SF Cyclotouring

Ride reports and other ramblings from a San Francisco cyclist.


650B, Is It For Me?

R(650)B-1 at Big Rock, side view


I've been curious about the 650B wheel size since first learning about it via the iBOB and Kogswell email lists. My initial impression was that a 650B conversion done on an old tight-wheel-clearance racing frame was a neat way to repurpose the bike by giving it clearance for wider tires and fenders which it otherwise lacked. Many folks have offered the opinion that the 650B wheel size represents a "holy grail" of sorts, combining the best attributes from 700C "road" wheels and 26-inch "MTB" wheels. Several 650B-specific models of new bicycles have come on the market in the past couple of years, along with many framebuilders taking orders for custom frames spec'd for the 650B wheel size. I finally decided that enough was enough and -- wanting to see what all the fuss was about for myself -- I recently converted my 1993 Bridgestone RB-1/7 from 700C to 650B. I swapped the original 700C wheels and 23mm Continental tires for a 650B wheelset comprised of Velocity Synergy rims, Shimano 105 hubs, and Rivendell's Nifty Swifty tires. The original Suntour Superbe Pro short-reach brakes were replaced with Rivendell's Silver super-long-reach brake (re-badged Tektro R556 with upgraded KoolStop brake pads). I changed the SKS P35 fenders for a set of wider P45 mudguards. Today I spent 75 miles on the bike, and these are my impressions.


The 650B tires used in this conversion measure approximately 33mm in width and leave about 3/16-inch of clearance at the RB-1's chainstays. Wider 650B tires exist, but chainstay clearance would be an issue with this frame. This in itself is interesting, since the limiting factor for wider 700C tires with this frame was brake-arch clearance, yet with 650B wheels it is chainstay clearance. In fact, despite installing fenders, there is still excess clearance under both brake arches, implying that taller tires could be fitted (if such a thing existed). The road manners of these tires reminded me very much of a set of 26-inch mountain bike road slicks I've used in the past: Performance Bicycle's Forté City ST MTB tire. The tires don't seem excessively heavy and I didn't notice any large differences in acceleration or rolling resistance between these and the previous 700C Continentals. As expected, road bumps and irregularities were better absorbed with the wider tire. Trackstanding was perhaps slightly more difficult with the wider 650B tires due to the increased pneumatic trail. Overall, the experience of riding a wider tire on the road felt similar to riding my cyclocross bike with its 700x35 hybrid-type tires on pavement -- bump absorption and ride qualities were comparable. I should also mention that neither before nor after the 650B conversion was foot/fender interference (TCO) an issue.


The Silver brakes were easy to install and set up. Although I didn't toe the brake pads, no squealing was evident. As others have written, these brakes do seem to flex more than the stock calipers, presumably due to their increased caliper-arm length. Confidence in stopping power is somewhat diminished as a result. The special quick-release mechanism employed on these brakes does allow them to open up enough to facilitate removal of wheels fitted with wide tires.


The handling qualities of the RB-1 weren't significantly affected by the change in wheel size. Generally speaking, the bike rides the same with 650B wheels as with 700C. The effort required to ride no-handed wasn't significantly changed. With 700C wheels, a full Banana Bag strapped to the handlebars of this bike tended to produce a front-end shimmy at moderate speeds (10-12mph); this was unchanged with 650B wheels as well. Although the BB height dropped by a full centimeter (268mm down to 258mm), the bike's new lower center of gravity was undetectable. Two negative characteristics were introduced: First, the bike felt a bit less stable overall during the first few miles, although this sensation diminished notably during the course of the ride. Second, the bike seemed to want to "turn in" during fast sweeping descending curves -- before the conversion, the bike was less willing to turn, requiring great concentration to maintain a line through a curve; with 650B wheels the bike seemed to want to "fall in" to the curve, requiring focus to keep it from doing so.


I'll admit I've been skeptical of the whole 650B phenomenon. Several people have opined that 650B wheels/tires offer some sort of magical carpet ride, yet I've maintained that good quality, wider tires should offer less rolling resistance and (obviously) a smoother ride (than skinny 700C tires) regardless of their diameter (within limits of course). My experiences with my own 650B bike reinforce this argument, with ride qualities -- at least in the "plump equals smooth" department -- reminiscent of both 26-inch and 700C bikes I've ridden with similar-width tires. Converting this bike offered no mystical revelations for me; the sole pragmatic advantage is that I can now fit wide tires and fenders, the benefits of which are immediately explicit. Would I perform this conversion again? Probably not. The money that I spent on replacement wheels, tires, and brakes equals the cost of a quality used frameset and also approaches the cost of a budget new frame -- in other words, I could've just as easily purchased a different frameset with improved clearance for wide 700C tires. Also, as I mentioned my RB-1 now sits a centimeter lower -- this means that I could actually move up to the next size frame since the standover height has been decreased. In other words, if I was going to 650Bify a bike, it would've been better to start out with a frame that was slightly too tall so that the resulting bike ends up properly sized, post-conversion. That said, I'm going to leave my RB-1 in 650B-mode for the time being...those wide tires come in handy for the potholes, ruts, grooves, and streetcar tracks in the city streets I've got to traverse to get to the good riding in the country!

