oneraindog

im curious about 650b on a randonneuring bike. why dont we see more? what is the advantage to 700c other than accessibility?
650b comes with so much comfort why NOT ride that type of bike?

supcom

650B is a new old standard and has limited support in the US. Try to find anything 650B in the typical LBS and you'll go home empty handed.

650b also has a long way to go in convincing people that fat tires can keep up with skinny ones. I ride 700cx30 Grand Bois tires, so I know the advantages of smooth ride with little performance impact.

late

The Grand Bois was imported for a year as a 650b before the popularity of it encouraged the Vintage Bike guys to bring over the 700c version. Not much difference there....

But I wonder if that tire has enough toughness for a randonneuring event.

I don't see a problem in the size. But I wonder how well an off the shelf bike will
compete against a bike purpose built for randonneuring. I think the lightest 650b rim is the Synergy at 490 gr. I think if we see a Open Pro 650b rim...or perhaps one of the fancy schmancy wheels makers come out with some performance oriented gear for 650b... then I wouldn't hesitate.

LWaB

You can't borrow a spare tyre from somebody else...

late

If somebody else can bring a spare, is there some reason you could not?

I have got to say that 650b tires are pillows. At the low pressure they get run at;
it's not going to be much of an issue.

Buglady

OK, Noob question here - how different is 650b from 26"?

spokenword

650b is slightly larger than a 26" MTB wheel. 700C road wheel are 622mm in diameter. 26" MTB wheels are 559. The 650B is 584mm. So basically, you get the speed and handling characteristics of a 700c wheel but with the sturdiness of a mountain bike tire. One can adapt a conventional geometry road bike to 650B, and by doing so, allow yourself to mount wider tires and fenders because you now suddenly have more clearance between your wheel and brakes. So you can basically turn a conventional road/racing bike into a comfortable, all-weather riding machine without much sacrifice in speed or handling, so long as you're willing to live with constrained tire choices (like throwing down $100 for a pair of Gran Bois Cypres tires)

as always, Sheldon Brown has a pretty good primer on his site, if you're interested.

with that said, if you've got a road bike built around 26" wheels, I don't think you can convert that to 650B, so you can't 'upgrade' to get the slight speed improvements that come with a larger wheel.

late

Here's a more subjective opinion. Mtn bike tires tend towards the rugged side.
650b tires tend to be more like pillows. I am exagerating to make a point, the 650b
is an old French style of bike. You have a choice of different tires, but I think the whole point is to get a large tire which you can run at low pressure. My wife's bike's tires have about 50 psi. That's it. Like pillows...

LWaB

The fact that I don't carry spare tyres for 600s or shorter but some do. OTOH I carry a few more spare bolts and tools than most. I figure it'll even out when I need to borrow a tyre.

late

I meant if you had a 650b bike yourself. If you want to know the truth, I haven't carried a thing
so far this year, no pump, no patch, not a thing. My new tires are great, my wife never gets a flat. Guess I should be a little more paranoid

spokenword

so, then as a follow up question -- why not run 37mm or 42mm tires on a 700c wheel?

I realize that this would be impossible with most caliper brakes, but what about cantilever brakes on a touring or cyclocross book. That will give you plenty of clearance for fenders and a wide tire, but still put you in a wheel size that gives you a lot of tire options. What is it about the 650b size that makes sturdy, low-pressure more viable than 700c?

oneraindog

from a weight stand point there would be many reasons not to want to put tires that large on a 700c tire. though i must admit i dont know how the weight comparison would break down between a 37+ tire on a 650b wheel compared to the same size tire on a 700c wheel but logically it would seem like it would be heavier(?)

i have also been given the impression by those with wheel building experience in both sizes that just by a function of diameter the 650b wheel is sturdier. the tighter the circumference of wheel the more resistant to denting or disfigurement it will be. although as it stands good 700c wheels are built to be very sturdy and probably just as sturdy as the limited 650b makes but if the 650b continues to gain popularity the engineering may begin to incorporate lighter, stronger structure. granting this hypothetical situation, what will 700c have over 650b?

Six jours

Toe overlap.

I'm currently running the 700c Grand Bois Cypres with fenders, and I have about two inches of overlap. This is not the nightmare that some people believe it to be, but it is mildly irritating. I would very much like to ride a 40 MM tire without overlap, and I think the 650b is the best way to get from here to there.

A few other posters, BTW, have alluded to a very important thing, IMO: the available styles of 650b tire are almost unique. The 700c Grand Bois is a wonderful tire, but it is the widest tire of its class available, as far as I know. All wider 700c tires that I'm aware of are much heavier, with much less supple casings and much thicker treads. This makes all the difference in the world, as far as ride quality goes. I have a pair of 700x28 tires that are absolute pigs compared to the Grand Bois, owing entirely to the heavy and inflexible casing and the thick tread. A tire of the same construction as the Grand Bois, but 10 mm wider, would be my idea of perfection for bad surfaces and fire roads -- except that in 700c, your front center would have to be Grand Canyon-esque if toe overlap is to be avoided.

Regardless, as far as I am aware, a light 40mm tire is only available in the 650b. No 700c tire of lightweight construction is available in wider than 30mm, and no 26" tire of equally light construction is available at all, that I have seen.

