Converting old road bikes to cx

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Permalink Reply by Chris Mayhew on September 19, 2010 at 3:09pm

Nah, those older bikes have a lot of clearance on them. You'll be limited by your brake calipers as to what tires you can run. Get some bar end shifters if you can and appropriate cross gearing. But it should be a good project for sure.

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Permalink Reply by Chris on September 19, 2010 at 3:24pm

I was thinking of doing the same with my old Bridgestone RB. Brake clearance is the only real issue, as the frame and fork will take a 700x30c if I remember correctly.

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Permalink Reply by Nathandor on September 19, 2010 at 11:39pm

Hi , It is possible but all depends on the specs of the bikes.
What kind of wheel set and brakes do you have? The trick is to get the biggest cyclocross tires that can fit in you breaks fork and frame. Modern road frames can fit 25 mm tires' width and few 28. Older might accommodate bigger size.
.Brakes and frame are the bottleneck. Another problem is related to old wheels (old 28) - for them it is difficult to find new CX tires.

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Permalink Reply by Ryan Cousineau on September 20, 2010 at 12:31pm

You're not crazy. My first dedicated CX bike was an early-80s Taiwanese-made ("Bianchi") steel frame.

If you've got long-reach brakes on the frame you've probably got enough clearance for most CX tires. Measure the clearance at the rear-wheel and brake, and use the frame with the most. Most frames of this era ran the rear brake cable in an enclosed housing on the top of the top tube. If not, you'll want to pad the cable stops.

The front wheel is much less critical, because you can change the fork. In fact, going to a CX fork is a cheap and cheerful first upgrade. If it's a typical 52/39 road double, you'll basically race on the small ring, but that's not a problem. Most triples are likely to be

Other than that, go as your budget and desires allow. Here's, in rough priority, the changes and upgrades I go with:

Must do to enjoy this:
-CX tires
-adjust brakes to fit
-consider saddle change, depending on what's on there

May have to do:
-front fork change (depending on front brake clearance). When you change out the fork, I'd consider doing the threadless conversion (which means new fork/headset/stem and probably bar), which doesn't have to be expensive if you shop carefully (no Ritchey WCS for you) and lets you move to a stronger, slightly lighter front end.

Nice to have:
-chain watcher (easy and cheap upgrade)
-cx levers (if you want them, and if you're changing the bar out)

Next:
-Given the price of barcons and older used (say, 9-speed) brifters, why not just go brifters? Anything above 7 speeds pretty much requires a freehub rear wheel, so that's another worthwhile change, especially if you're heavy or clumsy, since you might be pushing up against the limits of most old freewheel-hub axles. If you've got a good road bike you don't ride during CX season, this is a good chance to make that rear wheel do double-duty: buy a set of brifters and maybe a cassette (if you want to be cheap and run 9v), and you don't need to buy the rear wheel. This sort of re-use is where doing a CX bike on the cheap can actually save money.
-going to a freehub means 130 mm rear spacing. Cold-setting the rear end of a steel frame is fussy work, but not impossible for the backyard mechanic (http://www.sheldonbrown.com/frame-spacing.html) but even easier is not bothering: a 126mm frame can be forced to take a 130 hub with a bit of elbow grease, and the only problem is that rear wheel changes will be a dozen seconds slower and a bit fussy. Don't bother leaving a rear wheel in the pits :).
-once you go to indexed whatever, you'll have to change the rear derailer, and probably the front one. Just get the cheapest MTB rder you can stand, and a Sora or TY-2200 or used for the front. Almost any indexing Shimano rear derailer will work with almost any SIS setup (the exceptions are mostly very early and very recent Dura-Ace).

At this point, it's worth considering whether the next thing to change would be...the frame. The next "easy" upgrade is to change the rings (and maybe the crank and BB) to something CX specific. And then the only identifiably road-ish part of the bike would be the rear brake, and arguably the chainstay bridge. Unless you're really in love with the frame, a cheap new CX frame will cost less than brazing canti posts (or, heh, disc tabs...not actually recommended for a lot of reasons) on. OTOH, this is probably the least important part of the bike, CX-performance wise. You can open up a single-pivot long-reach brake really wide.

Here's a photo of my heavily converted steel Bianchi:

http://www.flickr.com/photos/rcousine/353507328/in/set-721576231122...

Brifters, freehub rear wheel, super-ghetto top tube pad, new crank, threadless front end, and a hole drilled in the stem so it can serve as the cable stop.

If you go through that "bike random" photoset, you'll see some other tricks, like a similar conversion of a cheap Motobecane, frame respacing (the dropout alignment tools are a big time- and sanity-saver), and converting a Shimano threaded headset to 1" threadless.

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Permalink Reply by myron melnarik on September 20, 2010 at 10:24pm

Thanks for all tips, I'm gung ho to try this...

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