Author Topic: Audaxing on 650b wheels  (Read 2274 times)

Audaxing on 650b wheels
« on: August 10, 2019, 04:11:45 pm »
Hi,
Hope a gear discussion is ok in this forum. I have noticed a few bikes with 650b wheels on recent audaxes and was wondering if anyone on here uses them?

If yes can you answer the following questions.

Are you faster/slower/no difference on the smaller wheels?
Which tyres do you use?
Do you run with tubes or tubeless?
How is the puncture resistance?
What mudguards are you using? (if you do).

I am very tempted to try the smaller wheels as quite a few of the audaxes I have ridden recently have had non tarmac sections (which admittedly I got through ok on 700x25 tyres) and I quite fancy something that would cope with pot-holed roads more easily.

PaulF

  • "World's Scariest Barman"
  • It's only impossible if you stop to think about it
Re: Audaxing on 650b wheels
« Reply #1 on: August 10, 2019, 04:22:39 pm »
In theory bigger wheels will roll better over obstacles (like potholes), accelerate slower (but hold momentum better) and be slower turning than a smaller wheel. Whether you’d notice any real world difference is down to you. 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.

Also if you just put 650b wheels on a frame designed for 700c it will change the geometry and handling. Whether it’s an improvement will be down to your preferences.

Can5 see either wheel size having an advantage in puncture resistance.

Zed43

  • prefers UK hills over Dutch mountains
Re: Audaxing on 650b wheels
« Reply #2 on: August 10, 2019, 05:03:04 pm »
Hope a gear discussion is ok in this forum. I have noticed a few bikes with 650b wheels on recent audaxes and was wondering if anyone on here uses them?
I have two bespoke steel bicycles that were designed for 584 aka 650b rims and wide(r) tyres.

One bike was intended as a touring bike (tent, cooking gear, the works) with a Rohloff hub. It has 700c aluminium mudguards made by Velo Orange that leave a lot of room with 42mm tyres, but also allow 48mm tyres. When the 42mm Grand Bois Hetres have worn down I'll use the 48mm Compass Switchback Hill exclusively; I used those last year on the This Is Not A Tour (the 300km gravel version) and while touring Wales and the South-West and they are just wonderful. I have also done several other brevets with this bike, including the Byan Chapman.

The other bike is a randonneur pur sang; derailleur geared with 6% steps between gears, 38mm Compass Loup Loup Pass tyres and fancy carbon mudguards. Have been riding this bike for 6 months now, including The Border Raid and will be riding it next week for PBP.

Choice of tyres will make more of a difference than wheel size (at least when comparing 700c with 650b) for speed. With a cruising speed of ~26kph the "aerodynamic penalty" of the wider tyres is (over?)compensated by the reduced rolling resistance. Punctures are a rare occurrence for me; possibly because of the combination of a light rider, wide tyres at low pressure. But the 650b tyres are not different in this respect than the 28mm GP4000 that I have used before. At the moment I don't have a combination of rims and tyres that I can use tubeless; I'm using Schwalbe SV12 tubes with XXLight SV14a spares in my bag (they pack noticeably smaller)

I do notice I descend faster (esp. on bad roads) than many other people. Either because I'm just stupid or because those big tyres give a lot of confidence.

If your bike uses disc brakes you only need to worry about clearance in the frame and fork, otherwise you may also need new brakes with longer reach.

S2L

Re: Audaxing on 650b wheels
« Reply #3 on: August 10, 2019, 05:13:11 pm »

Choice of tyres will make more of a difference than wheel size (at least when comparing 700c with 650b) for speed. With a cruising speed of ~26kph the "aerodynamic penalty" of the wider tyres is (over?)compensated by the reduced rolling resistance.

Every graph I have ever seen, as well as anecdotal evidence, point in the direction of lower rolling resistance for smaller width... at least on relatively smooth surface like tarmac.

