Riding a cross bike a size too small

[FastforaSlowGuy]

Wanna try some CX this year. Don't wanna spring for another bike (wife would kill me). Said wife does, however own a CX bike that is a size too small. With a longish stem, I can make it work. Stem would be 110, maybe 120, which is pretty long on a 50cm TT bike.

I imagine this will impact steering some, so thoughts on whether I'd be handicapped on a twisty CX course? And anyone know if someone makes a seatpost with more than 20 mm setback?


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[regularguy412]

Disclaimer: I've never ridden CX.

However, I'd expect that a stem that is proportionally too long for the bike will: A) hang you out over the front so the weight distribution will be 'off' and B) may slow down the handling a bit. You may be able to 'ride' it, but you may not be comfortable on it. 'Comfortable' in this case meaning: confident.

Mike in AR:beer:

[rauce]

Plenty of 25mm setback posts out there, fsa k-force and 3t anything come to mind.

Nothing wrong with 110 or a 120 stem IMO, my co-worker runs a 120mm stem on his 50cm Ridley x-fire. You'll find the steering slows down a little.

[Charles M]

Stop...

Check the geometry on the frame.

If it were properly designed, it will likely have a slack head angle and longish wheelbase that might likely make the added stem size very little issue for you.

It will handle a little short for cross, but if you've not been on a cross bike, you may not find it bad at all.

[11.4]

Most of the weight out front on the bike is arms, not your torso, so weight distribution isn't that much of an issue. And if your weight is a little more on the front wheel, it just means the bike will track a little better and the front won't wander as much. How the bike works depends mostly on how well you can ride it, and you'll have to figure that one out for yourself.

Small bikes do just fine with longer stems. I ride a 50 cm c-c frame and I like the handling better when I get out to a 12 or 13 mm stem. On my single speed cross bike, I actually have a 14 and do fine with it. People make a lot of noise about how steering changes, but honestly, most of your weight is on your saddle, not out over the bars, and you should be turning by heeling the bike, not by turning the bars, so issues like toe overlap and stem length aren't that relevant in my book.

You have the bike. Race it. Learn what works and doesn't, and then next year you'll have a better argument for a new bike if you really feel you need one.

[martinez]

I feel like a cx bike that's a size smaller may even be more fun.
You'd be able to throw the bike around more, which I think is useful for cx.
When I had my nature boy, I had the smallest size even though the 49cm would fit a little better...but I had my share of wild riding by really working that bike!
I miss it sometimes

[sparky33]

You have the bike. Race it. Learn what works and doesn't, and then next year you'll have a better argument for a new bike if you really feel you need one.

Yes^

Just go for it. That/any bike will do fine for your first several races.

[sokyroadie]

And anyone know if someone makes a seatpost with more than 20 mm setback?
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FSA makes a 32mm setback seatpost.

Jeff

[Gummee]

I run 110mm to 120mm stems on everything I ride.

Go for it!

M

[thirdgenbird]

If I do another cross bike, I will shoot for a 130mm stem.

[Nooch]

cannondale's rule of thumb was always to size down on their cx bikes to account for standover and such. Remember, you're supposed to be doing flying re-mounts on this thing, a little extra clearance is never a bad thing :)

[bcroslin]

I run a 120 stem slammed on my CX bike. You'll be fine.

[polyhistoric]

A size smaller is better than a size too big.

you'll just have to watch your positioning that you don't lean too far forward over the axle while going through some rooty technical stuff (otherwise you are primed for a pitch over the bars). Shouldn't be too bad with only 120mm.

Cross is so fun, you'll quickly become addicted.

[11.4]

A size smaller is better than a size too big.

you'll just have to watch your positioning that you don't lean too far forward over the axle while going through some rooty technical stuff (otherwise you are primed for a pitch over the bars). Shouldn't be too bad with only 120mm.

Cross is so fun, you'll quickly become addicted.

Last time I checked, it was my sorry butt that determined where my center of gravity was positioned on the bike, not my hands. Going down a size shouldn't change your seat angle much (and if it did, you'd compensate with saddle positioning and seat post choice), so your butt, like mine, should end up in basically the same position. The only thing about that smaller bike then becomes a longer stem to compensate for a slightly shorter top tube. Now your wheelbase isn't going to start getting smaller yet, at least not significantly, because it has all that clearance and those big wheels to deal with. So again, you're just correcting for a top tube that might be designed shorter to accommodate other riders who really need it. In short (pardon the pun), you're not doing much to your weight distribution, only to where your hands sit.

And as good fitters will tell you, you should be able to take your hands off the bars, in race position, and be stable on the bike (not sitting up, still bent over in your position). Otherwise your hip rotation is off, which throws a lot of pressure onto your hands, which is something you need to correct. This is why pros will ride smaller bikes with long stems. Plus, everyone has gradually come to understand that you don't turn with your bars; you turn with your butt. It's always your butt. Somehow I should be happier about that, butt I'm not.

[tiretrax]

Buy the Serotta 10.77 for her that I have in the classifieds, and you'll be able to get the Moots Psychlo X you're wanting!

[zennmotion]

The center of gravity on a cross bike on a cross course is more noticeable/less forgiving than a road bike IMO. This is especially apparent when pushing through mud and sand- too much weight on the front wheel and the bike will tend to want to plough sideways rather than slice through in a straight line. In other words you'll have difficulty keeping the bike confined to a rut or keeping a straight line and especially as an inexperienced crosser you'll end up dismounting and running some of the marginally rideable sections. That said, roll with whatever you have, it really doesn't matter much in your first few seasons of cyclocross. The races are too short and hard to be thinking much about your bike- when you're struggling to hold down breakfast the last thing you'll be worried about is how long your top tube/stem is.

[zennmotion]

Last time I checked, it was my sorry butt that determined where my center of gravity was positioned on the bike, not my hands. Going down a size shouldn't change your seat angle much (and if it did, you'd compensate with saddle positioning and seat post choice), so your butt, like mine, should end up in basically the same position. The only thing about that smaller bike then becomes a longer stem to compensate for a slightly shorter top tube. Now your wheelbase isn't going to start getting smaller yet, at least not significantly, because it has all that clearance and those big wheels to deal with. So again, you're just correcting for a top tube that might be designed shorter to accommodate other riders who really need it. In short (pardon the pun), you're not doing much to your weight distribution, only to where your hands sit.

And as good fitters will tell you, you should be able to take your hands off the bars, in race position, and be stable on the bike (not sitting up, still bent over in your position). Otherwise your hip rotation is off, which throws a lot of pressure onto your hands, which is something you need to correct. This is why pros will ride smaller bikes with long stems. Plus, everyone has gradually come to understand that you don't turn with your bars; you turn with your butt. It's always your butt. Somehow I should be happier about that, butt I'm not.

This is roadie advice, not cyclocross- it's different. You want to be sitting more upright (harder on a frame that's too small) and you want to be able to unweight your front wheel, also harder on a frame that's too small. Your fore-aft saddle position is important to how a cross bike handles- and long stems are not as common in cross racing as they are on the road. And take a cue from MTB/XC racing where short stems are the norm. But again, don't sweat the equipment when starting to race cross, it all works, check out the motley range in a Cat 4 field, everything from hybrids to carbon pro bikes- and the hybrids get the style points IMO, sometimes they even win races.