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How to clamp a brifter to the bar more securely if the clamp is already very tight?

More detail: After a small crash (no scratches on me, just a few on the bike), one Shimano Ultegra brifter was wobbling relative to the handlebar. I tightened the clamp bolt that attaches the brifter to the bar as much as I could, but the brifter was still wobbling. I undid the clamp, removing the brifter from the bar and saw that the clamp is a bit rusty, but looks intact. Retightened the clamp bolt as much as I could (the hex key broke), but the brifter is still wobbling on the bar. Before the crash, neither brifter wobbled.

There is no bar tape or anything stuck under the clamp or brifter edge, I checked before retightening.

The Shimano dealer manual does not give additional info besides tightening the clamp bolt (http://si.shimano.com/pdfs/dm/DM-ST0002-05-ENG.pdf).

Clamp bolt recess Clamp on bar from the inside Clamp on bar from the outside

  • Can you post a photo of clamp recess (the place shifter lies on bar) and the hex nut recess? – Klaster_1 May 26 '18 at 5:37
  • That is a lot of corrosion, and while its unlikely to be the cause of your loose brifter, it might be a good time to strip off all the bar tape, clean and closely inspect, then if it seems solid still apply rust remover/fixer, optionally paint, and then reassemble with new bartape (I bet your old bartape is salty) – Criggie May 26 '18 at 8:15
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    Disassembling (ie removing everything from the bar, including your brifters) will let you inspect the brifter mount from the underside. I wonder if the bolt is stretched, or if the clamp is slightly stripped in the thread. Shimms may help, but they also may not help. – Criggie May 26 '18 at 8:16
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    Use a shim. Metal from a beer can works pretty well. – Daniel R Hicks May 26 '18 at 11:42
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    @Criggie The handlebar is aluminium, so the red rust must be coming from somewhere else, e.g. clamp. Aluminium oxide is a white powder, which I had on a different spot on the handlebars. – Sander Heinsalu May 26 '18 at 23:20
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First thing to do is loosen the bolt all the way and grease the threads. If possible, snake a lube dripper in and get a drop of lube under the bolt shoulder too. That may completely fix it, but while you have the lever separate from the clamp, look everywhere you can see for cracks in the lever body that might be preventing the clamp from snugging everything up properly. Pull back the hood as needed to inspect. If none of that leads to an answer, next thing to do would be get better eyes on the section of bar it's trying to clamp, and also the clamp itself.

Given this started with a crash I'd be pretty worried that the lever body is broken somewhere.

  • Oiling the bolt did not help. Retightening, the brifter is slightly looser, but I did not use unreasonable force this time. There seemed to be no cracks, but I cannot see inside the brifter of course. Shims cut from an aluminium can under the clamp may help tighten it. – Sander Heinsalu May 26 '18 at 7:30
  • You can peel the rubber hood covering the mechanism to the front and even remove it completely. It will give an excellent view on the body. – Carel May 26 '18 at 12:55
  • @Carel There is only black plastic under the rubber hood, as can be seen from the photos. Part of the mech can be seen by pulling the brake lever, part by pushing the shifter lever to the side. Nothing is visible from the clamp side. – Sander Heinsalu May 26 '18 at 23:46
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Two shims of double drink can thickness, one to the right of the clamp bolt and one to the left, solved the problem.

I speculate that the clamp had somehow bent or stretched slightly in the crash, so the bolt did not pull it strongly enough any more. Shims increase the pull, so the clamp is secure on the handlebar again.

Of course, future crashes may dislodge the shims and cause other problems with the brifters.

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