Author Topic: Audaxing on 650b wheels  (Read 2275 times)

quixoticgeek

  • Mostly Harmless
Re: Audaxing on 650b wheels
« Reply #25 on: August 11, 2019, 12:29:58 pm »

OK, but people buy big tyres to use less pressure, otherwise the extra comfort is negated.
I would say 100-110 PSi for 23 mm tyres and 60 PSI for 32 mm tyres are on average what people use, so if you compare these two data points you can see the rolling resistance is lower for the 23. You need to go abouve 80 PSI in a par of 32 to get  the same CRR, but who use 90 PSI on a pair of 32?

I've got no idea what these Pneumonia severity index units are when it comes to tyres. But I put 5 bar in my 32mm Gp5k tyres...

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

S2L

Re: Audaxing on 650b wheels
« Reply #26 on: August 11, 2019, 12:34:35 pm »

OK, but people buy big tyres to use less pressure, otherwise the extra comfort is negated.
I would say 100-110 PSi for 23 mm tyres and 60 PSI for 32 mm tyres are on average what people use, so if you compare these two data points you can see the rolling resistance is lower for the 23. You need to go abouve 80 PSI in a par of 32 to get  the same CRR, but who use 90 PSI on a pair of 32?

I've got no idea what these Pneumonia severity index units are when it comes to tyres. But I put 5 bar in my 32mm Gp5k tyres...

J

That's 80 PSI... which is a lot, but it is down to weight

quixoticgeek

  • Mostly Harmless
Re: Audaxing on 650b wheels
« Reply #27 on: August 11, 2019, 12:36:56 pm »


That's 80 PSI... which is a lot, but it is down to weight

If you're gonna use funny units, do your conversion properly. 80psi ≠ 5 bar...

I'm ~95kg, and my bike weighs... Too much...

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

S2L

Re: Audaxing on 650b wheels
« Reply #28 on: August 11, 2019, 12:44:46 pm »


That's 80 PSI... which is a lot, but it is down to weight

If you're gonna use funny units, do your conversion properly. 80psi ≠ 5 bar...

I'm ~95kg, and my bike weighs... Too much...

J

Yeah 73 PSI, still quite high, but I would say it's right for your weight

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Audaxing on 650b wheels
« Reply #29 on: August 11, 2019, 01:09:43 pm »
The chart comparing different widths at "equal comfort," which they define as equal tyre squish in mm, finds no difference in rolling resistance between widths.
A cup of tea is the perfect bridge between real life and cake.

S2L

Re: Audaxing on 650b wheels
« Reply #30 on: August 11, 2019, 01:52:45 pm »
The chart comparing different widths at "equal comfort," which they define as equal tyre squish in mm, finds no difference in rolling resistance between widths.

it begs the question why don't we all ride 32 mm... I've tried many, from touring ones (Vittoria Randonneur and Voyager, Panaracer Pasela) to road ones (Hutch Sector tubeless and Conti Gatorskins) to fast dry-CX ones (Vittoria XN)... they were all significantly inferior to a pair of Rubino PRO or Durano in 25 mm and very inferior to premium race tyres like Vittoria Corsa

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Audaxing on 650b wheels
« Reply #31 on: August 11, 2019, 02:00:19 pm »
Probably for the same sort of reasons that some of us ride 6kg carbon goodness and some a Hercules tradesman's cycle with double crossbar and reinforced forks (and most of us ride neither of these while some ride both).
A cup of tea is the perfect bridge between real life and cake.

S2L

Re: Audaxing on 650b wheels
« Reply #32 on: August 11, 2019, 02:18:03 pm »
Like for like, Hutch Sector 28 were a hell of a lot better than Hutch Sector 32... neither was a stellar tyre, but the 32 felt really slow and didn't corner as well.
The randonneur were not terrible, decent handling and were pretty much punctureproof, but on a very hilly route they would wear me down a lot more than a pair of 25 mm road tyres... after all they were a pound of tyre each

Re: Audaxing on 650b wheels
« Reply #33 on: August 11, 2019, 05:09:22 pm »

Yeah, 650b carbon wheelsets exist:

https://www.huntbikewheels.com/products/650b-adventurecarbon-disc

In theory, shouldn't a 622 x 28 be the same outer diameter as a 584 x 47?

Thus negating the gear size difference ?

