can take DF as shorthand for upright position in all its forms. This is about the normative riding position, and what we know about it.

I thought it was about safety aspects of bike design?  I'd suggest that there may well be safety differences between a DF, a step-through frame and a small-wheeled bike with the same upright riding position, and that that there may well be safety differences between different kinds of recumbents with the same riding position.

Given that riding position tends to be dictated by what the bike's being used for, (being able to see where you're going, ease of starting/stopping, aerodynamic efficiency, ability to shift your bodyweight around, that sort of thing), it's the decisions that come after that (eg. what type of handlebars, braking systems, how exposed the transmission is) that have the most scope for being influenced by safety.

If safety were the only concern, we'd all be riding tadpole trikes.
Title: Re: Bike Design
Post by: tatanab on March 11, 2018, 01:32:18 pm
If safety were the only concern, we'd all be riding recumbent tadpole trikes.
FTFY
Title: Re: Bike Design
Post by: mrcharly-YHT on March 11, 2018, 01:39:30 pm
I think you've rather missed the point.  I think we can take DF as shorthand for upright position in all its forms. This is about the normative riding position, and what we know about it.

I thought it was about safety aspects of bike design?  I'd suggest that there may well be safety differences between a DF, a step-through frame and a small-wheeled bike with the same upright riding position, and that that there may well be safety differences between different kinds of recumbents with the same riding position.

Given that riding position tends to be dictated by what the bike's being used for, (being able to see where you're going, ease of starting/stopping, aerodynamic efficiency, ability to shift your bodyweight around, that sort of thing), it's the decisions that come after that (eg. what type of handlebars, braking systems, how exposed the transmission is) that have the most scope for being influenced by safety.

If safety were the only concern, we'd all be riding tadpole trikes.
Quite

It is somewhat ridiculous to say that "all upright riding positions are the same".

Riding down on tri bars on a very low time-trial bike is very very different from riding a sit-up city bike, to take two extremes. I would not like to ride the city bike down a mountain col, give me a race bike for that, please (and I'm talking from a position of safety here, not about riding faster).

If we assume poor road surfaces, then that has to be considered in bike design. Small wheels do not cope as well as large wheels when riding through deep potholes. Are we discussing riding in heavy traffic?

Choose the bike for the circumstances.
Title: Re: Bike Design
Post by: Kim on March 11, 2018, 02:07:04 pm
Riding down on tri bars on a very low time-trial bike is very very different from riding a sit-up city bike, to take two extremes. I would not like to ride the city bike down a mountain col, give me a race bike for that, please (and I'm talking from a position of safety here, not about riding faster).

If we're playing that game I think I'd prefer the upright city bike, assuming it was a decently made German-style one with proper brakes.  The about-to-land-on-your-face factor of DF racing bikes is terrifying downhill, as are rigid bikes with skinny tyres.  The more speed you can shed through aerodynamic drag the less braking you have to do.

Obviously a recumbent is even better.  Something like a HPVelotechnik Speedmachine would probably be about right.  No fear of road surfaces, all the braking you could wish for, and the ability to go round corners[1] at speed, which the city bike may be lacking in.

OTOH, I know which I'd rather ride *up* the col...


Quote
If we assume poor road surfaces, then that has to be considered in bike design. Small wheels do not cope as well as large wheels when riding through deep potholes.

Quite.  Small wheels are strong and light, but shit at potholes.  Skinny tyres are a liability on bad surfaces.  If the riding position involves either sitting bolt-upright on a saddle or lying in a recumbent seat, you benefit from rear suspension.  If it involves bearing weight on your wrists, you benefit from front suspension.  But then you're adding weight, and unless handled with tranquillity, suspension can waste energy at the drivetrain.  How important is efficiency?  This stuff is the bread and butter of bike specification, particularly recumbents, where people are less committed to a few standard designs.



[1] I can generally descend faster on my Streetmachine (an overengineered heavy tourer with wide tyres and suspension) than on my Baron (a skinny-tyred low-racer), simply because in the real world resilience to crappy road surfaces is usually more important than coefficient of drag.  The exception is when it's not a straight line; the Streetmachine is designed for stability, and is rubbish at high-speed cornering.
Title: Re: Bike Design
Post by: mrcharly-YHT on March 11, 2018, 05:47:58 pm
Riding down on tri bars on a very low time-trial bike is very very different from riding a sit-up city bike, to take two extremes. I would not like to ride the city bike down a mountain col, give me a race bike for that, please (and I'm talking from a position of safety here, not about riding faster).

