UPDATE - Problems upgrading brakes on old road frame

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LollyKat
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UPDATE - Problems upgrading brakes on old road frame

Postby LollyKat » 27 Jun 2011, 3:25pm

I have a King of Mercia touring bike from about 1987 with drop bars and cantilevers. The brakes have never been very satisfactory because of the low-profile cantis which were all that I could get at the time. Also the frame was advertised as suitable for 27" or 700c wheels, but since changing some time ago to 700c the brake pads have to be at the very bottom of the slot and even then barely fit.

Anyway, I got the idea from elsewhere on the forum that I could fit v-brakes with special levers (I'm happy enough with downtube friction shifters). I duly bought a set of Avid Single Digit 5s and some Tektro RL520 levers. However there is not enough room to fit the brake pads as the brake mounting bosses on the front fork are only 62.5mm apart. The rimes are Super Champions which need replacing, so I can get something a little narrower, but even with that and swapping the spacers on the brake blocks around I am still not sure they are going to fit.

All thoughts and suggestions gratefully received.
Last edited by LollyKat on 11 Jul 2011, 11:39pm, edited 1 time in total.

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531colin
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Re: Problems upgrading brakes on old road frame

Postby 531colin » 27 Jun 2011, 4:33pm

There are pictures here http://forum.ctc.org.uk/viewtopic.php?f=5&t=44074&hilit=brakes&start=15 of a bodge I did when faced with the same situation. These are old fashioned ATB cantis where by chance I was able to get the blocks low enough, and I then shortened the arms to get back to the right leverage.
It is a working bodge, but you do need to keep on top of the brake adjustment.
I may have posted it twice, because I remember somebody criticising it saying the rim was too low to the brake mounts, resulting in the brake blocks describing a small radius arc, and they would quickly move down the rim as they wear. This is, of course, the problem at the outset. There may have been other criticisms, which you may find if you search more diligently than me!
I probably have the brakes knocking about still, I can dig them out if you are interested, and post them to you, if they work for you we can agree a price.**
The proper answer is to have the old canti mounts removed and new ones fitted and the frame resprayed....or remove them yourself and use long drop dual pivots!

**like swap for your V brake drop levers, if you are not using them!

LollyKat
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Re: Problems upgrading brakes on old road frame

Postby LollyKat » 27 Jun 2011, 9:56pm

Thanks for the input.... decisions, decisions! My current Shimano cantis work reasonably (with their old-style levers), if kept closely adjusted, but the front one never hangs straight because of the way the cable leaves the hanger. Since the V drop levers pull more cable, do you think they would work with these mid-profile cantis? At the moment I have old Weinmann levers with the cable sprouting out of the tops, but they are getting pretty worn and I would really like some aero levers.

The frame could do with a respray, though, and I have wondered about getting the bosses moved down. Wouldn't it weaken the 531 forks to do a rebraze in almost the same spot? Would cantis, properly fitted, be better than long-drop dual-pivot side-pulls? Would decent cantis such as frogleggs fit or would the forks still be too narrow? Of course I could get a new fork but am just wondering where it's all going to end.... I'd also get the back widened from its current 126mm.

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531colin
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Re: Problems upgrading brakes on old road frame

Postby 531colin » 27 Jun 2011, 10:26pm

There are so many threads on here about brakes!! You may find some really relevant stuff if you search better than me!
Easy question first....V levers and cantis. of any description are a no-no.
You need new bosses to get the new (front) spacing, I don't think the re-brazing is a problem, but ask your builder.
I've probably got some spare aero levers, too!
Cantis better than long drop dual pivot brakes....I think thats a "that depends" answer. Decent cantis, well set up are better than poor dual pivots, and vise versa!
Pictures below from this thread..http://forum.ctc.org.uk/viewtopic.php?f=5&t=43448&hilit=humpty+dumpty&start=15..............
These Tektro 720 cantis are at least as good as expensive "frog leg" clonesImage, they need new pivot spacing
these old Shimano are more powerful and would also fit the narrow or wide bosses, except they need moving down anyway!..Image
This guy http://www.defietsenmaker.nl/index.php?item=shimano-br-mt60-cantilever-brake-set--_-1980_s&action=article&group_id=32&aid=353&lang=EN may still have some..(or - guess what? I do!)
Setting up cantis is here http://forum.ctc.org.uk/viewtopic.php?f=5&t=33329

I'm all linked out now!
Last edited by 531colin on 30 Jun 2011, 11:22am, edited 1 time in total.

Wesh-Laurence
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Re: Problems upgrading brakes on old road frame

Postby Wesh-Laurence » 28 Jun 2011, 10:25am

If you are going to use V-Brakes with "road" drop handlebar brake levers you need to use Mini V-Brakes which have shorter lever arms. The "road" brake levers pull less cable than "mountain bike" brake levers on flat handelbars and "normal" V-Brakes won't work with "road" drop handlebar brake levers.

I don't know if the brake blocks on Mini V-Brakes would line up correctly on your rims.

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531colin
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Re: Problems upgrading brakes on old road frame

Postby 531colin » 28 Jun 2011, 2:05pm

Full size V brakes are fine with V brake specific drop bar levers.
Mini V's would struggle to clear mudguards on a bike built for 27" wheels, I think.

LollyKat
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Re: Problems upgrading brakes on old road frame

Postby LollyKat » 28 Jun 2011, 9:35pm

Colin, many thanks for your links and comments. I did search before posting, finding several recommendations like this:
Keep your drops, fit V brakes, V brake drop levers, and bar end shifters.
Great brakes, and use any F. mech you like, that shift isnt indexed.
Simples!

but didn't realise that front forks had got wider, which is what is really causing the problem, as at the bottom of the slot the Avid brake blocks do reach the rim.

I'll need to think this one over...those old brakes of yours are very tempting :wink: .

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531colin
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Re: Problems upgrading brakes on old road frame

Postby 531colin » 28 Jun 2011, 10:40pm

I'm happy to send them to you to play with.

LollyKat
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Re: Problems upgrading brakes on old road frame

Postby LollyKat » 29 Jun 2011, 3:39pm

Thanks - you have a PM :)

LollyKat
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Joined: 28 May 2011, 11:25pm
Location: Scotland

Re: Problems upgrading brakes on old road frame

Postby LollyKat » 11 Jul 2011, 11:39pm

Just to update, Colin sent me some brakes to try. The old Shimano ones, which he had slightly modified to give an extra couple of mm adjustment, fitted and work a treat. I'm looking forward to be able to go whizzing downhill again!

Many thanks, Colin - you're a star!