IMO people tend to overplay "rough stuff" and are prepared to compromise on 95% of a route, so that they can have the ideal tyres for the remaining 5%... common sense would suggest the opposite is a better approach

Years ago I was cycling with 32 mm tyres because I thought they were the best compromise... reality is that they were slow and heavy

bludger

  • Randonneur and bargain hunter
Re: Audaxing on 650b wheels
« Reply #4 on: August 10, 2019, 06:03:41 pm »
I am 650b curious in great part because it seems they have excellent mudguard clearance. But also they are (am I right) inherently more robust in terms of bumps and weight bearing than 700c. Since I'm already a bit pushing my 120kg limit on my Mavic Allroads if I were to really go weapons grade loaded touring this is of particular interest to me.

Would possibly have to use shorter cranks to prevent pedal strike though.
YACF touring/audax bargain basement:
https://bit.ly/2Xg8pRD


S2L

Re: Audaxing on 650b wheels
« Reply #5 on: August 10, 2019, 06:08:17 pm »
I am 650b curious in great part because it seems they have excellent mudguard clearance. But also they are (am I right) inherently more robust in terms of bumps and weight bearing than 700c. Since I'm already a bit pushing my 120kg limit on my Mavic Allroads if I were to really go weapons grade loaded touring this is of particular interest to me.

Would possibly have to use shorter cranks to prevent pedal strike though.

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".

Mudguard clearance depends on tyre size, if you use 40 mm + tyres, you are probably overall at a similar size to a 23 on 700 c rims, although they will be wider, hence need wider guards.

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Audaxing on 650b wheels
« Reply #6 on: August 10, 2019, 07:07:06 pm »
IMO people tend to overplay "rough stuff" and are prepared to compromise on 95% of a route, so that they can have the ideal tyres for the remaining 5%... common sense would suggest the opposite is a better approach

Years ago I was cycling with 32 mm tyres because I thought they were the best compromise... reality is that they were slow and heavy
I get your point; but the reality in most countries is that the "95% tarmac" bit can be a pretty shitty surface, which either;
- the rider is irritated by, or
- the rider is fatigued by, especially on very long events.

So adding some comfort (at cost of extra RR) can be attractive. YMMV, as some say!
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: Audaxing on 650b wheels
« Reply #7 on: August 10, 2019, 09:26:14 pm »
I may be mistaken but don't 650b (or any smaller wheel) give you lower gear ratios so climbing is easier for the same front and rear cog? That's the thought that keeps me going when I'm slogging up a hill on my heavy 650b wheeled Surly

Re: Audaxing on 650b wheels
« Reply #8 on: August 10, 2019, 09:38:43 pm »

Choice of tyres will make more of a difference than wheel size (at least when comparing 700c with 650b) for speed. With a cruising speed of ~26kph the "aerodynamic penalty" of the wider tyres is (over?)compensated by the reduced rolling resistance.

Every graph I have ever seen, as well as anecdotal evidence, point in the direction of lower rolling resistance for smaller width... at least on relatively smooth surface like tarmac.
Well have a look at the graphs in this comparative test, @S2L.
Width v rolling resistance, not taking into account body shaking losses
https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison

Re: Audaxing on 650b wheels
« Reply #9 on: August 10, 2019, 09:46:32 pm »
I have yet to get back to audaxing and my 650b experience is from since my op (and I was only 200 standard before that) so with that rider on my observations

1 Using a 700c frame (that will take up to 28 tyres under the guards) the change in diameter has little noticeable effect on handling. The wider tyres do have a much bigger effect on bike behaviour. On the Peugeot that I converted the change to the handling made very little difference to the riding experience (28x622 v 32x584). On my current mtb conversion the 32x584 are quicker than 26x1.5 (easier rolling) but the handling difference is unnoticeable.

2 On smooth surfaces the 23x622 are much quicker. Once the surface gets more granular (top dressing broken up by frost etc) 28's are better than 23's but 32x584 are in a different league. 26x1.5 is not in my experience that much better than 32x584. For me 32mm seems to be a good compromise for comfort - my 650b bike is the first choice for route testing for this reason alone.

