[CR]Requested Clarification: 700C & 27" / wheel & tire sizes / framefit -- sorta for the less-experienced


Example: History

From: "tom.ward@juno.com" <tom.ward@juno.com>
Date: Tue, 25 May 2004 21:39:42 GMT
To: classicrendezvous@bikelist.org
Subject: [CR]Requested Clarification: 700C & 27" / wheel & tire sizes / framefit -- sorta for the less-experienced

Mr Collins wrote: <Could someone clarify for me the basic distinctions between 27" and 700c wheels? It seemed that in the discussions about 27" sew ups, there was size overlap. Might 700c wheels fit bikes made for 27" and vice-versa? I always thought that to be impossible. If so, how do you know if a frame is for 27 or 700? I had no interest in this until getting on this list, now I seem to be in the beginning stages of addiction and am bidding on my first (near)classic. Oh well, one more guy to drive up prices.>

Haha!--and welcome; you may be hooked already--"abandon all hope, ye who enter here". Don't worry much about driving prices up, unless you're planning on piling onto the already super sought-after marques or the truly rare! A lot of good stuff is out there inexpensively, if you don't have to have the item that everyone else wants this week or season--or the items that are virtually one-of-a-kind. Frankly, I feel that at this point it is all still quite possibly far undervalued. We are just a tiny schism amidst a sea of fun old bikes. I suspect many are still under cover and will seep onto the market--and this list is nothing if not a network.

Okay now, onward to the heart of the matter: I recommend checking into Sheldon Brown's website for a thorough discussion of wheel and tire sizing. He's been there and done that. In fact, as I'm getting this in digest, you (we) may have already heard from him personally, as this seems to be one of the areas where he is most effective and active. However, at the risk of being redundant, I will herein shoulder a basic talk about the subject. Veterans may skip this post--or check how I do.

The recent confusion among some on the list as to 27" tubulars is yet another item that has to do with long-established British popular cycling syntax--which I love, by the way, although I'd probably use all french terminology if I only could, and next week it will be only Italian terms. Kidding! Bear with me here. A relevent point is that the British idioms (seemingly anglo-specific cycling terms, one of which I am about to talk about) have extremely deep roots, often '30s or beyond, whereas a majority of U.S. bike-boomers came later to the lightweight game...sometimes failing to notice the details of what preceded them--details which sometimes weren't readily available to them. That's fine, it just represents another divergence on the cycling "tree"--and some of what we do here is bridge across the various branches of both time AND region. Again, bear with me...now, on to the substantive stuff:

A very precise way to consider tire and wheel size is to measure the diameter of the "bead seat area"--where you'd stick the glue if you're considering a rim for tubulars, or literally where the bead goes for a "wired-on" (clincher) tire. The imprecise, shorthand way, popular over the years (check into 1950s UK cycling magazine ads) was to speak of the nominal outside diameter. In reference to lightweights, one would speak of 27" sprints (i.e. 700C tubulars, because the outside diameter of a 700C tire and wheel is about 27"), and 28" which meant 27 x 1 1/4 clinchers--28" being the nominal outside diameter. You could speak this way at the time because in England because these were the two common sizes of tire and they were of enough different type that people knew what you meant--a more technically detailed name for the tire (tyre) wasn't required. This shorthand is a wonderful example of why cultural studies within cycling "enthusia" (am I coining a term? The varied forms that the cycling passion takes, cycling sub-cultures, in a sense) are absolutely necessary. Same thing will be required to study current things in the future. To have any great understanding of the old bikes requires an open and inquiring mind as to how not only they were made and operated, but how they were spoken of by the respective original regional and national (or use-defined, like racer vs. randonneur vs. commuter) populations that used them. So welcome to the passion and the research--and the U.N. summit meeting!! Get ready to learn a little Italian, a little French, etc.--customs as well as language. It's a large part of the fun, actually. Where would I be without the term and concept of the "randonneur"? Let alone "derailleur"--though the British "rear mech" is highly evocative. Both mere slang and highly technical terminology add greatly to our understanding of what's what--especially when "foreign".

Do check out the discussion of wheel & tire sizing at http://www.sheldonbrown.com --credit where credit is due, he does a good job of bringing order to chaos in that online article.

As for fitting 700C wheels to frames on which you have 27 x 1 1/4 clinchers (and vice-versa), you certainly may do it, it's done all the time. Okay, well not in every circumstance. The limiting variable is often the "reach" of the brakes. They simply need to be long enough to reach the braking surface of the rim. If the brake caliper arms are too short, you can use a drop-bolt (or just buy long-reach brakes). If you've got a tourer with cantilever brakes, you also may be stuck with the wheel size you've already got....

Older frames were often intended to use either 700C (27" sprint) or 28" clincher (27 x 1 1/4) wheels--you'd switch wheelsets based on what you were doing that day--perhaps (but not necessarily). At some point far back along the way, 700C clinchers (same nominal outside diameter as the tubulars) started to come in to help muddy the waters...wow, I could go on and on, even without really getting into 650B, 650C, 26 x 1 3/8....

Despite the length of this post, this is really far too brief to do justice to the subjects at hand. I'm just covering this in the broadest way. Again, Sheldon has really worked on this. I hope the more experienced among us won't feel I've blown it in some way with this attempt at a short exposition. If so, I certainly don't mind being corrected. A student of traditional cycling must also be a student of the competing standards of dimensions and measures--and must be prepared to be in error once or twice. Have no fear! There are some discernable patterns amongst all the overlapping or seemingly cross-purposed bits. Cycling terms and measures form a language of their own. You'll soon be bilingual, if not bilaminated--and will be swapping wheelsets like there's no tomorrow.

Thanks--and with love to all of you hold-outs of one kind or another-- Tom Ward castaway on the desert isle of Manhattan NYC