one way to put V-Brakes on Mag mounts

V-Briake Adaptors

This is a post of mine from a few years ago.

I was the one who originally posted the Mission 4 bolt adaptors. I am happy to see that UDC uk started supplying them. I bought them way before UDC uk was selling them. After using them for about a year and a half now I have the folowing to say about them.

They are big and clumsy and torke is increased. I would not use them on a MUni. I have kept them on my KH29 where I do gentle feathering of the breaks on downhill sections of road. They are perfect here. Also I very rarely fall on the KH29 when doing cross country and road riding.

In MUni they get hit a lot and I have had the post break in the holes. It is then a bitch trying to get it out! I would use Maguras for hard MUni. There is also a 2 bolt adaptor made by Woodman that sells for $50 that would probably be better. However if yuo are going to spend so much money you might as well just get the Magura!

In summation: For cross country or road riding v-brakes with adaptors are fine. For Muni you should stick to the Maggies.

26" wheel in 29" frame

This works just fine, although maybe not the prettiest thing in the world. Same setup as I used in my prior post, but I added an extension to move the location of the v-brake mount. I added a spacer so the brake would clear the little mounting screws.




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that is a really clean set up.
Is your rim cracked?

V-Brake setup has been working well since May… Thank you to those who post how to do these mods!

i just took of v-brakes from an old bike :slight_smile:

What is the function of the aluminium angle…? is it so that there can be a hole for the little metal protrusion to keep the spring under tension while locked against the side of the frame…or… :thinking:

Does this sound like a correct materials list I’ll need?

2x #10-32-1 1/2" screw
2x aluminium angle
2x 1" aluminium tube ~7mm o.d., fit around #10 screw; I have a pen barrel that fits just inside the brake’s hole…but the I.D. is a little big… maybe this’ll work?
4x #10 washers

It looks like you’re on the right track, but the bolts are 4mm not 10-32. You may want to double check that, but I’m pretty sure it’s right.

The angle is as you said to hold the return spring for the brake. The reason I used angle was to limit the movement once it was all assembled. If I make another set I plan on using fender washers for this purpose, and bending them into an angle. I think it will make a nicer finish, and work just as well. Plus I will get out of drilling at least two holes!

hm…i measure the frame’s hole…and its under 4mm, which sounds right
but i’m able to thread my ~4.9mm bolt into it… I’ll just bring my frame into the hardware store to make sure it fits :slight_smile:
I like the idea of fender washer…but i think it might be easier for me to drill holes in Al then iron/steel…i’ll buy two washers to try.

How do i determine where to drill the small hole…? position where the brakes would be further away, drill hole, place brake onto it and pull the brake closer to rim which tensions then spring and then tighten bolt?

If I rember correctly the bolts are M5 x 4mm. I bought 5mm and cut to the exact length. The angles will keep tension on the brake so it stays off the rim. I experimented here and drilled two different holes. If you use the pictues from this post it shows what you need.

M5 sounds right. For the little holes I put one perpendicular to the fork blade, and another maybe 20 degrees above that. I think I added the higher holes later due to low spring tension.

The length I bought was 45mm however I had to cut them to 40mm.

at the store:
M5 bolts: barely squeeze into one of the holes, cudnt thread into other hole.
#10-32, thread in, but a bit of room…

on the way home, i realized…it’s probably the paint on the frame that prevented me from threading the metric bolts in. I should have put a bit more muscle into it :slight_smile:

either way, they only had 30mm long metric bolts of that size…so I would need to go elsewhere either way.

Should I try using the 10-32 bolt, or am I asking for the threads on the frame to be stripped…(maybe add some loctite and not make it too tight? or is there actually a lot of forces and strength needed to hold the brakes on.)

I have had to chase the threads on all of my uni frames to clean the paint out. Be careful if you are just planning on ramming a bolt in. A tap to do it right is cheap and easy to get. I would use the right bolts. There is too much of a chance that they will pull the threads out if they aren’t a tight fit. I always use blue loctite on brake bolts. Don’t use much, and make sure it doesn’t get onto the post. OEM bolts that come with the brakes already have thread locker on them, so it seems like a good place to use it.