3 If you want to use 650B with rim brakes (swopping between 622 and 584 and using deep brakes) it is possible but the choice of rims is limited and can be pricy (this is especially the case in France  ???) and heavy (ditto). I have sourced 32h rims from SJS in UK because there is absolutely nothing available for the weight and price in France. If you are using much wider rims and tyres and disc brakes the choice is much easier. (Anecdotally my current conversion is using discs but the rims are 19mm wide and suited to rim brakes; I stopped using the Peugeot because I needed the rims for the tandem!).

4 There are (as in all things) good tyres and less good tyres. Even if there is an advantage in going wide a wide Compass tyre is still going to be streets ahead of a supermarket IRC demi-ballon (which is about the same size). My 32mm Hutchinson tyres are better than the IRC (and probably more comfortable). I would like to have the money to try the Compass tyres in a big section but life ain't like that. If you want to swap between big section 650b and 700c then it really needs a frame suited to the job and almost certainly disc brakes (if only for the availability of rims). There are gravel frames that would fit the bill. Whether they would be suited to the rider's use is another matter, of course.

My tyres are 32x584 Hutchinson Confrérie de 650B (which are light, quick, comfortable and relatively cheap, especially for members of the Confrérie; slick treads which I personally would not want in mud) and Schwalbe HS165 reinforced (no longer made I think) which are like a Michelin World Tour that rolls much better than the Michelin and lasts much longer. The Hutchinsons are kevlar beaded, the Schwalbe rigid

The next step for me will be to fit one of my old racing frames with deep brakes and 650b Hutchinsons and get back to a bit of long distance - 2020 perhaps?

Re: Audaxing on 650b wheels
« Reply #10 on: August 10, 2019, 10:13:30 pm »
I may be mistaken but don't 650b (or any smaller wheel) give you lower gear ratios so climbing is easier for the same front and rear cog? That's the thought that keeps me going when I'm slogging up a hill on my heavy 650b wheeled Surly

Yes – a smaller wheel means lower gearing.

Assuming a tyre of the same profile, the difference in gearing is 622/584 - 1, or about 6.5%.  Roughly equivalent to swapping your 34T chainring for a 32T.

In reality, though, you're likely to have a larger tyre on a 650b wheel, which reduces the effect a bit.

Re: Audaxing on 650b wheels
« Reply #11 on: August 10, 2019, 10:14:52 pm »
IMO people tend to overplay "rough stuff" and are prepared to compromise on 95% of a route, so that they can have the ideal tyres for the remaining 5%... common sense would suggest the opposite is a better approach

Years ago I was cycling with 32 mm tyres because I thought they were the best compromise... reality is that they were slow and heavy
I get your point; but the reality in most countries is that the "95% tarmac" bit can be a pretty shitty surface, which either;
- the rider is irritated by, or
- the rider is fatigued by, especially on very long events.

So adding some comfort (at cost of extra RR) can be attractive. YMMV, as some say!

You should visit Bavaria :smug:

bludger

  • Randonneur and bargain hunter
Re: Audaxing on 650b wheels
« Reply #12 on: August 10, 2019, 10:28:22 pm »
being at a loose end, I decided to upload my GPX from my Roubaix sportive (120 km of road, and 52 km of pavé) into komoot to see how it viewed the surfaces I rode on, wondering if komoot etc may potentially badly mislead route planners in terms of what they're getting in to. It scored pretty much the whole thing as 'road', though I was impressed that it detected that the surfaces differed and picked up 'cobblestones' as a distinct surface type. The other two surface types were 'paved' and 'asphalt'... On the whole it summarised the route as "Expert road ride. Very good fitness required. Some portions of the Tour may be unpaved and difficult to ride."
YACF touring/audax bargain basement:
https://bit.ly/2Xg8pRD


vorsprung

  • Opposites Attract
    • Audaxing
Re: Audaxing on 650b wheels
« Reply #13 on: August 10, 2019, 10:37:10 pm »
the shadow of Jan Heine is long
Audaxing Blog follow @vorsprungbike on

Re: Audaxing on 650b wheels
« Reply #14 on: August 10, 2019, 11:31:30 pm »
Thanks for the responses all.

