Bicycle Mechanics - stem position and compression plug

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coasting
12-24-08, 06:37 PM
Hi

I would like to try out different stem positions before I cut the carbon steerer. The steerer is very long and is therefore much taller than where the stem is to be clamped to it.

I have read that the clamp position should be where the compression plug inside is located to avoid crushing the steerer, but since the steerer is so tall how can I try a lower stem position without clamping it lower than the plug? Is it safe to clamp it below the plug?

Should I just cut the steerer shorter and just give myself a smaller range of stem height to experiment with and then cut it again when I know how low the stem should be?

Thanks in advance.


HillRider
12-24-08, 06:44 PM
As long as you don't tighten the stem clamps absurdly tight, the stem shouldn't harm the steerer even if the compression plug isn't aligned with it. You will need a lot of spacers above the stem if the steerer is way too long to allow you to adjust the headset play.

coasting
12-24-08, 07:01 PM
As long as you don't tighten the stem clamps absurdly tight, the stem shouldn't harm the steerer even if the compression plug isn't aligned with it. You will need a lot of spacers above the stem if the steerer is way too long to allow you to adjust the headset play.

Thanks for the quick reply. I'm glad I can clamp below the plug. It won't be for long, maybe 2 or 3 rides should be enough to see how comfortable or not the stem position feels. I do have a whole bunch of spacers to be placed above the stem and it looks ridiculous but as long as it is safe I don't mind.

People don't normally cut the steerer until they have tried and feel comfortable with handlebar height, so do they also ride with a ridiculous pole above the stem for a while?


HillRider
12-24-08, 08:22 PM
People don't normally cut the steerer until they have tried and feel comfortable with handlebar height, so do they also ride with a ridiculous pole above the stem for a while?
Usually you have at least some idea of how high the bars should be, often based on a previous bike so you don't have to leave the steerer awkwardly long.

I've always used my other bikes as a starting point but left the steerer a couple of inches (say 50 mm) higher than I think I will need. A few rides with the stem at various levels firms up the "correct height" and I again cut the steerer a bit long, say 20 mm. Some more riding refines the position and I make the final cut.

However, I always final-cut my steerers long enough that I need a 10 mm spacer ABOVE the stem to get the correct gap for the headset adjustment. That serves two purposes:

1) it assures the stem clamp is completely supported by the steerer tube so there is less chance of damage to the steerer. This is particularly important with carbon steerers.

2) I still have some room to raise the stem if I want to do so later. I could add 5 or 8 mm more spacers under the stem and still satisfy item 1.