Stem Sizing and Fitting
 

What is the general method you guys use to determine what size stem to use? I'm going to order a thomson to match my seatpost, and I want to atleast be in the ballpark. With my saddle currently set up to be comfortable, when I'm standing I feelt like I'm over the front wheel. I can tell I need a longer stem, and just want to see how much longer. I have heard things for road bikes like," When you are in the drops, your bars should eclipse the hub." Any general rule like that for riding on the track?

Gratzi

http://www.rideyourbike.com/images/salsastem.jpg

or trial and error

Before you get the Thomson, right now Nashbar has some really cheap threadless stems ($9.99). I'd try a few of those first.

I generally go with being on the hoods and and having the bars eclipss the hub. My stem would have to be stupid long for that to happen on the drops.

Also, before you mess with your stem length, make sure that your saddle is where it is supposed to be in relation to your pedals/cranks/bottom bracket.

I just got a longer stem for my road bike. I went from a 100mm to a 120mm. What I learned was that I need a 110mm. Fortunately, I only paid $15 for the stem.

90 if the bikes too big for me. 110 if its too small.

How do you ensure your saddle is in the correct position in relation to the cranks?

Ride it. If you don't have any knee pain after a good amount of riding, it's good.

because im bored at work, just got this in the mail, feel like gloating, and this is a thread about stems...

i got this today...

http://static.flickr.com/76/175635312_0cae40ff1b_o.jpg

<insert evil laugh here>

:D

anyway yea. back to stem sizing.

A rule of thumb that I learned was to sit on the bike in a normal, comfortable position with hands on the bars. Then look down at your front hub. The proper stem will place the handlebars right in the line of sight to the bolts of your front hub.

If the bars are ahead of the bolts, the stem is too long. If the bars are behind the bolts, then the stem is too short.

This isn't an exact science, but it is a good starting point.

Remember, you can also adjust your seat rails on the post to go up and back as well.

as a general roadie fit, you're supposed to have about 25-30 deg of bend in your legs when at the bottom of the pedal stroke, when your cranks are at noon and 6 o clock. most roadies i know ride their seat waaaaayyyy too high - track messengers are probbaly the worst offenders as seat height often seems an estimate based on aesthetics, not pedaling efficiency at all.


with seat rail position, make your own plumb out of something metal and pointy. your pedal axle should line up horizontally below your knee when at 3 and 9:00. most trackies like to have their knee 1 cm more forward for more power.


as for stem length, i think fit is kind of a weird thing when it comes to track-city riding.

based on general fit guidelines, the whole bar-top hiding the hub thing is a general rule, but is largely dependent on how flexible your lower back is, and as long as your within the "normal" 50cm-59cm frame size. plus, this rule is based on a fit with the majority of riding done on the hoods, which don't exist on track bikes.

I'm a big fan of a way longer stem 4 risers, a tiny bit longer than normal for drop bars , and an ultra short one for bullhorns. i played around with my fit alot, but putting ,my track bike on a magtrainer and seeing what positions i could hold comfortably for 15-20 min efforts. sounds nerdy sure, but i was able to get a realistic feel for what's the good compromise for a good efficient fit and one that's good for trackstanding, back-circles and skidding.

anyway, flame on.

d

According to Bicycling Science, adding 10% more height to one's properly measured seat height allows one to generate extra power, while reducing the seat height by 10% or more reduces power output. They can't seem to explain why leg muscles that are tasked to doing the same kind of work would have such differences simply due to seat height.

Maybe because when you look cooler, you go faster:)

Edit double post.

So this will go on a "just right" Italian bike to be named later?

They aren't effin' doing the same work. Muscles have their sweet spot of extension where they can put in the most power. That better match with the power stroke of the crank revolution. Just do three squats and you'll see.

If you add 10% to your properly measured saddle height, your feet won't reach the pedal at all, so that's bull****. And anyway, "properly measured" means "ideal". If you change from that in either direction, you're kicking yourself in the arse.

the stan miles is getting a bit of an overhaul.

spud, was ist das ^

25-30 degrees (i'm sure you meant 150-155 degrees) seems a little too bent. to each his own, but i know that much bend will make my knees hurt like hell.

You're right, I recalled incorrectly, it's not 10% of properly measured saddle height but 10% of leg length for saddle height. Saddle height being the distance from the pedal spindle at its lowest point to the top of the saddle. 100 subjects were tested and maximum sprinting power output was achieved with this setting. But caveat emptor, cadence was not optimized in those tests which were done by Hamley and Thomas in 1967 on a Muller ergometer.

Also more tests results, setting the saddle height 40 - 50 mm above the "normal" height, "normal" being that for which the heel can just reach the pedal with the leg stretched and the posture upright. For durations less than half an hour (a 39 yr old and not very athletic test subject) at least 1 and a half times greater endurance was achieved at each power level.

Conversely when the saddle is set 100mm lower than normal, resulted in a dramatic 15-30% reduction in power.