Converting A 4bolt Frame To Vee Mounts

[Luke Rainbird]

Hey guys,

I've been considering this for a while now, but thought I'd open it up a bit by posting it up here for some feedback/opinions;

As a vee user, it can be frustrating having a very small choice of frames available with dedicated vee brake mounts, and as such I have to use a set of Heatsink Vee adaptors.

These are a brilliant solution to the issue, however they still leave some room for flex, raise the brake further from the stays themselves, and add weight which is so often an issue nowadays in trials. The arms also mount a touch further down the stays, meaning you get less overall leverage on the brake - not so much an issue with my Ultimate, but maybe more so with cheaper arms (SD5 etc)

A while back, when I decided to go vee, I sent my frame off to the excellent Mr Edward Potts, as the frame had been helicoiled to M6 and required M5 threading for the adaptors to work at their best. Sir Potts removed the helicoils, and proceeded to put in place an M8 insert with M5 internal threads, solving the issue.

This, however, got me thinking. If an M8 insert is able to work, what is there to stop somebody putting a set of vee lugs in instead?

The only real issue I can see with this is the fact that there will be no holes for locating the tensioning spring for the brake, perhaps solvable with a small plate sandwiched between the lug and the frame itself?

Discuss...

[Bionic Balls]

i guess you mean like those cheap mission adaptors? i'm sure i've seen a few pictures of those snapping at the top of the M5 thread...all the stress from the brake is going into one M5 bolt when it's usually shared between two (4 bolt magura)..so you'd just have a beefier one of these?

8mm is a bloody big hole...not sure if there's really enough material- how close is it on your frame?

if you look at proper v mounts...they're really quite beasty- like a chunk welded on...

i'v just converted to v brake..and i love it ...need to find a decent booster though...

adam

EDIT: - chunkier ones of those?

Edited March 15, 2008 by zhi nuts!

[Luke Rainbird]

i guess you mean like those cheap mission adaptors? i'm sure i've seen a few pictures of those snapping at the top of the M5 thread...all the stress from the brake is going into one M5 bolt when it's usually shared between two (4 bolt magura)..so you'd just have a beefier one of these?

8mm is a bloody big hole...not sure if there's really enough material- how close is it on your frame?

if you look at proper v mounts...they're really quite beasty- like a chunk welded on...

No adaptors, making the frame itself have vee mounts.

Tapping an M8 thread into the frame, and whacking a set of these (plus lots of threadlock ) in

There's plenty of material on the mounts currently on my frame, and I'd imagine more on some of the later Deng CNC lumps

Edited March 15, 2008 by Monkey Boy

[basher]

I think its a great idea and someone should try it. But the problem is that once youve done it youve narrowed the chance of being able to sell it on afterwards.

[Luke Rainbird]

Yeah, I'm tempted to give it a shot, and I'd imagine you can just stick another insert in if you don't like it - stronger than original threads/helicoil so shouldn't be an issue, unless it snaps the mount

[*Tom*]

What about the position of the mounts to the rim?, would the pivvot be in the right place for the pad to hit the rim ect, i know theres adjustment on the vee arms, but on all the adaptors i've seen the pivviot sits below the bottom four bolt mount.

[trials_pimp]

It could work, maybe have a small round plate with the 3 pin holes in with an M8 hole in the middle, with a small straight peice with an M5 hole in to go in the top 4 bolt mount to stop it twisting and loosing spring tension.

The problem being is M8 is going to be right on the limits of the material of the Magura mount on the frame, and with the forces of braking could leave it very suseptable to cracking or braking off.

Its a bit of a counter-evolution, as trails frames spent years to get 4 bolt mounts on them, and with the amount of people using maguras I cant see many manufactureres going back to post mounts.

There are still a few frames left, like the Phase 1.3 (same as the other frames but with post mounts)

I cant see trials taking a step back and everyone going back to V brakes, not when Maguras are currently so good, and now the Echo brakes have got a foot in the choise is better than ever.

[Matt Burrows]

What about the position of the mounts to the rim?, would the pivvot be in the right place for the pad to hit the rim ect, i know theres adjustment on the vee arms, but on all the adaptors i've seen the pivviot sits below the bottom four bolt mount.

