Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling - 650b.....why NOT?

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?

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.

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.

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.

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

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

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.

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

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 (http://sheldonbrown.com/650b.html) 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.

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

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...

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

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.

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.

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 :)

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... 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?

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?

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?

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?

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.

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.

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.

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.

Toe overlap.

I'm currently running the 700c Grand Bois Cypres with fenders, and I have about two inches of overlap. 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.

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.

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

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.

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

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? :p

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.

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.

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.
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.

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. :)

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?

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.

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.

A great opportunity for illustration! I hate Paselas. To me they feel like riding through glue. But most people who use wider tires seem either not to notice or not to care, so that may be a good reason why 650b hasn't and probably won't revolutionize anything. Folks who get along fine with Paselas have a good selection of similarly-constructed 26" tires should they desire smaller wheels. But folks who want to run a truly lightweight puffball without frame geometry and overlap issues have, at this point, 650b as the only current option.

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. :)

Well, everyone has their own experience, but in my case, 195 lb rider, I have used these tires for about 2000 miles so far and have had three flats. One flat was a piece of wire and two were pieces of glass (wet conditions). Given that the tires do not incorporate any special flat protection, that's good performance and probably due to lower air pressure compared with a narrower tire. I typically ride these tires on brevets and permanents with about 75 psi in them. Most of the roads are chip seal but I've ridden everything from asphalt to broken pavement and even a bit of gravel and dirt in road construction zones. I see no appreciable wear on the tires after 2000 miles.

Well, everyone has their own experience, but in my case, 195 lb rider, I have used these tires for about 2000 miles so far and have had three flats.
This is about what I would expect. I think I had some pretty bad luck and that it wouldn't have mattered what kind of tires I was riding. I just put on a fresh pair yesterday, and will see what happens.


I see no appreciable wear on the tires after 2000 miles.
My front tire was in essentially perfect shape at 2500 miles. The rear definitely had a large flat area consistent with a higher-mileage tire, but on its final ride I inspected it beforehand, saw nothing worrying, and 120 miles later it was down to cord. Hopefully you won't experience any similarly unpleasant surprises.

A great opportunity for illustration! I hate Paselas. To me they feel like riding through glue. But most people who use wider tires seem either not to notice or not to care, so that may be a good reason why 650b hasn't and probably won't revolutionize anything. Folks who get along fine with Paselas have a good selection of similarly-constructed 26" tires should they desire smaller wheels. But folks who want to run a truly lightweight puffball without frame geometry and overlap issues have, at this point, 650b as the only current option.

I felt like I was sailing along, and I'm much more used to riding bicycles with skinnier tires. It seems the difference must be due to either tread pattern, inflation, or state of mind. No worries here. The more people pass them by, the better price I get on them when Nashbar runs closeouts. :)

With 650b, you need a bike specifically built them, or have to resort to makeshift solutions to set the brakes properly. It does look like it would supply a great ride, but converting an existing bike to it doesn't strike me as practical.

I really do believe it's about casings and tread thickness. I grew up on handmade tubulars, and upon "re-entering" the sport, was pretty dissapointed with the ride of clinchers. I was ready to spend $250 per pair of wide, handmade touring tubulars until Jan Heine forced me to buy some Cypres, and that made all the difference in the world. Frankly, I wish I wasn't bothered by the ride of the typical wider clincher, as that would make life simpler.

You're right about the bike, though. I wouldn't personally bother with conversions, and the frame I'm looking for (French style rando geometry, but not an original ($$$) French rando bike, and one without all the handmade ($$$, again) foo-foo) does not, for all practical purposes, exist. The Kogswell would have been suitable, but I guess he orders in small batches, because he never has anything left when I get around to asking.

So I bought a framebuilding manual. That may or may not end disasterously. :)

Checked with Bilenky?

Bilenky's website crashes my browser. My understanding of them, though, is that they build very nice steel frames in the $1000-$1500 price range. IMO, a lot of the money spent on frames in that price range goes toward carefully filed lugs and fancy finish work, which are things I don't care much about. I want a utilitarian frame with a particular geometry, for which I think I should pay $500-$750.

Of course, by the time I'm finished buying framebuilding stuff and wrecking several sets of tubes and lugs, I'll be into the $1000+ range anyway, but common sense is not my strong suite. LOL.