So the short version is that, IMO, it's not the size of the wheel but the availability of tires. If someone wanted to make a 40mm 26" tire of light construction, it would likely be essentially identical to a good 650b set-up.

<edit> But if you do not care for a lightweight tire and do not mind the "stuck to the ground" sensation of a more heavily constructed tire, there is probably no reason for you to put up with the headaches of the 650b. Heavily constructed 26" tires are widely available.

Bekologist

bring back the 635, dangnabbit. and the 590.

but 650B? industry buzz suggests 27.5 is the phoenix rising.

I predict 3 years for 27.5 to mature, and equally as many to decline again.

Six jours

LOL. It does all get a bit silly, doesn't it?

I'm not one to argue that a few millimeters one way or the other make some magical difference. Essentially, I want the largest lightweight "pillow" tire available that doesn't require serious frame geometry compromises to avoid toe overlap. 650b looks to be that size.

spokenword

mmm ... good point. I had the same problem with running the 30mm Cypres on my brevet bike, and eventually when I swapped them out for 28mm Panaracer Paselas, I found that I was able to take my fenders in enough to remove concerns about toe overlap. I noticed on the VBQ site that there are a set of 28mm Cypres tires available, and that has me tempted. My first experience with the Cypres were colored by experiencing a higher than average rate of flats, but I've seen enough people talk up the wonders of their tires, that I'm willing to chalk it up to the folly of getting one of the first sets of the 700C tires which may have had some production kinks Still my experience with riding a Cypres in the New England winter would lead me away from using them on fire roads or poor surfaces.

Hocam

We've all seen the 29er trend in mountain biking, but what about the 30 incher? 27" wheels with knobby tires! 8 more mm. of diameter!


The problem I have with wider tires is they generally do feel sluggish compared to 25's or 23's. My distance bike is also my fast bike, and with the knee problems I've been having lately I tend to be doing 2-3 hour fast or hilly rides instead of 8 hour events where the extra comfort would be more welcome.

As for toe overlap, the Bilenky in my sig hardly has any which I assume is from generous amounts of fork rake and a shallow head tube angle but it still handles great. Finally, it's built for fender clearance and I do install them on rainy days.

The only circumstance I could see myself trying 650B is if I found a nice italian or japanese race bike for cheap and wanted to make it more comfortable for distance. However, I already have a fantastic distance bike, so that's a little unlikely.

LWaB

It would be a lot easier to introduce nice 26" tyres than popularise 650Bs but fashion and product differentiation wins again...

supcom

I use my Grand Bois tires randonneuring all the time with no problems.

Bacciagalupe

Why do I get the feeling that if 650b was the reigning standard, a handful of people would be arguing for the superiority of 700c?

late

Hi,
I love those tires and put them on my wife's bike. But she weighs 110 pounds and has never had a flat. I am a Clyde and I wouldn't dare run them.

spokenword

I was roughly 180 lbs. when I put them on in November. My average commuting kit is roughly 10 lbs. more if I also run groceries. During the winter and spring, my Gran Bois' were averaging a flat every month of commuting, and the inner casing for my rear tire started to fray, which created a small 'bubble' on the tire surface itself. That pretty much compromised any comfort that the tires had previously given.

By that, it strikes me that the Gran Bois is probably a worthwhile light distance tire appropriate for supported century rides or credit card tours. I wouldn't use it for loaded touring and I'd think twice about using it on a brevet.

Six jours

I put about 2500 miles on my first pair. I had six rear flats, which I consider a lot. Actually had one three day span where I had a flat on every consecutive day. So yeah, they are probably a bit more susceptible to flats than the average clincher, but I'd say at least half of the flats I got were the result of things like staples and nails, which are going to puncture nearly any tire. The rear tire wore down to casing at about 2500 miles, and a week later I ran over a razor blade or somesuch and opened a two-inch gash on the front, which again, would have happened with any tire. That was the first and last flat on the front, BTW.

I'm not sure about these tires off-road. I think they would be fine for smooth fire roads, but probably not so good with gravel. And even for fire roads, I'd prefer an additional 10mm of width.

Which brings us right back to the 650b. That I am aware of, there is the Grand Bois 650x30, the soon-to-be-released Grand Bois 650x40, and the -- by most accounts wonderful -- Mitsuboshi Trimline 650x38. This is a better selection of wide, lightweight tires than is available in any other diameter, as far as I know. Which is kind of funny considering how "availability" is one of the knocking points for the 650b.

Six jours

You're almost certainly right. But in all seriousness, I think 700c is a great diameter that works perfectly with the tires that the huge majority want to use. It's only when you get into big puffball tires that the problems start to crop up with 700c, and the basic idea with 650b is to use a smaller rim and a taller tire to end up with a combination of "700x23" outer diameter and a whole lot more air volume. And again, if the manufacturers wanted to invest in some 26" 30-40mm lightweight tires, then the only thing 650b would have is the cool French cyclotouring cachet, which may or may not be of any value to the individual.

USAZorro

I can't imagine the need for any tire that's more of a "pillow" than Panaracer Paselas in the widest sizes available. I recently started running an older (55 years) British bike with 27" x 1-1/4" Paselas at about 80 PSI. What a sweet ride! I float, but don't feel like I'm getting penalized with rolling resistance either. I'm sure these other tires and sizes work nicely, but I have to wonder if it isn't overkill.