Please post a photo when you have it produced.
So here it is: we now have the first broken frame caused by the UCM Caliper:
http://unicyclist.com/forums/showthread.php?p=1662619#post1662619
I think this belongs to this thread but was not mentioned here yet:
To avoid broken d’Brakes, Hugo from the german part of the forum designed a strut to support it. We call it “Hugo Strut”. Many riders have installed one to their d’Brake yet. It also helps against vibration noise
This is how it looks like:
I’d like to figure out something like that for my Oracle frame, which doesn’t have the magura mount to use as an attachment point for the strut. The stock brake worked fine, but I had to replace it after a crash, and I’ve had a terrible time trying to make the new brake stop shuddering.
I’ve tried things like cleaning, sanding, replacing pads, replacing rotor, no help. I finally stopped it by forcing a little bit of toe-in on the pads, but I don’t like the solution, so I’d love to find something better. Has anybody tried something similar to this, but just clamping it to the frame leg somehow?
Yes. A strip of flat steel, a m6 bolt and nut, and some aluminum tube (I believe I used 9mm diameter) will do the trick nicely.
Bend the steel around the frame leg, drill 2 holes through it. Hammer one side of the tube, drill a hole large enough for the bolt on the brake mount to pass through. Shorten to desired length drill another hole through the tube for the frame clamps screw to go through. I used a different pickup on the D brake than the one Eric posted (the one where the post mount adapter is bolted to the bearing holder) I can dig out pictures if you want.
It really helps a lot, much less vibration under braking now.
Thanks for the replies - I’ll give it a try.
and this is, how the solution looks like on an Oregon:
http://unicyclist.com/forums/showpost.php?p=1641531&postcount=28
Here’s my first pass at a fix, just using things I had lying around; I haven’t had a chance to really try it out yet.
Got a large vibration when doing steep downhill today. Checked this thread out and made a heath robinson fix.
I used an old cateye light clamp and a bit of metal from an old b**e rack.
Seems to work on light braking - test in anger later.
Stewart
Posted elsewhere already, but… another one for the collection. Improved braking massively on my 36er.
Is there any connection between the tube and the brake adapter (thread in the tube?)? Or didn’t you attach both parts to another because the brake force will always push the adapter onto the tube?
The bolt is extra long, and protrudes about 8mm beyond the adapter. There’s a piece of 8mm diameter aluminium rod about 12mm long which is drilled and tapped and tightened onto the protruding bolt. The strut tube has an ID of 8mm so it fits tightly over the stub. The tubing is bent very slightly to line up the bolt and hole in the frame.
So to answer the question, it is quite securely aligned but is strong in compression only.
Secure Rod
Hello lightbulbjim, I like your torque arm ! , how would this action be effected if you drilled and pinned the 8mm x 12mm rod (internal) to the outer tube ? Would the ability to no longer expand cause any vibrations ?
MarkI don’t think so. Because all the others I’ve seen so far, including mine, have no ability to expand and all help against vibrations.
I’ve put a thin layer of rubber between every part (frame - d’brake, brake-adapter - hugo-strut, hugo-strut - frame) but I don’t thik it was necessary. Hugo (who built the first of theese) used no rubber at all and was able to eliminate all vibration of his brake with this strut. I’ve also put a bit of pre-load on mine in hope that it might support the d’brake even better.
Maybe, but disassembly would be harder and I would have to be careful when tightening the assembly onto the bolt to ensure it ended up in the same position. Having two separate pieces makes this a bit simpler.
The vibration is pretty much under control. There’s a small amount of squeal with light braking pressure but once it loads up it’s silent.
I’m happy with this for now. The next improvement will be to weld a bracket to the frame, but I have a bunch of house projects which I need to finish before I can play :).
Just tested down steep hills - no vibration.
It seems that more people should be suffering with this problem??
Pretty sure a lot of people are suffering but don’t realise what the issue is or that there’s a solution.
I’ve recently hacked together a quick and dirty one for my old KH29er with stuff I had lying around as the vibration made using it as a freewheel basically impossible, and I know at least two people with oracle 36ers facing the same issue.
The steel has since cracked at the brake end as really I need to join it to the d’brake mount (to avoid stresses on a bend) as Hugo initially did, but this quick fix worked for three rides to test the concept.
