Besides actual frame size, it seems like tire clearance is one of the most limiting factors on the bicycle frame. You might be able to change out every component on the bike, but still be stuck with 25mm tires.

How come the vast majority of consumer bikes in the US have such tight clearances on anything that isn't a mountain bike? Is this a result of the racing industry's effect on the other 99.9% of riders? Even many bikes geared towards commuters, tourists, and weekend riders have limited tire clearance.

Cheers.

None whatsoever. There's an illusion that the "tight" fashion makes a bike faster. Unless you're trying to beat a world record, having clearance for a bit of mud, leaves or fenders and proper width tyres has no negative impact.

None as far as I can tell. Perhaps for a racer there is some miniscule aerodynamic or braking advantage. I've got a Serotta fork that doesn't even have room for a 25 mm front tire, so I ended up replacing it with one with more clearance.

Seems like a pretty open-ended question. Based on your need, then yes and no.

Is more clearance better for MBing? While it would see that mud and other small debris would clear the gap, what about wedging in a stick or branch and then getting thrown? Wouldn't a smaller gap force the object to snap?

If you are commuting, then obviously you want a solution that allows you to ride on the tire of your choice. There is no such thing as "proper width tires" though. That's perception. I know people that can commute on 23s as easily as they could on a pair of 2.55 MB tires.

I like the clearance for weekend riding on my CAAD with 23s. I like the clearance on my Araya with 32s.

A shorter wheelbase has slightly faster handling which feels faster for a customer test riding. There might also be a miniscule difference in frame stiffness.

Whatever it is, it's a bad tradeoff even for racers who are starting to recognize that wider tires can be faster, but they have to ride what their sponsors think will sell.

I think the "benefits" for a pure road bike are very minimal. The only things I can think of are - shorter reach brakes can be smaller and lighter, and design wise the frame and fork can be ever so slightly more compact, lighter, maybe more aero. Mainly, I think people designing pure road bikes never imagined anyone wanting wider tires and designed everything with that assumption.

It seems like a lot of manufacturers are making bikes and frames to accommodate wider tires. My Kona commuter bike can take pretty wide tires and pretty much everything by Surly is designed for wider than usual tires. There are lot of options out there.

Very good.

Um, no. Snappy handling isn't a bad tradeoff when you're looking for snappy handling. Take a 180 at 20mph or more in a crit and tell me that it's better to give up a short wheelbase in favor of being able to mount 35c tires.

Also, most race bikes are setup to handle 25c tires, which is what they mean when they say wider may be faster. Sometimes they even mean 28's.



There's a wide variety of bikes out there with good tire clearance. Quit blaming the sport side of things for you not having selection. It's not a conspiracy out to get you. I had absolutely no problem finding a frame to fit my 700x40c studded nokians with room for fenders and daylight.

I think it is a racing thing. The shorter geometry should allow less flex, and probably when it comes down to it, weight (Short vs long stays).

It is aggravating if your trying to use a sporty road bike for more practical purposes. I tried putting 27 1 1/4 Pasela TG's on my Motobecane, and just because of the difference between a 27 1/4 specialized tire and a 27 1 1/4 Pasela to go from perfect to rubbing the back of the FD clamp. Forget about a traditional fender for the same reason.

It's my summer commuter for that reasoning alone. Now has 27x1 Pasela TG's. The Cannondale gets the most commuting duty, due to it's excess of racks, longer geometry, fenders, and 700x32 tires (down from the 700x35 that it came with).

My CX bike develops a "death wobble" in the rear wheel when I'm going down hill at around 30 mph. So down hills are no fun on the bike, and down hills with cornering can be just slightly nerve-racking. I ride the brakes and generally avoid situations like that. On the other hand, my road bike handles like a champ. Hair-pin turns going down hill have become the thing I enjoy most of all about cycling since I got that bike. I climb hills just to be able to go down winding sections. A bike that handles well has me feeling safer and enjoying rides more.

