Author Topic: Bike Design  (Read 4956 times)

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Bike Design
« Reply #50 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.
“Procrastination is the thief of time, collar him.” –Charles Dickens

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Bike Design
« Reply #51 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
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.
A cup of tea is the perfect bridge between real life and cake.

JennyB

  • Old enough to know better
Re: Bike Design
« Reply #52 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
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.
Jennifer - walker of hills



Kim

  • Timelord
Re: Bike Design
« Reply #53 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.
Careful, Kim. Your sarcasm's showing...

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Bike Design
« Reply #54 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
“Procrastination is the thief of time, collar him.” –Charles Dickens

Kim

  • Timelord
Re: Bike Design
« Reply #55 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.
Careful, Kim. Your sarcasm's showing...

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Bike Design
« Reply #56 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.
A cup of tea is the perfect bridge between real life and cake.

Karla

  • car(e) free
    • Lost Byway - around the world by bike
Re: Bike Design
« Reply #57 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

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.

Samuel D

Re: Bike Design
« Reply #58 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.

Karla

  • car(e) free
    • Lost Byway - around the world by bike
Re: Bike Design
« Reply #59 on: March 15, 2018, 10:44:04 am »
Yeah, I think he commented that the superman was better for getting the power out.

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Bike Design
« Reply #60 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.
A cup of tea is the perfect bridge between real life and cake.