therearegoats

Hi,

I recently bought a new road bike in a 52cm frame size, which fits well in terms of standover height (a couple inches, give or take). I'm finding that the top tube for this size is a bit long, though, at 54cm. Right now, I'm using a 90mm stem and finding that I'm still a bit too stretched out in the drops (while the straight part of the bars feel fine...if maybe a bit short). Would it still be acceptable with this size frame to go to an 80mm stem or should I have gone with a smaller frame size to begin with?

Any help would be greatly appreciated!

Robert

rogerstg

You should discuss this with the shop from which you bought it.

dbh

Also, as you ride more frequently, your body will get used to riding bent over. That said, you want to make sure you've got a proper fit.

scirocco

Whether a shorter stem is "acceptable" or not seems to depend on the frame geometry. On some frames shorter stems can make the handling too twitchy, while on others it seems to have no effect.

As to whether you should have gone for the smaller size, bear in mind it will have a shorter head tube, so the bars would have been lower. Is your flexibility good enough that you could have coped with this? If so, then yes, you should probably have gone for the smaller size.

tpelle

I had pretty much the same issue, and today I went to the LBS and picked up a shorter stem that's angled up more. Working great. Now, if I glance down at the front wheel, the handlebars are pretty much in line with the hub. I didn't notice any difference in handling on my ride home, other than I no longer felt like I had too much weight on my hands and my neck and shoulders were no longer stiff.

Personally I prefer a frame that's taller rather than shorter, as long as standover clearance is OK. I hate to have a bunch of seatpost sticking up out of the top of the seat tube.

dmp

Standover height has very little to do with proper fit. The key parameters are top tube size and head tube size. If these are properly fit the standover height will take care of itself. If you need a stem less than 100mm in length you (most likely) have too big a frame (or have unusual dimensions). Sounds to me like you need a better fit. You can get a vague idea of what to start with by using the online fit calculator on the www.competitivecycling.com website, but a fitter with a good eye is best. I would get the numbers from the online calculator and take them back to your shop and ask to see the most experienced bike fitter there. Although any good shop should include at least a rudimentary fit with the sale, it is worth paying for a comprehensive fit if the fitter truly knows what he or she is doing.

ZippyThePinhead

I have a bike which is probably a little too big for me. I bought it used, and it came with a 40mm quill stem. I rode it for 1400 miles, and it worked great. I still have it and ride it occasionally.

I even took the bike to have a professional fitting and the fitter commented that while the short stem was unusual, the combination of short top-tube and short stem worked for me.

therearegoats

@Tpelle: When you test your sight lines to see if the bars are in line with the front hub, you do this when your hands are on the straight part of the bar and not the drop/hoods, right?

@Scirocco: I hadn't thought of how much lower the bars would be w/ the lower seat tube. Good point. I think that would only make the problem worse.

@DMP: The numbers I'm getting through the fit calculator indicate that I'm right in the ballpark, but that the top tube is just a cm or so long. I think I'll try flipping the stem over to see if that helps a bit.

Thanks for everyone's responses.

Robert

clink83

Small frame=more twitchy handling, more bar/seat drop
Larger frame=more stable handling, less bar/seat drop.
As long as you can get the proper knee/pedal relationship with a comftertable reach, frame size isn't as big of a deal as some people make it. 2cm won't kill you.

rat fink

I can't agree with this. Those situations have more to do with weight distribution and comfort than anything.

lazerzxr

Short stems are fine, what reach are your bars? It sounds opposite to what you want but try moving your seat back to re ballance yourself, i used to have a 90 mm stem on my bike until i found that moving my seat back allowed me to be more comfortable all round with a 100 stem.

A short stem will not ruin handling, those that say it will is because they tried a short stem that was too short for them, if handling feels bad then the stem is too short for you not the frame.

8Lives

I'd be careful with that. Seat position is set in relation to the crank, pretty critical to getting your hips in the right place. It is about the last thing I'd try (okay, I wouldn't at all) to get the bars in the right position.

What you really want is a professional fit that gives you your XY coordinates. Once you know where in space feet, hands and hips should be it gets a lot easier to fit the right frame, stem, bars etc.

clink83

No, it has to to deal with wheelbase. The larger your frame is, the longer the radius of the turn is for any given steering/lean angle, and the bike will be more "stable", but a smaller frame will have a shorter wheelbase and feel less stable. This doesn't apply to all bikes though, but it's a decent rule of thumb. It's pretty similar to the turn radius of a ski.

BarracksSi

Well, when I went between two different frame sizes of the same bike, the longer stem on the smaller frame indeed felt more sluggish than a shorter stem on the bigger frame.