Bilenky's website crashes my browser. My understanding of them, though, is that they build very nice steel frames in the $1000-$1500 price range. IMO, a lot of the money spent on frames in that price range goes toward carefully filed lugs and fancy finish work, which are things I don't care much about. I want a utilitarian frame with a particular geometry, for which I think I should pay $500-$750.

Of course, by the time I'm finished buying framebuilding stuff and wrecking several sets of tubes and lugs, I'll be into the $1000+ range anyway, but common sense is not my strong suite. LOL.

Yes, I just checked their site. You're possibly even a couple hundred low - if you want lugs.

There is always this (http://www.mariposabicycles.com/650b-touring.html) :) but I also understand the satisfaction of being able to say "I did it myself". Hopefully, some day I'll be able to say that too.

Mariposas are beautiful bikes, as are Bilenkys, Coasts, Bayliss, and many others. It's not that it's hard to find a builder of essentially perfect 650b framesets -- hell, you can still have a Singer custom made -- it's that it's hard to find one with traditional geometry for under four figures. I'd have bought a Kogswell -- the P/R is the only frame I know that comes close to meeting my requirements, despite the souless TIG welding and the fugly sloping top tube, but he hasn't got any left and can't say when he'll have more.

I've long thought about learning the basics of framebuilding. This seems like the right time.

Just for the record, I rode my last 200k on August the 28th with Simon Firth (one of the builders at Bilenky) who was using 650Bs on a lugged Bilenky. I can't recall the tires but he seemed to love the comfort.

Bilenky's website crashes my browser. My understanding of them, though, is that they build very nice steel frames in the $1000-$1500 price range. IMO, a lot of the money spent on frames in that price range goes toward carefully filed lugs and fancy finish work, which are things I don't care much about. I want a utilitarian frame with a particular geometry, for which I think I should pay $500-$750.

Of course, by the time I'm finished buying framebuilding stuff and wrecking several sets of tubes and lugs, I'll be into the $1000+ range anyway, but common sense is not my strong suite. LOL.

I've never had problems with their website, have you tried using mozilla firefox as your browser?

Actually, it costs a lot to operate a shop and pay skilled craftsmen to weld and miter tubes. Tubing also costs money and it's more difficult to produce a quality TIGed frame that wasn't made in Taiwan for under $1000 than you think.

From Bilenky's website:
http://www.bilenky.com/images/Frames.gif

I've never had problems with their website, have you tried using mozilla firefox as your browser?
I'm at work, so my browser is whatever I'm told it has to be. :)


Actually, it costs a lot to operate a shop and pay skilled craftsmen to weld and miter tubes. Tubing also costs money and it's more difficult to produce a quality TIGed frame that wasn't made in Taiwan for under $1000 than you think.
Oh, I'm not knocking the prices charged by Bilenky, or any of the other builders. I've owned some very special and expensive handbuilt frames and they are certainly worth every penny. But "special" is not what I'm after for this project. I want a frame that I can put a zillion miles on and travel all over for brevets and ride off road and in the rain and mud, etc, etc. If I were to do that on an expensive piece of art I'd die a little inside with each new chip, dent, or bloom of rust.

So this time, Taiwan and TIG -- or homemade from $100 tubing and $50 worth of lugs -- is exactly what is called for.

So how about we give this poor fellow his thread back, anyway? :lol:

I don't know, should smaller people ride smaller wheel bikes. Other than that, with all the improvements in quality control, the materials and fabricating of any size bike should be sufficient.

What I don't understand is why RUSA never instituted a standard issue headlight/tailight setup that would serve as the "default setup" for anyone riding Brevets. You could have more lights , but never less, that way riders could swap out lights in emergencies (like inner tubes/tires) and the club would be assured that everyone had at least one set of acceptable lights.

For an average sized person, 650b is more or less the largest wheel size that will let you ride a 40mm tire (with fenders) and have no or minimal toe overlap (a low trail geometry helps here, too).

I think it's really that simple. Start with the average sized cyclist, the desire to run tire size that gives a nice cushy ride (which the BQ folks have pretty much shown could also be a *very fast ride*) and 650b pretty much falls out as a desirable wheel size.

That's why I think it's more than a fad. 650b. It fits.

(And BTW I just put a 50mm Marathon Supreme 26" on my XO2. Now that is an intriguing tire. Supple, and supposedly:

* low rolling resistance
* high puncture resistance
* good wet adhesion

If you don't mind toe overlap (or you're really big :-) it's available in a 40mm 700c size....)