Full disclosure - I am considering an N+1 gravel bike and wondering whether it can do double duty as an audax bike.

The model I am looking at comes with 650b 42mm tyres which I guess would not be too much smaller than the 700x25c which are the largest which I can fit on my current bike when using guards.

I have not rode at TINAT but this style of bike sounds ideal for that style of riding (although some chaps I was chatting to recently said a proper hardtail MTB would have been better for the 200km event they did this year).

Re: Audaxing on 650b wheels
« Reply #15 on: August 11, 2019, 12:07:51 am »
Years ago I was cycling with 32 mm tyres because I thought they were the best compromise... reality is that they were slow and heavy
You may find that there's a better choice of 32's now than there was years ago, whereas the choice in narrower tyres was already pretty decent.

FifeingEejit

  • Not Small
Re: Audaxing on 650b wheels
« Reply #16 on: August 11, 2019, 12:23:29 am »
Rode a DIY with Iroromono today, he was on his  "650b"-42mm 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.

mattc

  • n.b. have grown beard since photo taken
    • Didcot Audaxes
Re: Audaxing on 650b wheels
« Reply #17 on: August 11, 2019, 08:19:22 am »
IMO people tend to overplay "rough stuff" and are prepared to compromise on 95% of a route, so that they can have the ideal tyres for the remaining 5%... common sense would suggest the opposite is a better approach

Years ago I was cycling with 32 mm tyres because I thought they were the best compromise... reality is that they were slow and heavy
I get your point; but the reality in most countries is that the "95% tarmac" bit can be a pretty shitty surface, which either;
- the rider is irritated by, or
- the rider is fatigued by, especially on very long events.

So adding some comfort (at cost of extra RR) can be attractive. YMMV, as some say!

You should visit Bavaria :smug:

 :P
Has never ridden RAAM
---------
No.11  Because of the great host of those who dislike the least appearance of "swank " when they travel the roads and lanes. - From Kuklos' 39 Articles

Re: Audaxing on 650b wheels
« Reply #18 on: August 11, 2019, 09:06:22 am »
I have not rode at TINAT but this style of bike sounds ideal for that style of riding (although some chaps I was chatting to recently said a proper hardtail MTB would have been better for the 200km event they did this year).

The off-road sections on the most of the TINAT courses are pretty short and not muddy. The climbing (most of it on road) is immense. Low gear ratios for steep climbs, fast rolling on tarmac and saving weight* are more important. TCR - which had long gravel sections - was won on a carbon road bike with 28mm slick road racing tyres.

(* remembering that the bulk of the weight on a bike isn't the bike)

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Audaxing on 650b wheels
« Reply #19 on: August 11, 2019, 11:10:27 am »
I have not rode at TINAT but this style of bike sounds ideal for that style of riding (although some chaps I was chatting to recently said a proper hardtail MTB would have been better for the 200km event they did this year).

The off-road sections on the most of the TINAT courses are pretty short and not muddy. The climbing (most of it on road) is immense. Low gear ratios for steep climbs, fast rolling on tarmac and saving weight* are more important. TCR - which had long gravel sections - was won on a carbon road bike with 28mm slick road racing tyres.

(* remembering that the bulk of the weight on a bike isn't the bike)
And neither is the bulk of winning TCR.
A cup of tea is the perfect bridge between real life and cake.

Re: Audaxing on 650b wheels
« Reply #20 on: August 11, 2019, 11:20:00 am »
I have not rode at TINAT but this style of bike sounds ideal for that style of riding (although some chaps I was chatting to recently said a proper hardtail MTB would have been better for the 200km event they did this year).