J

I wish I hadn't seen that link!!  But I am a bit dubious about 28mm tyres on a 24mm wide rim (unless they are talking about external width and the interior is a lot narrower - or tubeless tyres don't obey the same rules as tubed).

re diameters. This link may help  http://www.bikecalc.com/wheel_size_math  even if as they say the method of calculation used may give different results between sources, for comparison purposes figures within the same table should be adequate. I can't remember how my roll-out measures for setting the counter compare but I think they were pretty close.


That's 80 PSI... which is a lot, but it is down to weight

If you're gonna use funny units, do your conversion properly. 80psi ≠ 5 bar...

I'm ~95kg, and my bike weighs... Too much...

J

Surely we would be better using some multiple of Pascal (KPa seems to ring a bell somewhere, or is it kPa? I can't remember!). Having come from an industry where a bar was 1kg/cm2 (which is not an official measure of pressure) and kilo was a generic term for all measures!
I pump my tyres so that my thumb doesn't sink in too far when I press and my weight is what it is since the scales gives obviously false figures.

Edit: I can't help thinking that this is getting away from the subject matter of the Audax board and onto the territory of the Knowledge one. Haven't we had some of these arguments before somewhere?

zigzag

  • unfuckwithable
Re: Audaxing on 650b wheels
« Reply #34 on: August 11, 2019, 06:04:03 pm »
wider tyres will be slower, but will give more comfort if not pumped up too hard. you can ride audaxes on many different sized wheels and tyres, just choose (or try and see) what's important to you - different people prefer different levels of speed/comfort. my sweet spot for the paved roads is 26-27mm(actual), which is what i ride.

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Audaxing on 650b wheels
« Reply #35 on: August 11, 2019, 06:15:37 pm »
A quick look around the stable reveals Continentals marked in psi and bar, Vittoria marked in bar and psi, Panaracer in kPa, bar and psi, and Specialized in psi and bar.
A cup of tea is the perfect bridge between real life and cake.

FifeingEejit

  • Not Small
Re: Audaxing on 650b wheels
« Reply #36 on: August 11, 2019, 11:09:52 pm »
Surely we would be better using some multiple of Pascal (KPa seems to ring a bell somewhere, or is it kPa? I can't remember!). Having come from an industry where a bar was 1kg/cm2 (which is not an official measure of pressure) and kilo was a generic term for all measures!
I pump my tyres so that my thumb doesn't sink in too far when I press and my weight is what it is since the scales gives obviously false figures.

Edit: I can't help thinking that this is getting away from the subject matter of the Audax board and onto the territory of the Knowledge one. Haven't we had some of these arguments before somewhere?

I had to double check, but it turns out I do remember Higher Physics and Engineering correctly:

"A bar (symbol: bar) is a metric unit of pressure that is defined as exactly 100,000 pascals (symbol: Pa). "
I did have to check:
"Reduced to base units in SI, one pascal is one kilogram per meter per second squared"

The pascal is a derived unit, and the bar further derived which was designed for weather forecasting.

Though I do find 40psi easier to remember that 7.75 Bar would 276 Kpa be easier to use?
It's certainly much easier than using the SI unit (N/m^2) which is 275789.79302

Re: Audaxing on 650b wheels
« Reply #37 on: August 12, 2019, 02:37:36 pm »
Rode a DIY with Iroromono today, he was on his  "650b"-42mm47mm shod Kinesis while I was on the Equilibrium with 622-28mm Conti 4 Seasons.
His tyres worked out slightly smaller.

Other than his gearing being odd shaped and lacking a mech can't say anything was noticeably different to normal; he goes up hills faster even when hanging back for me, and I go faster down hill without pedalling.  We did do a bit of an old railway where his tyres seemed to be of significant advantage although that didn't stop me riding at the same pace.

 I've got it setup with 47mm WTB Horizons. I can't say that it feels slower than  a 700c wheel with 30mm tyres on road. Perhaps it is a little slower descending, however was  made up for by the benefit of floating over the rough Scottish roads at 40psi.

The oval chainring is strange and with the slightly smaller wheels the 42x10 biggest gear was probably a little light for 1-2% declines where you might like to pedal.

wilkyboy

  • "nick" by any other name
    • 16-inch wheels
Re: Audaxing on 650b wheels
« Reply #38 on: August 13, 2019, 01:08:20 pm »
Smaller wheels are more robust than bigger wheels... Brompton 16 inch wheels are pretty much indestructible... it's all down to trigonometry and what are called "bracing angles".