If we're playing that game I think I'd prefer the upright city bike, assuming it was a decently made German-style one with proper brakes.
I've had Shimano roller brakes fade and fail from overheating - a good pair of DPs are more reliable in that situation. The city bike won't be great once speed gets up and high speed shimmy when there are sheer drops next to the road would be bloody terrifying. Had that happen first time I took a Gazelle town bike off to the North York Moors. Never again.

It just highlights that it is best to pick the bike designed for the riding style, skill of the rider and conditions. Danny Macaskill can take a road bike offroad and off jumps, but normal mortals would be better off will a full-on sus downhill mtb
Title: Re: Bike Design
Post by: Kim on March 11, 2018, 06:05:16 pm
Riding down on tri bars on a very low time-trial bike is very very different from riding a sit-up city bike, to take two extremes. I would not like to ride the city bike down a mountain col, give me a race bike for that, please (and I'm talking from a position of safety here, not about riding faster).

If we're playing that game I think I'd prefer the upright city bike, assuming it was a decently made German-style one with proper brakes.

I've had Shimano roller brakes fade and fail from overheating - a good pair of DPs are more reliable in that situation.

I was thinking Magura HS11s or something, rather than roller brakes.  Germans fit them because they're cheap and low-maintenance, but they're also surprisingly good at braking.


Quote
The city bike won't be great once speed gets up and high speed shimmy when there are sheer drops next to the road would be bloody terrifying. Had that happen first time I took a Gazelle town bike off to the North York Moors. Never again.

That's a fair point, while I've done short-and-steep I don't think I've ridden one at speeds in excess of 25mph.  On the gripping hand, if you only care about safety then you want to descend at low speed, and the really important thing is brakes that can dissipate all that heat.  At which point the tadpole recumbent trike starts to look like a good idea again (they're mostly contraindicated by high-speed cornering).


Quote
It just highlights that it is best to pick the bike designed for the riding style, skill of the rider and conditions. Danny Macaskill can take a road bike offroad and off jumps, but normal mortals would be better off will a full-on sus downhill mtb

Quite.  The best answer is always n+1.
Title: Re: Bike Design
Post by: Mr Larrington on March 12, 2018, 06:46:22 pm
Chap I know once told me he melted the brake lines on a set of Magura rim brakes, albeit under slightly unusual circumstances, viz. trying to hold a fully-faired recumbent bike down to the speed limit descending from San Bernardino towards the Salton Sea.
Title: Re: Bike Design
Post by: mzjo on March 12, 2018, 08:35:18 pm
I think you've rather missed the point.  I think we can take DF as shorthand for upright position in all its forms. This is about the normative riding position, and what we know about it. You've provided useful scrutiny all the same, since this was in danger of becoming about recumbent vs upright, and that's not the point at all.

If we go back to what was originally posited, is it worthwhile scientifically investigating the benefits and consequences of being upright? And once we know a bit more, what do we do with that information? Is the general confirmation bias too strong?

I think the first thing to investigate is what part bike design actually plays in contributing to accident risk or accident avoidance. I would suspect that it actually plays a very small, even insignificant, part in the cause of accidents. Other factors, such as roaduser education and infrastructure architecture will play a far greater part and rider "clothing" will play a great part in the level of injury resulting from accidents.
This is not to say that mechanical condition doesn't play its part and ease of maintenance aspects of bike design might make a positive contribution to rider safety (so might regular bike MoTs but that's another story)
Title: Re: Bike Design
Post by: Kim on March 12, 2018, 08:38:16 pm
If that paper on single-vehicle bicycle accidents I read a while back was anything to go by, a substantial safety improvement could be made by fitting them with proper racks and panniers.
Title: Re: Bike Design
Post by: mrcharly-YHT on March 13, 2018, 01:13:13 pm
If that paper on single-vehicle bicycle accidents I read a while back was anything to go by, a substantial safety improvement could be made by fitting them with proper racks and panniers.
Handbags and shopping bags tangling in front wheels?
Title: Re: Bike Design
Post by: McWheels on March 13, 2018, 09:40:59 pm
https://www.fastcompany.com/3044557/designed-with-a-roll-cage-this-bicycle-can-survive-a-crash-with-a-semi (https://www.fastcompany.com/3044557/designed-with-a-roll-cage-this-bicycle-can-survive-a-crash-with-a-semi)
Potentially a bit of a Dramatic Event fallacy, but an interesting experiment. Does one belt into that bike instead of hoping to separate? But at least it's the first one I've seen to even model the failure, or 'off', modes for the safety of the rider.


