apparently i should take note of this part :
1 1/8" semi-ntegrated Ritchey OE Logic Zero
now at this site which Stem would you suggest me ? (i need a RED stem between 8 and 10 cm long) (red cos i got a red handlebar) http://www.wiggle.co.uk/stems/
from another forum i found this information :
=============== Fitting a stem is fairly straight forward if you know what you are doing. There are a few potential pitfalls.
Assuming it follows the Ahead standard and is not a quill stem....
1) Steerer diameter (the tube attached to the fork) is usually either 1" or 1.125" (the latter is more common nowadays)
2) Bar clamp diameter MUST match with the diameter of the bar midsection. The most common sizes are the ISO standard 25.4mm (1"), the Italian 26mm or the newer "oversize" 31.7/31.8mm (1.25") but there are others. You might think that 25.4 and 26mm are close, but they are not close enough to use the same clamp.
Both these dimensions MUST be known before you choose a stem.
3) Stem length must be matched to the position in which you can ride. This is not necessarily the position in which you want to ride. If you don't have a feel for this then you are best off going to a bike shop or someone who knows how you should sit on the bike to get help. No one on this forum can help you with this because we can't see you. You are right in assuming that longer means more stretched out.
4) When installing a stem, the top bolt must be tightened first (only tight enough to ensure the headset is not allowed to move), THEN the clamping bolts can be tightened around the steerer.
with the Stem i have, which informations are the ones i need to get another one ? ( i know the 31.8 part and the stem length, what about the 'steerer' ?
or shall i go to the bike shop and ask for help ?
i know there will be limited stems choice and expensive job.
Gary Fisher Big Sur, Santa Cruz Blur, Raleigh Competition, Focus Arriba, Focus Izalco Ergoride
You can measure your for steerer tube with a ruler, but I would bet a ham sandwich (with cheese and mustard) that it's a 1 1/8. Other sizes are FAR less common except some oversized steerers on high-end MTBs, etc.
Seriously, though.. just use a ruler to confirm.
Then, knock yourself out looking for the size and color you want online. At any given time there are thousands of stems on eBay.
1. Yes, it's a 1-1/8" steerer. Most bikes use this standard. Wide choice of stems.
2. There's a huge difference between an 8cm stem and a 10cm stem. If one fits, the other will probably hurt. Don't guess.
3. You need to consider the rise angle as well. There's a very noticeable difference between a 6 degree rise 8cm stem and a 10 degree rise 8cm stem. One, the will be different effective lengths. Two, they will offer different ranges of fit. Again, know what you need. Many stems have their lengths and rise angles imprinted on them in a discreet or less than obvious location. Have you checked?
4. The guidelines in your first post are fine, but they leave out another matter of consideration: Stack height. This is the distance the stem occupies on the steerer tube, and it varies between mfrs. I've personally had stems with 35, 37 & 40mm stack heights; there are pprobably more than that. If your replacement stem has a different stack height than your original, you'll likely need to change out spacers or add some thin 1mm or 0.5mm shims. Otherwise, you may not be able to preload your headset properly.
5. Color is secondary.
6. Your source where you obtained your current broken stem should be a good source for the replacement.
You need a bit of space between the top of the steerer tube and the top of the stem in order to preload the headset bearings. The amount of space varies somewhat to opinion, but 3-6mm is a workable range.
But, you don't want too much space! Too much space could result in excess compression of the stem around the end of the steerer tube as well as less interface.
A general guideline would be to manage your "stack" so that the upper edge of the stem's upper pinch bolt is at or below the top edge of the steerer tube when the stack is under compression. To check yours, you can:
1. Adjust your headset as is. Preload the bearings and tighten the pinch bolts. The headset components are now under compression.
2. Loosen and remove the cap only.
3. View the space between steerer and stem top. View the location of the upper pinch bolt in relation to top edge of steerer.
I'm not there, so can't comment on "safety" of your proposal.