Anyway, I've heard that narrow forks and rear triangles allow for better braking. And I've heard that less tire clearance means the frameset deals with harmonics better, avoiding the "death wobble" ... but I've also heard that isn't true.

What could you do with a bike that's more practical than riding it?

I think it's because designers took too long of lunch. Never understood why Cannondales fat boy couldn't take a tire bigger than 25mm or my gfs old 700c CrossRoad can't take a tire bigger than 35mm on the rear.
My old Bottechia road bike could take 28mm tires. Most of my touring was done on Italian racing bikes that had room for 28mm tires.

all i know is that my road bike that can't fit anything bigger than a 23 with a very tight and short wheel base is profoundly more agile than my MTB hybrid that can take anything up to a 2.0.

there are obviously pros and cons for both, but when i'm on the road bike, the high performance agility is fun to take advantage of.

I hate bikes with very tight tire clearences. I wouldn't buy one ever. I don't see any benefits to it other then a fashion statement.

I can see the point in road bikes having less clearance than dedicated touring bikes and certainly much less than mountain bikes. But it seems like many current designs go out of their way to minimize the clearance even when that isn't necessary for a shortened wheelbase and use of short-reach brakes. Having seatstays curve in so they just barely clear 23mm tires adds no functional advantage and just makes the bike less versatile if the owner wants to use it on bumpier roads or wants the extra cushioning of 25 or 28mm tires.

Fairly recently we had a rider show up with a new bike for a club ride and noticed that the rear tire was rubbing slightly. It had the original 23mm tires, but there was well under a mm of clearance to either seatstay. Took us a few minutes of fiddling with the exact positioning of the wheel in the dropouts to find a spot without any rubbing. And that was with a wheel that was properly trued and a pretty narrow tire. Why cut it so close that there isn't margin for any slight lack of trueness of the wheel or use of a tire that happens to be a bit wider than average?

If you're getting a wobble in your rear wheel then 1 of 2 things is wrong:

1) Your rear wheel isn't straight in the dropouts (or the frame/drops aren't straight with the frame alignment)
2) Your bearings aren't properly adjusted (cup/cone) or are worn out really bad (cartridge) and the wheel can get a wobble.

Speed wobbles happen on the front wheel due to geometry issues having to do with rake and trail ratios. Wobbles on the rear shouldn't happen, regardless of geometry. That's why you can have a touring frame with super long chainstays which is just as stable on a mountain descent as a tri-bike with a forward cut-out designed seatpost that makes the effective stay length shorter than the radius of the wheel.

(Someone correct me if I'm wrong about this.)

I guess it depends on what you mean by limited. Most touring and cyclocross bikes can take 32s or 35s + fenders. That's generally adequate for street use. Hybrids have a similar amount a clearance, sometimes more. There are commuter oriented things like flat bar road bikes which may have very limited clearance. I scratch my head at those sometimes too. It might just be laziness. It's cheaper to take an off the shelf frame design and tweak it a little bit for flat bars than to do something completely different.

As for sportier, non-CX road bikes? Of course I'm only speculating but I think part of it has to do with the brakes. It seems that most road bikes with wider tire clearances come with cantis. With those you need cable hangers and canti posts on the frame + fork. Carbon forks are very popular on road bikes these days and I'm sure constructing carbon forks to work with cantis is a more expensive proposition.

Longer reach brakes are an option too put they don't work as well as short reach brakes unless they're made alot stouter which adds to the expense and the weight.

From the manufacturers perspective, they don't expect people to be putting 32mm tires and fenders on race oriented bikes. They well gladly point you in the direction of their touring bikes.

Personally, I'd like to see an aluminum framed touring/CX bike that could take 40mm tires + fenders for winter use. But I'm a pretty small market.

Bent rim or badly out of round (vertical hop) wheel or wheel+tire combination can cause this too. But I'd bet on wheel not square in drop outs as most likely.

Yes, lower Q-factors, larger chainrings, increase in aerodynamics... you should have asked in frame building forum.