I started with a 56 CAAD8, then made the shop swap me onto a bigger one when they decided that to fit me on the 56, I needed a 130-140mm stem and the saddle shoved all the way back. I left with a 60 (they didn't have a 58 on hand), then came back a week later and got a 90mm stem. Definitely twitchier with the shorter stem.

But... it was a weird twitchiness, though. It felt like quick steering turning a big bike. Conversely, the smaller bike/longer stem combo felt like truck-like steering on a small bike. I should've been on a 58 instead anyway.

At that time, I preferred the bigger bike with the short stem. I got used to the twitchiness.

lazerzxr

Sounds like the OP has not had a bike fit, so my post was really to point out that a bike can feel long even when it isnt and that sometimes an unlikely adjustment (which costs nothing) can fix things.

Having said than I also think bike fits are over rated (mostly) and I dont believe in KOPS either, ballance is far more important for overall comfort. I agree the saddle should be set to keep the knees comfortable but there is more than 1 position that will do that and the "right" position is the one that doesnt cause other issues.

My theory is that a lot of pros dont have their knee perfectly over the pedal because every pro bike I have seen has a set back saddle no matter what the riders proportions, and you wont damage your knees from a different position - for example TT bikes sit well in front of the pedal. All this leads me to think that you can set your saddle wherever you are comfortable. My knees are well behind the pedal spindle and I find in that position i can use a longer stem and bend my arms with almost no wieght on my hands. With KOPS all my weight is on my hands and my shoulders hurt while the bike feels too long even with a short stem.

rat fink

I can't agree with this either. There are several other contributors to the fast steering on some bikes as opposed to others.

MichaelW

80mm stem is within the bounds of "normal" size for a smaller frame. I use 80mm on a medium frame and it works perfectly well. On small frames you could probably go down to 60mm with no ill effects. Some people rider even shorter stems.
The "ill effects" are a slight increase is steering sensitivity due to the "tiller" effect of the stem. You get used to riding and forget about it.

The old guide that bars should block your view of the front hub is not very analytical. I happens to work with average riders on average road bikes but that doesn't mean it works for everyone.

UCIMBZ

Pro bike cycling is a different animal. The school of tought is to put you on the samllest possible frame (less weight and flex) and make the adjustments with saddle postion, seatpost setback and height and stem lenght.

UCIMBZ

It is called headtube angle.

urbanknight

I thought the amount of flex in a ski as well as the curvature of the sides affected turning radius as well.

dmp

I'm afraid that neither of you are exactly correct. The stated radius of the ski (e.g., a slalom ski with a 12m radius, vs a big mountain ski with a 20m radius) is a static measurement. If you take the side cut of the ski and extend that arc to a complete circle, the radius of that imaginary circle is the radius of the ski. That would be the arc that the ski would take only if you tipped it on its side in a pure carve. However, the ski can obviously be made to take an arc either deeper or shallower than that "fixed" dimension depending on how much you flex the ski (thus the flex pattern of the ski, as well as the skier's input, comes into play) how much you get on edge, how much you carve vs skid, etc. It is really not analogous to the bike's geometry because the bike is rigid compared to the flexibility of the ski.

The stem length should affect steering because it affects your weight distribution over the front of the bike and is the lever arm for your steering input, but head tube angle, as UCIMBZ points out, is critical.

teterider

Oh boy.

There are lots of frame and part contributors to how a bike handles and the "twitchiness", including stem length, frame size, and wheelbase as mentioned. However, the real factor is the TRAIL. the headtube angle as stated above does not determine trail, but is in the equation along with the fork rake of how it is determined and measured.

There are plenty of websites that will calculate trail and explain it for you so I won't go into detail here.

urbanknight

Huh? I mentioned flax as well. But yeah, it has nothing to do with bicycles, but I do realize that clink's point was to say that shorter means smaller radius, which is a very general rule that can be canceled out by other factors.

therearegoats

Thanks all. This have been really helpful. A guy at my LBS mentioned weight distribution as something to think about in getting a smaller stem, but also seemed to think that 80mm wouldn't be too small.

That said, here's what I did: I tilted my drops up by about an inch. And that totally did it. The part right before the brake hood is about parallel to the ground now, which isn't ideal since it makes the braking angle a bit weird. But it completely changed the feel of the bike---and only because I'm an inch higher. I was going to try flipping the stem (the better option) but realized that I couldn't since my brake cables were too short and it would require un- and reewrapping my bars (which I didn't want to do because I just wrapped them). It's fascinating how the slightest adjustment can completely affect comfort on a bike...

Just for curiosity's sake, when using that old method of sizing (when the bars are supposed to block your view of the front hub), do you measure this when you're in the drops or on the flats?

urbanknight

That's just it. It's not an old or new method. It has always been a rough estimate and not a rule. For that reason, it depends on who you ask, although I have only heard it for the tops or the hoods. Never on the drops.