And now for something completely different.
http://birdofpreybicycles.ning.com/ (http://birdofpreybicycles.ning.com/)
Still can't make up my mind if it's genius or somthing else. If you're tipped out the side of it, much harder to keep head and chin off the deck, but that's only what I think.
Title: Re: Bike Design
Post by: ElyDave on March 14, 2018, 08:04:17 am
I can't imagine that Bird of Prey being particularly good on low speed/traffic handling characteristics, or particularly comfortable over audax distances with a bellyfull of beans on toast.  Id does get round the recumbent problem of not being able to see round corners though.
Title: Re: Bike Design
Post by: Cudzoziemiec on March 14, 2018, 09:07:49 am
https://www.fastcompany.com/3044557/designed-with-a-roll-cage-this-bicycle-can-survive-a-crash-with-a-semi (https://www.fastcompany.com/3044557/designed-with-a-roll-cage-this-bicycle-can-survive-a-crash-with-a-semi)
Potentially a bit of a Dramatic Event fallacy, but an interesting experiment. Does one belt into that bike instead of hoping to separate? But at least it's the first one I've seen to even model the failure, or 'off', modes for the safety of the rider.
This reminds me of the DfT's motorcycle leg-protector proposals in the 1980s. The idea was that there should be shock-absorbing panels attached to all motorbikes in front of the rider's legs to lessen the risk of leg injuries in collisions. Manufacturers and riders protested not only on grounds of cost, practicality and aesthetics, but that it paid no attention to where a rider's body might go in a collision or single-vehicle crash. In some circumstances it might be best to stay with the bike, in others it was better to be thrown clear and not have a heavy lump of metal and plastic crush you.
Title: Re: Bike Design
Post by: JennyB on March 14, 2018, 07:23:14 pm
https://www.fastcompany.com/3044557/designed-with-a-roll-cage-this-bicycle-can-survive-a-crash-with-a-semi (https://www.fastcompany.com/3044557/designed-with-a-roll-cage-this-bicycle-can-survive-a-crash-with-a-semi)
Potentially a bit of a Dramatic Event fallacy, but an interesting experiment. Does one belt into that bike instead of hoping to separate? But at least it's the first one I've seen to even model the failure, or 'off', modes for the safety of the rider.
This reminds me of the DfT's motorcycle leg-protector proposals in the 1980s. The idea was that there should be shock-absorbing panels attached to all motorbikes in front of the rider's legs to lessen the risk of leg injuries in collisions. Manufacturers and riders protested not only on grounds of cost, practicality and aesthetics, but that it paid no attention to where a rider's body might go in a collision or single-vehicle crash. In some circumstances it might be best to stay with the bike, in others it was better to be thrown clear and not have a heavy lump of metal and plastic crush you.

I seem to remember a story of a guy who had something like that on his bike - and lost both legs in a head-on crash.
Title: Re: Bike Design
Post by: Kim on March 14, 2018, 08:20:51 pm
If that paper on single-vehicle bicycle accidents I read a while back was anything to go by, a substantial safety improvement could be made by fitting them with proper racks and panniers.
Handbags and shopping bags tangling in front wheels?

One generic category for "forces on the front wheel or handlebars", so entanglement by dangling bags and straps, but also foot-vs-spokes and load-pressed-against-handlebars-by-knee.

The paper concluded that the majority of single-bike crashes were due to infrastructure issues, particularly surface conditions, rather than rider behaviour (including the above) or mechanical failure.  So once again, if we really want to make bicycles safer, it's best to concentrate on the engineering of the environment in which they are used.

