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-   -   Do 31.8 clamp bands for brake levers exist? (https://www.bikeforums.net/bicycle-mechanics/1137510-do-31-8-clamp-bands-brake-levers-exist.html)

Celeste Mike 03-05-18 04:10 PM

Do 31.8 clamp bands for brake levers exist?
 
https://www.universalcycles.com/imag...rge/218449.jpg

I'm talking about the type of clamp band on the left in the above photo. This part would be easy to swap out, but I can't find any evidence of them existing in 31.8. The reason being I'm wondering if there's a way I could put Guidonnet brake levers on carbon bullhorns. :foo:

These levers: GearInches.com Guidonnet
on these bullhorns: https://www.aliexpress.com/item/Fixe...810471849.html

I know it's unconventional but surely I'm not the first person to wanna put weird brakes on a thick bar. Any help or suggestions is much appreciated.

CliffordK 03-05-18 04:35 PM

:foo:

I've seen 31.8 interrupter brakes, but I don't think they're band mounted. The mounts are usually cast aluminum.

One could probably make a custom mounting strap with a bit of tinkering in the workshop. You will have to be able to open the strap enough to get it past your aero wings on the bars.

FBinNY 03-05-18 04:47 PM

There's no reason for anyone to make 31.8 clamps for most levers. While the bar is nominally 31.8mm, that's only in the stem clamp area, and it will step down to the standard 23.8mm (15/16") OD for the working length.

You might conceivably need 31.8 clamps for anything clamped immediately on either side of the stem, like computers, but brake levers aren't mounted there.

Of course, some interrupter levers may need the larger clamp if the bar doesn't step down close to the stem.

Celeste Mike 03-05-18 04:54 PM


Originally Posted by CliffordK (Post 20206611)
:foo:

I've seen 31.8 interrupter brakes, but I don't think they're band mounted. The mounts are usually cast aluminum. One could probably make a custom mounting strap with a bit of tinkering in the workshop.

Yeah, I could put interrupters, but I'm really interested in trying these guidonnet levers. Hence the band search. I was thinking it might have to be custom made, which I'm sure someone could do easily, but unfortunately I don't have the tools for it myself.


Originally Posted by CliffordK (Post 20206611)
You will have to be able to open the strap enough to get it past your aero wings on the bars.

Oh crap, I forgot about that part! *facepalm*

Celeste Mike 03-05-18 05:03 PM


Originally Posted by FBinNY (Post 20206631)
There's no reason for anyone to make 31.8 clamps for most levers. While the bar is nominally 31.8mm, that's only in the stem clamp area, and it will step down to the standard 23.8mm (15/16") OD for the working length.

I hear you, but this particular bar doesn't step down:
http://ae01.alicdn.com/kf/HTB1c8XMlz...bq6zbEXXad.jpg

Although @CliffordK's point about getting past the aero wings presents another problem. :/

CliffordK 03-05-18 05:56 PM

That second bar that you show looks like the "wings" may be removable, or a separate part from the main bars.

Nonetheless, you should be able to pry the clamps open... hopefully. If you found, or had some made that were the right size.

I haven't tried the Dia Compe 139 brakes. They'd have to be a pretty good match for your bars to be useful, although you should have some right/left adjustment and rotational adjustment during the install.

FBinNY 03-05-18 06:01 PM


Originally Posted by CliffordK (Post 20206768)
That second bar that you show looks like the "wings" may be removable, or a separate part from the main bars.

Nonetheless, you should be able to pry the clamps open... hopefully. If you found, or had some made that were the right size.

I haven't tried the Dia Compe 139 brakes. They'd have to be a pretty good match for your bars to be useful, although you should have some right/left adjustment and rotational adjustment during the install.

Yes, the OP can pry the clamps open but that won't solve the problem. They will only work on a bar that's roughly 23.8mm because the band isn't long enough to close and bring the holes into alignment on anything larger.

It's possible that some brand of interrupter lever has an optional 31.8 clamp, but I suspect that the OP's only option is going to be DIY.

tyrion 03-05-18 06:59 PM

Have custom mades ones made out of 3D printed titanium.

Cross Creek 03-05-18 09:12 PM

I use Dia Compe DC135 levers quite often for city and single speed builds. 22.2 and 23.8 clamps are readily available, not always cheaply in the case of the 23.8's. I've mulled over the idea of making sockets tapped for the brake draw bolts that could be glued with high-strength epoxy to the bars. In other words, getting rid of the clamps altogether. The two "hard" spots would be making sure that you put them in exactly the right spot, and making sure that the glue joint is solid and reliable. Brazing the fittings to the bars is another option, but the danger there would be softening/weakening heat-treated bars.

CliffordK 03-05-18 09:43 PM


Originally Posted by Cross Creek (Post 20207128)
I use Dia Compe DC135 levers quite often for city and single speed builds. 22.2 and 23.8 clamps are readily available, not always cheaply in the case of the 23.8's. I've mulled over the idea of making sockets tapped for the brake draw bolts that could be glued with high-strength epoxy to the bars. In other words, getting rid of the clamps altogether. The two "hard" spots would be making sure that you put them in exactly the right spot, and making sure that the glue joint is solid and reliable. Brazing the fittings to the bars is another option, but the danger there would be softening/weakening heat-treated bars.

Interesting concept.

One wouldn't necessarily need to use short bolts. So, one could potentially drill the bars for through bolts.

I'd still want to spread the forces out a bit so some kind of a band would be nice, but one could potentially use a local build-up of carbon fiber as well as a complete wrap, then drill and use a through bolt.

In theory, the bolt could also be fed from the inside of the bars, and thus one would only have to half drill the bars.

Of course, I'd hate to get my brake levers wrong, and have them incapable of doing an emergency stop.


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