Brakes for a very narrow front fork

[johnny mcgurk]

Can anyone offer any sound advice?I Am in the process of giving new life to a Dawes super galaxy 1980 ish frame but I have hit a stumbling block with the front brake.The brake bosses are only 55 mm apart and I can't find a brake set that will definitely fit. I originally wanted to fit v-brakes, which were no problem on the rear bosses(they are much wider) but on the front the arms are not even close to vertical. I then tried a pair of avid shortys (they were recommended for narrower forks) but I have the same problem.Undoubtedly I have not helped this by fitting 700 wheels rather than the original 28s??and a slightly wider 21mm rim to allow for fatter tyres.So, does anyone have any suggestions for a brake that will fit or, if not,Does anybody know what the original cantis on the Dawes tourers would have been.Any advice gratefully received.

 

[mickle]

The canti bosses should be 76mm centre to centre so yours are some way out. Did you try shuffling the brake block stud washers around? putting them all on the outside might give you enough but you'll lose any ability to toe the pads in.

28" rims are the same as 700c, it's just a different way of describing the same thing. Unless you mean 27"...

Yours is a problem which occured for a couple of years as manufacturers who had until then been installing cheesy old side pulls (like the ubiquitous Weinmann 405) tried to play catch-up. Cantilevers, developed for tandems, worked their way on to mountain bikes and manufacturers of touring bikes were quick to see the benefits of extra power and clearance. Trouble was, for many of them their forks weren't really suitable. They simply couldn't achieve the 3 inches required. They didn't let that stop them fitting them though..

Trad cantilevers had a much wider range of adjustment than modern linear-pull - more capacity to accomodate canti boss placement error. But still, there were occasions where it was close to impossible to set the brakes up properly and not looking stupid. Bikes such as your Gal required a lot of skill and patience to get right, and the selection of just the right model of brake..

Thanfully most manufacturers were fairly quick to adapt, but it left a lot of bikes on the roads with permanent 'issues'.

I don't recall what your bike came with. Probably Deore or thereabouts. Later 'low-profile' cantilever arms, but not much later 'long-arm'.

Hope that helps!

 

[snailracer]

Have you tried remounting the brake blocks further outboard on each V-brake arm?

Some V-brake blocks are also thinner than others.

 

[mickle]

I'm pretty sure that it's quite a bit later than 1980 if it's fitted with canti bosses. 85+ I'd guess.

If it came with 27" wheels it's almost certainly pre '87.

I never did work in a Dawes dealership so I'm a bit vague about Dawes dates. Sorry.

 

[PpPete]

I'm pretty sure that it's quite a bit later than 1980 if it's fitted with canti bosses. 85+ I'd guess.

If it came with 27" wheels it's almost certainly pre '87.

I never did work in a Dawes dealership so I'm a bit vague about Dawes dates. Sorry.

Pretty accurate for someone vague !
We have a pair of Galaxys (not Super Galaxy) that were bought in early 88. May have been 1987 model year. 700c and Canti bosses - but both were "recent changes".

They were originally fitted with very early model Shimano Deore Cantilevers - the wide sort that are now known as Cyclocross or Froggleg brakes. Shimano only made those for a very short period of time, and I've never seen them on sale, even 2nd hand on Ebay. Shimano changed, I believe, to short arm cantis (more like the Tektro Oryx) because of product liability reasons, and the perception that a too-short straddle wire could catch in a knobbly tyre.

My suggestion for the OP would be Tektro CR520 (or CR720) - but change the pads to Koolstop Salmon or DualCompound.

I run the Dual Compound pads on the original Deore front cantis and they are excellent brakes. I put a Suntour SE (Petersen System) on the back to give a more braking force on the rear and make rack fitting easier - with the DualCompounds it's almost too easy to lock the back wheel up.