The off-road sections on the most of the TINAT courses are pretty short and not muddy. The climbing (most of it on road) is immense. Low gear ratios for steep climbs, fast rolling on tarmac and saving weight* are more important. TCR - which had long gravel sections - was won on a carbon road bike with 28mm slick road racing tyres.

(* remembering that the bulk of the weight on a bike isn't the bike)

I don't think that weight should be a consideration in the argument. Most of the narrow rim brake compatible rims that I have looked at are 500-600 grams, mainly at the heavy end of the scale. The tyres seem to be comparable with 700c equivalents - but don't go looking for 200 gram tyres, I don't think there are any  :hand: I will admit not knowing anything about weights of high end carbon rims or if they exist in 650b and disc rims should be lighter, except that there aren't many that will take my width of tyre and as the width increases the weight usually does (following the rule weight, price, width you can have any two but not all three).

I used to be amused by the fact that Berthoud's 650b tourers always weighed more than their 700c equivalents, usually by about 1kg (manufacturer's figures).

Edit: The SJS rims that I use are sub-500gram - 450gm IIRC, which is one of the things I like about them.

quixoticgeek

  • Mostly Harmless
Re: Audaxing on 650b wheels
« Reply #21 on: August 11, 2019, 11:27:17 am »

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

Re: Audaxing on 650b wheels
« Reply #22 on: August 11, 2019, 11:28:33 am »
I have not rode at TINAT but this style of bike sounds ideal for that style of riding (although some chaps I was chatting to recently said a proper hardtail MTB would have been better for the 200km event they did this year).

The off-road sections on the most of the TINAT courses are pretty short and not muddy. The climbing (most of it on road) is immense. Low gear ratios for steep climbs, fast rolling on tarmac and saving weight* are more important. TCR - which had long gravel sections - was won on a carbon road bike with 28mm slick road racing tyres.

(* remembering that the bulk of the weight on a bike isn't the bike)

I think that with the right tyre section slick tyres are probably at no disadvantage on gravel if it's dry. On mud it may be a different matter (except that slicks shouldn't pick up as much mud. What you lose on traction you gain on incidental weight and inertia)

quixoticgeek

  • Mostly Harmless
Re: Audaxing on 650b wheels
« Reply #23 on: August 11, 2019, 11:34:32 am »

I think that with the right tyre section slick tyres are probably at no disadvantage on gravel if it's dry. On mud it may be a different matter (except that slicks shouldn't pick up as much mud. What you lose on traction you gain on incidental weight and inertia)

A lot also comes down to experience and bike handling skills. On my way home from the TCR, I was overtaken by 2 riders on road bikes with 25ish mm tyres. There was a diversion on the cycle way and it went onto a gravel section, with large stones maybe 30-50mm in diameter. The pair that had over taken me were ~150m ahead of me by the time they entered the gravel section. I over took them with about 5-10m to go. Having the confidence, and experience of such terrain (thanks sustrans), can really help.

I was on my fully loaded bike, one of the pair had a saddle bag (size smaller than mine), one had a backpack (maybe 15-20l).

It was dry, so the argument about in the dry vs wet may hold up here.

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

S2L

Re: Audaxing on 650b wheels
« Reply #24 on: August 11, 2019, 12:15:19 pm »

Choice of tyres will make more of a difference than wheel size (at least when comparing 700c with 650b) for speed. With a cruising speed of ~26kph the "aerodynamic penalty" of the wider tyres is (over?)compensated by the reduced rolling resistance.

Every graph I have ever seen, as well as anecdotal evidence, point in the direction of lower rolling resistance for smaller width... at least on relatively smooth surface like tarmac.
Well have a look at the graphs in this comparative test, @S2L.
Width v rolling resistance, not taking into account body shaking losses
https://www.bicyclerollingresistance.com/specials/grand-prix-5000-comparison

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?