Another interesting point it raised was that "loss of control at low speed" was a common factor.  That's something that can to some extent be addressed by engineering the cycles themselves, either by making them more stable and/or by making it easier to accelerate quickly.
Title: Re: Bike Design
Post by: ElyDave on March 14, 2018, 11:19:16 pm
I've had two three SVAs on bikes, both all, arguably my fault

1) RH turn on LH bend with a group. In WInter, in the Fens.  Possible mud/shit/diesel on road, or possible crossed white line, or both.  Either way, both wheels went from under me, cue sliding across the bend to the opposite kerb, bent derailleur hanger and large bruises. On reflection poor choice of tyres for the conditions.
2) Testing recumbents in Lt Thetford with D.Tek, on a Bachetta Giro 26, getting up to some speed through the village.  Similar to above, white line, front wheel washout, sliding along on my right ankle, hip and shoulder.  I still have the scar on my ankle (abraded through two pairs of socks over the ankle bone). 
3) shitty conditions, following a car, over a roundabout, focussing on the RHS sideswipe potential, followed the car across, accelerating.  Stealth ped jumped out onto a zebra crossing 100yds after the r/b, car stopped, I didn't

Of those 1, 2, no real argument, perhaps solveable by a padded road surface or airbag cocoon.

Only number three has any real infrastructure implications.

I'm not counting the almost stationary forget to unclip and fall over incidents
Title: Re: Bike Design
Post by: Kim on March 14, 2018, 11:40:50 pm
Yeah, it's tricky to draw the line between surface problems and rider error.  I've had various falls similar to the above over the years, mostly due to comedy off-roading, which I consider to be entirely my fault.  The others are mostly when innocuous looking conditions have turned out not to be, which could reasonably be described as insufficient paranoia.

OTOH, some features do exacerbate problems.  Those wooden edges on gravel paths spring to mind.  Tactile paving.
 Tramlines and manhole covers that could be designed to be less hazardous to two-wheelers.  Overuse of slippery paint.  Loose gravel surfaces.  Traffic calming that generates potholes.  etc.  etc.
Title: Re: Bike Design
Post by: Cudzoziemiec on March 15, 2018, 09:36:09 am
Tactile paving is often wrongly installed. It's supposed to have the lines perpendicular to movement on the pedestrian side and parallel on the cyclist side, but often it's put in the other way round. This error is probably not important, even for the visually impaired pedestrians it's supposed to help*, as virtually no one sticks to "their" side anyway. More important is using the wrong type of ridges. There are some which are narrow and curved, others which are wide and square edged; the latter are supposed to be used on cycle side (parallel to movement), but often aren't.

*Input from visually impaired pedestrians welcome.
Title: Re: Bike Design
Post by: Karla on March 15, 2018, 09:55:18 am
A bit of a side-step, but here's a fascinating example of original thinking.
Endura put Graeme Obree in a wind tunnel (https://youtu.be/oJ9H0INZ2_s)

It turns out:
His superman position wasn't actually that good - better than others at the time, but nowhere near as good as ...
His original tuck position was massive, way better even than anything we have today. 
He must have got a lot fitter between his two records; for his first (tucked) he could cruise at about 60 watts lower than Boardman et al, but by the time he took it again in superman he was having to put in a world class performance.
Title: Re: Bike Design
Post by: Samuel D on March 15, 2018, 10:34:37 am
He must have got a lot fitter between his two records; for his first (tucked) he could cruise at about 60 watts lower than Boardman et al, but by the time he took it again in superman he was having to put in a world class performance.

I think it’s also that his tuck position incurred a power penalty from the muscular force needed to hold it. It was highly aerodynamic but compromised power at the pedals.

Interesting video.
Title: Re: Bike Design
Post by: Karla on March 15, 2018, 10:44:04 am
Yeah, I think he commented that the superman was better for getting the power out.
Title: Re: Bike Design
Post by: Cudzoziemiec on March 15, 2018, 11:45:34 am
And allowing for the gears and brakes that the current UCI standard has but the crouch on Old Faithful did not, the UCI position comes even closer to crouch: 0.175 v 0.172. Kind of makes you wonder what the point of banning those positions was. Meanwhile, away from the track and TTs, none of them is really practical anyway.