(And BTW I just put a 50mm Marathon Supreme 26" on my XO2. Now that is an intriguing tire.

*

Let me know what you think of that tire. I am fascinated by it, and have been bugging Schwalbe to make it in a 30 or 32c.

Let me know what you think of that tire. I am fascinated by it, and have been bugging Schwalbe to make it in a 30 or 32c.

Well it is available in a 35mm width - is that close enough?

http://schwalbetires.com/node/1201/ok

So far I've ridden it only in more or less dry conditions. Very cushy. If the BQ guys are right, the low rolling resistance compound combined with supple sidewalls should make it fast. It does seem faster than the old Conti town and country I was running, but that probably doesn't mean much.

Oh, and it went on my Velocity Aeroheat rims relatively easily. *That* was a happy discovery. (I actually put it on backwards, took it off and put it back on right. So I'm pretty sure about the "on off performance"... :-)

I have long reach brakes that won't go over 32c. Maybe next year

I run 26" wheels on a steel Mercian tourer.
I recently tried a 40yrd 'roll' test alongside my son. he was riding an old racing bike with 23mm tyres, I had 1.75" slick on my front and 1.5" pasela TG on my back.

After 40yrds, I was a whole bike length in front of him.

How much more do you weigh? :p

BQ is big on the "roll-down" tests. I'm not too sure. I understand their argument against the steel drum, and for "real world" conditions, but at the same time, I wonder if it's possible to adequately control for all the variables induced by simply rolling down a hill on a bicycle. The fact that their results have been pretty repeatable is encouraging, but still...

Ride Report on Grand Bois Cypres 700x30:

Rode these 1100+ miles, including a 320 mile training ride before PBP, and on PBP itself (to Dreux, where I DNF'd at about mile 720). No flats. No wear on front tire; rear tire just starting to show wear. These tires ride like a dream. Even the worst chip seal disappears under them. And rolling resistance is noticeably better than my next favorite tire, the Panaracer Pasela. FWIW, I weigh about 200 pounds, and bike plus gear, food, and water weighs about 50. Plus, after PBP I did another 70 or so miles fully loaded for touring; rack, panniers, tent, sleeping bag, cooking equipment, so total weight of about 280 pounds. About three days before PBP, I pumped the front tire to about 70 pounds and rear at about 95; never touched the tires again until I deflated them to pack in the S&S case.

And rolling resistance is noticeably better than my next favorite tire, the Panaracer Pasela.

Don't let USAZorro hear you say that! :)

Just for the record, I rode my last 200k on August the 28th with Simon Firth

I think you mean July 28th, no?

Rode these 1100+ miles, including a 320 mile training ride before PBP, and on PBP itself

I've ridden the Gran Bois for most of the season, 300, 400, 600 km, PBP and numerous other rides including gravel/dirt roads in the Olympics. Only 5 flats all year and 2 were do to goatheads in Wenatchee, WA, and 2 were due to bad tubes. So, not bad I'd say.

The ride is really sweet, but I did have a new fork built to accommodate the toe clip overlap issue (which I hate). I'm glad I have a bike that can take them (Riv Canti-Romulu (http://www.mountainbike.org/pages/jon-muellner-cycles/bicycles/riv-canti-romulus.php)s).

My next bike will be 650b and I have little concern it will cause any problems, I always carry a spare on brevets of any distance and think it'll be fine. I want more cush and less concern and the roads I ride aren't getting any better soon.

Jon

How much more do you weigh? :p

BQ is big on the "roll-down" tests. I'm not too sure. I understand their argument against the steel drum, and for "real world" conditions, but at the same time, I wonder if it's possible to adequately control for all the variables induced by simply rolling down a hill on a bicycle. The fact that their results have been pretty repeatable is encouraging, but still...

It was just a basic test, I didn't expect, over 40 yards, for there to be much difference. I was a bike length in front at the bottom of the slope, so weight was not a factor (and we are similar weights anyway).

A whole bike length, over that distance, is a *huge* amount. I've ridden down a long gentle hill with my son before; I freewheeled, he had to pedal to keep level. I'm not convinced that skinny tyres have lower rolling resistance on real roads.

At ordinary speeds the compliance of the tire is going to help. The low pressure and thin casing of 650b tires make them suprisingly lively. Get fast and
skinny will have lower wind resistance; and be quicker to accelerate.