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aluminum stem slipping on carbon steerer tube(7 posts)

aluminum stem slipping on carbon steerer tubeJS Haiku Shop
May 19, 2003 5:59 AM
J2 has a new (to him) Coppi with CF fork & CF steerer. he's using a Cinelli Alter stem (AL), and it's slipping during sprints and efforts. he's got the bolts cranked down pretty tight.



re: aluminum stem slipping on carbon steerer tubeabicirider
May 19, 2003 6:17 AM
Couple of things you may want to check J:
(1) Make Sure there is no grease on fork steerer tube especially if the fork has been recently installed coming up thru headtube may have picked up some grease.
(2) I believe the alter stem only came in 1" not 1 1/8" so you shouldn't need any shim.
(3) try locktite on stem binder bolts.
(4) Think about this first but may want to try to rough up the steerer tube or inside of stem with some fine wetndry fine corase sandpaper like 400 grit or so.
Hope this helps J
Could look this coming weekend on your 600k
Be Safe Out On The Roads!!!!!!!!!
Ray Still
Mooresville, NC
thanks!!!JS Haiku Shop
May 19, 2003 6:37 AM
will advise J2. we considered roughing his steerer tube a bit with fine sandpaper, but didn't know what this would do to CF.

re: 600k, i'm looking forward to being done with all this driving and wind. forecast is pretty nice for southern IL this weekend, tho. :) !
How tight is tight?Nessism
May 19, 2003 6:33 AM
I was having this same problem with my stem until I torqued it down using a torque wrench. The torque spec was quite a bit tighter than my intuition suggested.

Just a thought.

How tight is tight?JS Haiku Shop
May 19, 2003 6:41 AM
not sure if he's using a torque wrench, but he's ham-fisted like i am, and has broken a few parts in the past. i'd guess he has it cinched down really really well and backed off only due to fear of stripping bolts or breaking something.

he has a garage full of bikes, and hasn't had this problem on any other builds. he's also been riding nonstop since he was a young 'un. i think this is his second or third CF steerer, the first being on an older kestrel.

will suggest torque wrench if he's not using one. we share tools, and it would be nice to have a TW in the collective.


expanding plug tight???C-40
May 19, 2003 6:53 AM
There are a lot of different designs of expanding plugs. Some work better than others. Be sure that the plug is tightly expanded against the inside of the steering tube.

The expanding plug on my Colnago fork loosened up a bit and caused some creaking, but never any slippage.

Also check that there is still a gap where the steering clamp is split. Frequent overtightening may have damaged the stem.

If the clamp bolt holes are not threaded all the way through, be sure that the bolts are not too long and bottoming-out rather than tightening. A bottomed-out bolt is real easy to break.
I had same is what I foundspookyload
May 19, 2003 7:15 AM
The topcap was made poorly and the bottom side inner circle would contact the stem before the stem was tight enough. What I have to do is tighten the topcap for preload, then tighten the bottom stem bolt to hold the preload, then take the top cap off, tighten both the stem bolts to spec, then put the top cap back on. I found this was my problem because when I would try to take the topcap off after tightening the stem, it wouldn't come out until I loosened the top stem bolt.