2

On a roadbike, I want to mount dynamo front light on the brake pivot bolt bracket (because my handlebar is occupied with gadgets, and because I want to use the handlebar bag which obstructs the light). Naturally, there is no extra length in the bolt, and the standard solution is a longer recessed nut.

Unfortunately this does not work with my fork: the nut does not go down further than the designed one (I realized this having bought a longer recessed nut after asking a related question earlier).

The only solution I see is a longer pivot bolt. Is such thing available? Or is there any other way to mount the light above the wheel, below the handlebar bag? (I do not want to put the light any lower.)

The brake is Sram Force 2012 (if that matters). I'm ready to replace the brake if another model allows for a solution.

7
  • 1
    There are some different avenues to go down here, but we need to know what sort of brake it is. Also knowing what kind of light it is could be helpful. Dec 1 '17 at 22:13
  • 2
    @NathanKnutson: The mention of recessed nut means it is most probably a modern road rim caliper brake. Dec 2 '17 at 2:07
  • You mention that the new longer nut does not go further into the fork than the original one. This means the hole in the fork crown is not large enough diameter at some point. The fork crown is almost certainly hollow, so it's unclear what the longer nut is hitting. Can you clarify, or post pics? Dec 2 '17 at 2:10
  • @NathanKnutson Standard caliper road brake. I have Sram Force, but I believe that does not make a difference (also I'm ready to replace the brake if another model gives a way to a solution). The light would be again a standard dynamo light such as one from Busch&Muller. I have updated the post accordingly to your comment. Dec 2 '17 at 8:31
  • @JohnZwinck The fork is carbon monocoque. It has no openings besides the front and rear entries for the pivot bolt. Picture of that would be probably useless - just black smooth carbon :-/ Dec 2 '17 at 8:32
5

Some caliper rim brakes do have interchangeable pivot bolts and accompanying hardware available, either explicitly or by way of what are usually simple hacks. Within Tektro brakes for example, many of the brake arms use the same bolt style and hardware and can be switched between front recessed, rear recessed, front external nut, and rear external nut mounting if you have the hardware to swap around, which can be useful at times in the shop when you need a certain color, reach, front/rear position, and nut style permutation right now. Tektro makes a product that supports this so you don't have to go cannibalizing other brakes. But none of that applies in any way to a Force brake, or if there were a way of getting another company's external nutted pivot hardware on there (which would be one way of solving this, probably) it would be an experiment and a more fabrication-requiring hack. Your brakes don't have any pivot hardware offered aftermarket by SRAM.

If you're willing to change the brake, you may be able to get a front brake intended for external nut mounting to work. I say may because you'll probably need to trim the bolt some to work with your recessed nut, but they only give you so much threaded length to work with, so you'll need to have enough threads falling in the right area. I believe all or almost all brakes have threads that can't be extended with a die because the material isn't there to do so, either because the threads are rolled or some other reason. Another potential solution if that becomes a stumbling block would be putting in some spacers in the recessed part of the fork and just using an external nut.

Another approach is using one of the generator light brackets available that are somewhat intended to address issues like this by only adding a bare minimum of material behind the caliper. (Maybe you've already looked at this; I offer it in case you're running into the issue by trying to use one of the chunkier generator light brackets out there, such as the plastic ones.) An example would be the B&M 471F:

enter image description here

Many people who ride road bikes with handlebar bags, such as randonneurs, use handlebar bag racks and other front racks with integrated light mounting for generator lights.

1
  • Thank you for confirming that the SRAM bolt cannot be easily replaced, and for the Tektro link; my next attempt, if any, probably would be a Tektro brake. B&M 471F would not work, as it has side folds protruding ahead which would hit the brake arm. Happily accepting the answer. Dec 2 '17 at 11:17

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.