Yeah I think that would be an issue on a lot of frames. Its a shame the Heatsink adaptors weren't better designed in the first place, your right when you say they sit too high up. I've got an Avid Arch Supreme V I want to try on the back, but I imagine it will probably be flexy. Unlike most Vs it doesn't use those 3 little holes to provide spring tension so would be perfect for your idea. I'm not sure I want to drill big holes into any of my frames though...

[Luke Rainbird]

These are a brilliant solution to the issue, however... The arms also mount a touch further down the stays, meaning you get less overall leverage on the brake - not so much an issue with my Ultimate, but maybe more so with cheaper arms (SD5 etc)

What about the position of the mounts to the rim?, would the pivvot be in the right place for the pad to hit the rim ect, i know theres adjustment on the vee arms, but on all the adaptors i've seen the pivviot sits below the bottom four bolt mount.

The adaptors I'm currently running position the vee pivot about 10mm below the bottom mount, and force me to run the pads as far up the arm as possible. Moving this pivot up a touch gives more room for pad adjustment, and greater leverage, leading to more braking power

It could work, maybe have a small round plate with the 3 pin holes in with an M8 hole in the middle, with a small straight peice with an M5 hole in to go in the top 4 bolt mount to stop it twisting and loosing spring tension.

The problem being is M8 is going to be right on the limits of the material of the Magura mount on the frame, and with the forces of braking could leave it very suseptable to cracking or braking off.

Its a bit of a counter-evolution, as trails frames spent years to get 4 bolt mounts on them, and with the amount of people using maguras I cant see many manufactureres going back to post mounts.

There are still a few frames left, like the Phase 1.3 (same as the other frames but with post mounts)

I cant see trials taking a step back and everyone going back to V brakes, not when Maguras are currently so good, and now the Echo brakes have got a foot in the choise is better than ever.

A lot of riders run vees, due to them (when set up correctly) easily matching, if not exceeding the performance of their hydraulic counterparts. It's not so much a step backwards in that respect. The major manufacturers just seem to ignore the fact that a lot of people run vees, and because of this don't even give the option.

The plate extension to the top mount could be a nice idea (I personally would like to eliminate the top mount if possible, but that would of course depend on the structural stability of using only the lower. With the current M8 insert in the frame, there is still a couple of mm of material around the insert. Obviously it would be nice if there were more, hence the discussion to see how solid it may be

[totaltrials]

I totally agree with this, the heatsink mounts are slightly too low and high up and could be a fair bit lighter.

The reason they are that high is to give clearance for the Pad holdings. What would have made sense is to make it a lot lower and drop the center of the mount (like one side of a 4-bolt mount) giving space for the brake pads and having it much lower.

I'm currently modifying mine which will lower the mounts a fair bit, i'll post some pics when i'm done.

Phil.

[abtrials]

i thought you was using a zenith frame?? they are the best for v set ups nice and lowe??

also i have modified a frame and cut the 4 bolt mounts short so the adaptor sits closer to the frame, works real well

also i have left just enough to run a maggie as well

[Luke Rainbird]

i thought you was using a zenith frame?? they are the best for v set ups nice and lowe??

Nope. How do you mean low? As in, further down the seat stays (towards the dropout) or low profile? If there was another mm or so on the Zenith dropouts I would have probably tried it

also i have modified a frame and cut the 4 bolt mounts short so the adaptor sits closer to the frame, works real well

also i have left just enough to run a maggie as well

Pic?

[Dan6061]

I got Edd to make me some adapters for my Zona, and the only problem I had with them, was that the Vee mount sat too low down for my frame. So I had to have an extra link in my frame, and have the wheel at the end of the dropouts...

So I bought some aluminium, and started measuring out my new adapters.

The desgin Edd made, has the Vee mount threaded the whole way through, then it is held on by a short M6 bolt at the bottom. So with my new design with the Vee mount higher up, this bolt head got in the way of the bolt for the bottom Magura adapter.

So instead of a bolt, I cut up a nail, and put that in the whole for the bottom Magura mount, so it just sits inside the mount stopping the adapter from pivoting. Then the top bolt holds it all down.

It works fine, although the aluminium I used was a bit thin, so it bends a little bit...