Bicycle Mechanics - How to properly install a stem expander for carbon steerer forks?
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01-06-08, 02:22 AM
Can anyone help me? Thanks!
01-06-08, 07:42 AM
What do you mean by "stem expander"?
Do you mean the compression plug that adjusts the headset? They come with directions.
Do you mean the stem clamp that tightens a threadless stem onto the steerer tube? They usually have a torque spec engraved on them or in the direction sheet. Usually the torque spec is 8 N-m but you want to use less for a carbon steerer. Generally just tight enough to prevent it from slipping.
If you mean the expander wedge that holds a quill stem inside the steerer of a threaded fork then the answer is simple; you DON'T EVER use one.
01-06-08, 11:37 PM
Its this one I am looking at using in my carbon steerer fork.
01-07-08, 07:57 AM
It should come with installation instructions. If not, here is the usual procedure for that type of expander.
Install the headset and fork with the steerer cut to the proper length. Place the stem and any spacers you need over the steerer but leave the stem's clamp bolts loose. Place the expander plug in the top of the steerer tube being sure there is 2-3 mm of either the stem or a spacer above the top of the steerer. Tighten the top bolt on the expander to make it grip the inside of the steerer tube and compress the headset until all of the play is gone. When the headset is adjusted properly, align the stem and tighten the stem clamp bolts. Do not over tighten them as I mentioned above.
01-07-08, 01:16 PM
Generally, what HillRider mentioned is the general way of doing it. However, from personal experience (I have used at least 4 different brands or makes of expanders), it isn't always that simple. Most of them are similar but different enough to create problems and they usually don't come instructions. I have used the same one you linked. It has a "top cap" that goes over an "inner cap". There is a bolt that goes into another bolt. You tighten the inner cap before tightening the top cap. If you overtighten the top cap, the bolts can get stuck and you can't get the inner one out.
I found this expander to only work well on some forks. If you want a better solution, go with the FSA expander. That is the best one I've come across.
01-07-08, 04:52 PM
Do you know where I can get the FSA Expander?
01-07-08, 06:16 PM
I have used the same one you linked. It has a "top cap" that goes over an "inner cap". There is a bolt that goes into another bolt. You tighten the inner cap before tightening the top cap. If you overtighten the top cap, the bolts can get stuck and you can't get the inner one out.
I wasn't sure from the picture but it looked like the Profile-type expander plug which is a one piece unit. You stick it into the steerer tube and the top bolt both tightens the plug in place and adjusts the headset. Hence my directions. If it is a "two piece" expander, i.e., you tighten the plug in the steerer first then add the top cap and bolt to adjust the headset, my directions are misleading
If you want a better solution, go with the FSA expander. That is the best one I've come across.
+1 I've had very good luck with the FSA expander in two carbon forks.
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