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I'll be moving in the near future from a wide open rural area with open, expansive country roads to a more suburban area with traffic issues but a few offroad trails available for riding. My question -- and probably a silly one -- is: is it at all recommended to outfit a separate set of wheels with CX tires for my road frame for trail riding at a fraction of the cost of a new CX bike or am I putting my road frame at unnecessary risk trying to save some money?

I'm not imagining I'm going to be getting into legit mountain biking (just yet) and only ride for personal fitness and the enjoyment of it. I've seen threads here asking the opposite (CX for Road), but nothing this way.


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It depends on how trail-y these trails are and how svelte your road bike is. If they're just fire roads, I'd be comfortable taking something like a Trek 520 on them quite easily (mainly to run >28mm tires). If there's jumps or something, no. – Batman Feb 11 at 17:12
The biggest issue is tire clearance especially on the chainstays, make sure your frame can accommodate >32mm tires. – azer89 Feb 11 at 19:12

3 Answers 3

Personally, if your road frame is an out-and-out road bike - I would say you will be faced with several issues.

  • strength of your frame

Not only will this stress your frame - it may also fatigue the frame. And may cause sudden and catastrophic failure.

  • tyre clearance

Most road frames will not take a tyre greater than 28mm. Some no more than 25mm.

  • comfort

The seating position and reach could be altered to make more comfortable - but it will always be a compromise.

  • Geometry

Road bikes have different geometry to CX bikes. Lower bottom bracket offers lower clearance, steeper head angle makes the ride more twitchy.

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For many bikes, generally, you won't get much more than 2 mm in tire size more than what shipped with the bike/ – Batman Feb 11 at 17:13
Tire clearance issues don't always come from where you expect either. Some of the road frames I've owned would accept 40c tires. However, I couldn't get anything bigger than 30c to fit inside my Shimano brake arches. – Suspended User Feb 11 at 17:32

You might be better off with one of the new bikes coming out with "gravel" or "all-road" geometry and clearance for ~40c tires. They're intended for the type of riding you describe. Current examples include the Raleigh Tamland and Willard, Salsa Warbird, All-City Space Horse, and Kona Rove. These bikes tend to have lower bottom brackets and longer wheelbases, giving them better comfort and handling on and off pavement.

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Depends on the trails and the type of riding and how big of tires you can put on the road bike.

Based on frame and brakes you are probably limited to 28mm or 30mm. Still a lot better than 25mm.

If you are dealing with sand and/or big sharp rocks then 30mm is not enough.

As for mud just don't ride mud. Mud need excess clearance.

So you might as well just go with touring type tire and give yourself a bigger footprint to deal with traffic issues.

It is not going to be CX bike - the best you can do is beef it up.
What I am saying is you probably can't beef it up so much that stops being a valid road bike. Ride it and get a feel for if you want to get a second bike. You may decide you want to leave your road road and get a second mountain bike.

I would not go with a separate set of wheels. Your brakes will probably not take a wider CX rim so you are just going to get a beefier road wheel. A beefy set of wheels is going to be $400 and you should not be riding a road frame that hard.

Look for a used CX. Season just ended and you can find some good deals.
And CX varies a bit - a pure race may only take 35mm tires. Get one that will take 38mm or larger.

And don't rule out a mtn bike - you can find some decent used mtn bikes for $400. You can throw $400 into your road bike and it is still not going to be a good trail bike.

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