 

[bikepete]

Try Magura hydraulics - beg/borrow a set initially to test fit perhaps - the reversible mounting gizmos can 'win' you about 8mm each side IIRC. I've used them on several bikes which had well wonky canti bosses which nothing else would work on. The pistons are fitted into the mountings by a sort of spherical socket arrangement, and also slide in and out, so you can compensate for all sorts of dodgy geometry.

Pic here (not my auction) shows them at their 'widest' setting pretty much:

http://www.ebay.co.uk/itm/110766473999

As you can see the mounting brackets 'step' outwards a bit as shown. In the pic the 'booster' plate is holding the two sides apart but you can imagine the canti bosses can be a fair bit closer together before the pads get close to a sensible rim width apart.

Limits you to flat bars mind (Magura levers for drops are no longer made AFAIK and like hen's teeth used). And you may have to modify/make a booster to suit the narrower width if the original doesn't fit (otherwise the pistons are powerful enough to flex the fork, especially an older touring bike one).

But if you get them fitted properly braking will be superb.

 

[Rohloff_Brompton_Rider]

change the fork. sjs have some lovely cromo ones for £35 iirc. i've just got some for my next fixie, very nice indeed.

 

[mickle]

change the fork. sjs have some lovely cromo ones for £35 iirc. i've just got some for my next fixie, very nice indeed.

Careful now! The rake on a mid eighties tourer is a little different to a modern road-fixed.

 

[Rohloff_Brompton_Rider]

they are tourer forks.

have a look see what you think....


then there's always ebay or second hand shops for date correct ones, better than having shitty front brake (which we all know is THE most important one)

 

[johnny mcgurk]

Many thanks for all your replies. I would like to try and keep the original fork (call me old fashioned) but I guess replacing it would be a back stop. Bromptonfb thanks for the heads up on those sjs forks...good price.Mickle your comment about patience and skill worries me, patience I have a bit of, but lacking the other commodity.Pppete I looked at the tektro cantis and they looked very similar to the avid shortys. Do you know something I don't.The problem seems to be one of angle as much as width. With all the fittings on one side I can get the pads to fit but only a small part of the pads surface contacts the rim when the brake is engaged.

 

[Rohloff_Brompton_Rider]

what about on-one mini v's? they will work with your existing levers. i have a set on my fixie and they very good....at £10 for front AND rear good value too.

 

[RecordAceFromNew]

Fwiw I wonder if the following is the canti profile PpPete talked about that works for him. They were sold until around '86, so matching Mickle's dating. Relevant Shimano codes appear to be BR-MC70, BR-MT60 or BR-AT50. IF they are the right ones then while rare they are available from time to time. But I wonder if one can't find modern geometric equivalents (because I suspect geometry is all that matters for the present purpose).

Assuming that the pad pivot of these or similar cantis can allow suitable pads to hit the rim squarely, canti setup for maximum power is ALL about optimal straddle wire length (albeit that may interefere with tyre/mud but one won't know until one tries). The science of optimal straddle wire length is complex, but IME works, and is probably worth pursuing by the OP, whom we hear has plenty of patience...

 

[mickle]

These have got to be the ones haven't they? Replace the straddle wire and straddle hanger for a stock set-up and replace the brake blocks for some with regular posts...



BR-CX70 Cyclocross Cantilever Brake

 

[PpPete]

Mine are the BR-AT50... and they look like the ones in RAFN's post. And yes the studs on the forks are only 55 mm apart too.

My (subjective) impression is that the type where the arms go up at near 45 deg (like the BR-CX70 pictured above) or the Avid Shorty (below) are not as effective as those with near-horizontal arms.

Also the Avid Shortys are expensive.

The Tektros are about a quarter of the price - and use V-brake style pads so are very easily adjustable to get all the pad square on the rim. The pad alignment adjustment of the BR-AT50 is much difficult.

 

[johnny mcgurk]

I have never found a close up pic of the originals so pppete would have to confirm but on the other hand those BR-CX70 Cyclocross Cantilever Brakes are truly things of great beauty. Might have to give them a whirl with a standard set of blocks. Thanks for the research Mickle.