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Recreational Cyclocross and Gravelbiking This has to be the most physically intense sport ever invented. It's high speed bicycle racing on a short off road course or riding the off pavement rides on gravel like :The Dirty Kanza". We also have a dedicated Racing forum for the Cyclocross Hard Core Racers.

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Old 06-21-06, 11:46 AM   #1
mtbcyclist
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Thinking of coverting a road bike to a cyclocross bike... tire thickness for gravel?

Was thinking about building a cyclocross bike out of an old road frame. The bike would be used to ride on road, and gravel trails. Would be used primarly for commuting. So with that being said I was thinking that 30-32mm tire would work good for gravel (crushed limestone)? I can't go too fat as it is an old road frame so the spacing in the seat & chain stays is a limiting factor. Are cyclocross rims and road rims the same as far as dimensions? Figured I could get away with road rims since I am just doing road & gravel road and not trying to hop logs or do obstacles. I would imagine road rims are not as strong as cyclocross rims. I would think cyclocross rims are made more for taking a good beating. Has anybody tried this before with success? Any suggestions would be appreciated.

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Old 06-22-06, 08:07 AM   #2
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I would recommend 32mm, but the important thing to watch for is tire pressure. I had my tires inflated to 90 psi for I was riding mostly on asphalt. When I hit the the hard gravel of the trail, it was just a tad too much air. Larger bits of rock and gravel would deflect the front tire off where it was pointed. Lowering the psi to 65-70 would make things more plush and stabilize your steering. As for rims, haven't measured mine, but sheldonbrown.com has recommendations for proper rim width for the tire you're using. YMMV
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Old 06-22-06, 07:04 PM   #3
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Thanks for the tips. I think this is very dooable based on another thread talking about riding though Kay park in the mid west on crushed limestone with road bikes.
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Old 06-22-06, 07:46 PM   #4
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I'm not sure what the gravel is like in your neck of the woods, but here in Washington DC, we have gravel on the Capital Mall from the Washington Monument to the Capitol Building. It's a long stretch that I regularly blast through on my CX bike, using 30cc Ritchey Speedmax's jammed to 90psi. The gravel here has a firm base with small to medium pebbles, and my tire setup handles it fine. Reality is that there are many tires out there, and I prefer the Ritchey's not just for their light weight and low rolling resistance, but also because being able to inflate them to 90psi versus just 70psi as is the case with my Hutchinson allows me more options with what I want to do with the tires.

Also, there are no real CX-specific rims, but rims like the Mavic Open Pros and the Kyseriums seem to find much favor with the CX racers. In fact, you'll see CXers racing with the same blingy deep-dish carbon rims that roadies use. I would reccomend going through your local bike shop, and try to find the employee who is most CX knowledgabe, and find out from them. I did that when I got my Ritcheys, and had my LBS check to make sure that my Gippiemme rims could hadle the higher psi rating of the tires.
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Old 06-26-06, 10:59 PM   #5
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I did my first season of cross on an old steel road frame with 32mm Ritchey Speedmaxes. I'd have come to a quick stop if the back wheel ever went out of true, and I prayed for dry every race, but it ended up working just fine for me.

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Old 06-29-06, 01:57 PM   #6
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Thanks guys. Just the info I was looking for.
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Old 07-04-06, 10:10 AM   #7
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If you plan to commute and not abuse your bike (jumps and crazi mtb-like moves) on some easy to moderate off-road trails I think you'll do just fine with road rims and some decent CX tires. Watch out for the tire width (don't go too wide). If you don't have cantilever brakes the room between the brakes and tires/rims might be to tight. There are plenty of good cx tires that are sort of "narrow" (still not so narrow as road tires) and they offer fast ride on pavement and reasonable comfort on rought surface. If you're not planning on doin g serious CX on this converted road bike I'd suggest some sort of CX racing slicks... they tend to have low central profile that creates less roling resistance on pavement and hard pack but enough grip on dirt/hard-pack. In addition stronger side knobs help with cornering on off-road. Check out cyclocrossworld.com and their tire section for good overal choices and references.
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Old 07-14-06, 03:48 PM   #8
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I am new to the sport and have been intrigue by cyclocross. Can I take just about any road bike and put some knobbies and call it my cyclocross bike. Is it that simple or is there something I am missing. Thanks for helping out a newbie!
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Old 07-14-06, 08:11 PM   #9
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Also watch out for tire clearance near the seat tube... a friend of mine tried turning his Giant OCR-3 into a cross bike and 32's hit the seat tube
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Old 07-18-06, 08:12 AM   #10
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Quote:
Originally Posted by normdzn
I am new to the sport and have been intrigue by cyclocross. Can I take just about any road bike and put some knobbies and call it my cyclocross bike. Is it that simple or is there something I am missing. Thanks for helping out a newbie!
Not much more to it than that, except...

Modern road bikes seem to be more and more specialized crit machines with twitchy fast steering and no tire room between the forks, stays, or even between the tire and seat tube. Make sure you've got plenty of room. At least enough so that every leaf and speck of mud you pick up doesn't rub on every wheel rotatation. Older bikes are better that way, some piece of steel from the mid 80s is about perfect for the job. Old touring bikes already have canti's - they tend to be low in the bottom bracket so mind the pedals.

If you run tires wider than 30-ish you may need to let some air out to get them in and out past caliper brake shoes.

Get a slightly taller, shorter stem and go ride.

Ron
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Old 07-21-06, 02:16 PM   #11
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So ive been lurking on the cx forum for a bit and thinking about turning my late 70's early 80's fuji sagres into my first cx bike I live in northwest arkansas where there is a huge mtb scene so im sure i will have many trails to ride. I mostly ride fixed gear in town and was thinking about doing the cx bike singlespeed or fixed any input would be helpful i.e. which tires to use should i get new brakes or just scavenge some
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