 :thumbsup:

I started a 200km audax knowing that my Brompton rear was missing four drive-side spokes, two of them adjacent to each other.  The wheel stayed almost-true and didn't give me a moment's concern all the way around.

16-inch wheels really are bullet-proof, unlike 700C.
RRTY #7 done.  Need something else to do ... ah, welcome #8 8)

FifeingEejit

  • Not Small
Re: Audaxing on 650b wheels
« Reply #39 on: August 13, 2019, 01:10:22 pm »
Smaller wheels are more robust than bigger wheels... Brompton 16 inch wheels are pretty much indestructible... it's all down to trigonometry and what are called "bracing angles".

 :thumbsup:

I started a 200km audax knowing that my Brompton rear was missing four drive-side spokes, two of them adjacent to each other.  The wheel stayed almost-true and didn't give me a moment's concern all the way around.

16-inch wheels really are bullet-proof, unlike 700C.

Aye but you lose the rollover for those pot holes you can't avoid forcing you to learn to bunny hop.
(rehash of old MTB 26 Vs 29 arguments.)

wilkyboy

  • "nick" by any other name
    • 16-inch wheels
Re: Audaxing on 650b wheels
« Reply #40 on: August 13, 2019, 01:14:29 pm »
In the MTB world there is a lot of debate between 29” and 26” wheels and the consensus seemed to be on balance there’s no overall difference.

I have a mountain bike with 26-inch wheels, and one with 650b, and the bigger wheels are noticeably better at rolling over rough stuff.
RRTY #7 done.  Need something else to do ... ah, welcome #8 8)

S2L

Re: Audaxing on 650b wheels
« Reply #41 on: August 13, 2019, 07:36:51 pm »
Smaller wheels are more robust than bigger wheels... Brompton 16 inch wheels are pretty much indestructible... it's all down to trigonometry and what are called "bracing angles".

 :thumbsup:

I started a 200km audax knowing that my Brompton rear was missing four drive-side spokes, two of them adjacent to each other.  The wheel stayed almost-true and didn't give me a moment's concern all the way around.

16-inch wheels really are bullet-proof, unlike 700C.

They are... they are also symmetric, as opposed to dished, which makes them even stronger.
Brompton build their wheel with 28 spokes, but at that size I don't think they need more than 16, whereas 700c wheels with fewer than 28 spokes are a bit of a grey area when it comes to reliability

Re: Audaxing on 650b wheels
« Reply #42 on: September 01, 2019, 12:39:25 pm »
So I have taken the plunge and bought an On-One Space Chicken with 1 x 11 SRAM Rival group set and 650b wheels.

Took it on holiday to Dorset last week and rode the standard 98km route of the Jurassic Beast sportive.

https://ridewithgps.com/routes/22056161

Pretty pleased with it so far although the SRAM gear shifting takes a bit of getting used to after riding Shimano for many years.

The hydro brakes have amazing stopping power and the stock 42mm tyres soaked up lots of vibration. I did not seem noticeably slower than riding my normal road bike. Will probably swap out the saddle and fit some mudguards and then try a 200km audax on it.

BTW Dorset has fabulous scenery and riding - any recommendations for calendar events down there?

bludger

  • Randonneur and bargain hunter
Re: Audaxing on 650b wheels
« Reply #43 on: September 01, 2019, 05:40:16 pm »
Great to hear you're off to a fun start with the space chicken - a friend is on the tipping edge of buying one himself though I think it'll be 700c. Don't forget it can accommodate dropper post routing! Though admittedly this might be of limited utility with a saddlebag etc on ;D
YACF touring/audax bargain basement:
https://bit.ly/2Xg8pRD


JonB

  • Granny Ring ... Yes Please!
Re: Audaxing on 650b wheels
« Reply #44 on: September 01, 2019, 10:22:27 pm »
BTW Dorset has fabulous scenery and riding - any recommendations for calendar events down there?

There's the Wessex Series, that'll keep you busy :demon: Details here https://www.dorsetaudax.org.uk/audax-wessex-series/ and here http://www.wessexsr.org.uk both of these links contain details and dates for the 2019 rides, not sure if next year's are up yet but a bit of searching on the AUK calendar will reveal them if they're there. You'll have the added bonus of the Crackpot 1000 next year.