Sunday, December 22, 2013

Warped brake clamp marring my handlebar

Swapping a handlebar and stem on an old bike created a small problem with a bent brake clamp.  The bike is outfitted with the original Dura Ace component group.  Unlike a modern brake lever clamp, a screw connected to the clamp is tightened with a nut directed away from the handlebar.

Screw threads go through red hole in brake lever.
Notice that the clamp is stretched towards the threads.

Nut tightens the screw on the far side of red hole. 
The unfortunate effect of the clamp warping is that installing the brake lever mars the handlebars.  The clamp tears even a thin protective surface like painters tape.  Soon it becomes impossible to turn the clamp any further.

An attempt to protect the handlebar with some painters tape.

Just a small turn demonstrates the relative
size of the clamp to the 23.8 mm handlebar.  

The marring from an earlier attempt.
At the moment, I think that there are three options:

  1. Just insert the clamp as is scratching the handlebar along the way.  Afterward, it will be wrapped in handlebar tape thereby hiding the scratches.
  2. Use another set of brake levers.  However, I'd strongly prefer keeping the entire group together.
  3. Find replacement brake clamps.
Option #3 is the most attractive option but finding an effective clamp for a 35-year-old brake lever might be a little tricky.  I happen to have a modern set of Shimano STI levers and Shimano 600 brake levers at the moment.  The brake clamp from the STI levers are clearly too wide.  The Shimano 600 clamp looks like a decent fit although the beveling for the clamp on the inside of the two levers are noticeably different.  I imagine that mating the two would warp the Shimano 600 clamp and I'd like to avoid damaging the original clamp.

Loose Screws and Nuts -- at least until they sell all of their stock and close -- has some replacement Shimano and Dia Compe clamps.  Anyone know a good fit for the classic Shimano brake lever?  Alternatively, is there another strategy for using the old clamps that avoids marring the handlebars?    


  1. I had the same problem recently. The solution, recommended by someone on CR was to use a pair of pliers in reverse to reshape the clamp. Worked like a charm for me. Park also used to make a tool specifically for this task.

  2. Yes, you omitted option #4 - reshape the clamp so it works again.

  3. They make a tool for spreading/reshaping