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Oh yes I did!

front brake and fender
Originally uploaded by jimgskoop
Just finished (finally!) converting the ol' RB-1 to 650B...gonna try this thing out and see if/how I like it. I definitely like the looks of these bikes with the stout tires, but I still gotta see if I like the ride...that'll come tomorrow, stay tuned for an update! FWIW, the BB is about 1cm lower than before, the BB height changed from 268mm to 258mm.

Full set of conversion photos here.

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I've recently written about how I've acquired a 650B wheelset to convert my RB-1 to this old/new-fangled wheelsize so I can see what all the fuss is about. I bought the wheels used, supposedly with only a few hundred miles on them, and the fact that there's nearly zero brake-pad markings on the rim sidewalls backs that up.

But DAMN these wheels were in sorry shape! I've spent some time over the past week re-tensioning and re-truing them because the spoke tensions were horribly unbalanced and too low, overall. I borrowed a friend's Park TM-1 spoke tension meter* so I knew exactly how tight I was making the spokes.

The wheels have "QBP Wheelhouse" decals on them, and I must say that whoever built them was apparently drunk. The front wheel is laced with 2.0 straight-guage spokes while the rear has 2.0/1.8 butted spokes. The spokes are DT, but are fastened with an apparent mix of DT's stubby nipples, random standard nipples, and a few longer ones as well. I swear there's a nipple in there to suit anyone's tastes! I don't know if all the spokes are of a uniform length and the builder just used whatever nipples were within reach, or if some of the spokes have been replaced, or what, but it's a crap job. IF these wheels came like this new from QBP, I'd've sent them back!

None of this is that huge of a deal -- everything's usable/fixable, and I still feel that I got a pretty good deal on these wheels. It just meant a delay in my 650B project since I'd been expecting that I could use these wheels immediately. I've still got to repack/readjust the wheel bearings and swap the cassette over from the current rear hub before I can mount these wheels to the bike, and then I've got to swap out the brakes. Hopefully I'll be able to get to that this weekend.

...and hopefully after all that work, I'll actually like this 650B thing! Who knows?!?

Caveat emptor, as always, I guess!

* I should add that it's been somewhat of a trip using the TM-1. My lender friend warned me that I'd be tempted to check all my wheels with it, and that I should resist that temptation. Of course I didn't, and I now know that virtually none of my wheels are at the "right" tension, even those built by very reputable builders! More significantly, I've always tensioned wheels by pitch, and poo-poo'd those who've argued against that technique. Now I know that, while pitch can be used as a rough guide, it is definitely NOT an accurate way to detect spoke tension, especially if comparing spokes of different thicknesses!



Twenty-Six, Redux

Originally uploaded by jimgskoop
Yesterday, Carlos and I enjoyed a short ride through the Marin Headlands. We've done this ride several times before -- it's always great fun and an enjoyable way to get the blood pumping, especially on a warm sunny day . The thing that made this ride somewhat noteworthy was that instead of riding my cyclocross bike, I rode my mountain bike -- a bike I haven't ridden in nearly seven months (the bike was having some chainsuck issues and I hadn't made time to address those until recently)! I was wondering whether the bike would feel odd after all that time, since all of my other rides are rigid 700C drop-bar bikes with much skinnier tires and level top tubes. I'm happy to report that this was not the case. Well, maybe it was for about 5 pedal strokes, but after that it was like welcoming the return of an old friend. A green friend, in this case.The typical wide, knobby tires of a mountain bike always fortify my confidence when riding off-road, and the 2-inch-thick tires on my bike certainly helped when I fudged my line during the high-speed descent into Tennesee Valley -- I didn't brake enough before dodging a group of slow-moving cyclists on the trail, and found myself headed towards a deep rut and a likely face-plant. Miraculously, the bike found its own way out of the trouble, and despite my muttered "Oh shiiIIIT" and frantic SPD-unclipping, I remained upright. Later, after blasting down Tennessee Valley Road, I came upon a usual trip-up on the shortcut trail to the Mill Valley Bike Path: a drainage pipe laid across the path with a small, rocky drop off on the other side. Normally I'd have to put a foot down here, but this time I just followed Carlos' line and the Bonty rolled on through. Usually I loathe riding twenty-sixer knobbies on pavement, but as we pedalled through the streets of Sausalito, despite the audible buzz of the tread I noted that pushing the pedals didn't seem any harder than normal and the bike seemed to roll happily enough. Finally as we climbed up towards the Golden Gate (a climb I usually dread) I found that the summit came more readily than I'd remembered, and certainly more easily than I'd expected, given that I'd not ridden for the three weeks prior. Clearly i need to ride this bike more often! A final thought: I'm really glad that, on the bikey forums I seem to be addicted to, mountain bikes in general, and new mountain-bike technology in specific, aren't discussed more often and in-depth than they are, otherwise I'd probably get the urge to tweak this or try that -- instead I can just continue happily riding my thirteen-year-old bike in ignorant bliss! My Bontrager is perfect and I don't want to change a single thing about it (other than maintenance issues, and maybe a different saddle, ouch)!

Although, if anyone has a Bontrager Ti Lite frame in a size Large they'd sell cheap, do let me know! ;)