Yet Another Cycling Forum
General Category => The Knowledge => Topic started by: mrcharly-YHT on 16 July, 2018, 05:01:10 pm
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One return spring has broken on the front brake on my clunker/town bike.
Said brake is a BMX/U-brake type.
I'd just replace it with a V brake, except that the posts don't have any bits to take the return spring (no plate with holes in it). Instead, there is a removable plate with a grooved flange *above* the post. This looks to be specific to the U-brake. Two bike shop mechanics sucked teeth at it and said I'd have to find a like-for-like replacement.
Best option I can think of is to find an old BMX with similar U-brake. Anyone have other ideas?
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A U-brake isn't a difficult thing to find, my wholesalers keep them on the shelf. Not expensive either.
A picture is worth a thousand words - Well, at least it would help to visualise the current fitting.
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That bike's U-brake posts allows you to fit a U-brake (or old roller cam) brake. Many (all?) of them had adjustable spring tension without the end of a spring sticking into a hole. The springs were tightened with a spanner and locked in position when the central bolt was tightened. See the pictures at the top of https://www.sheldonbrown.com/canti-u.html
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If the 'adapter' is bolted thru the fork crown then we just need to know the vertical distance between the hole in the fork crown and the rim. Then it's a cinch to find the correct drop side pull.
Or have I read it wrong...?
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*Lightbulb moment*
This isn't a 'pit bull' type brake is it? The cable pulls a wedge between two rollers?
If it is, I've got one...
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A Pitbull would be a drop in replacement for a U-brake on an adaptor plate.
I've never tried but the Pitbull arms might fit onto U-brake posts. You'd still need the cable stop mounted somewhere.
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it might well be the case that a pair of springs from a cheap V brake could be made to work with the U brake.
cheers
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Please put me out of my misery, I can't picture it.
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U brake adaptor
(http://i.ebayimg.com/images/i/321895520435-0-1/s-l1000.jpg)
they often have slots/holes in for return springs, but I think the one above doesn't have that.
The net result of using one of these things is that you have created an oversized centre-pull brake.... ::-)
cheers
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OK, got it.
So we go back to the suggestion of measuring the drop and fitting an appropriate sidepull instead.
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It is on posts - no adapter
I doubt a sidepull would fit (apart from some of the really odd cheap BMX ones. I have 1.75" tyres.
Will try to get a photo posted up.
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Just buy another U-brake (they aren't too expensive) and fit it. http://cycle-systems.co.uk/tutorial123/brakes-set-bmx-u-brakes-front shows how to adjust brake spring tension.
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replacement springs?
https://www.ebay.co.uk/itm/Dia-Compe-Hombre-U-Brake-Springs-Left-and-Right-Pair-no16/123243973368?hash=item1cb1e9caf8%3Ag%3AeaEAAOSw6fVaizMt&_sacat=0&_nkw=u+brake&_from=R40&rt=nc&_trksid=m570.l1313
or
https://www.ebay.co.uk/itm/Dia-Compe-AD990-FS990-U-Brake-Springs-Left-and-Right-Pair-no15/112825131316?hash=item1a44e6e134:g:~T0AAOSw8i9aizPQ
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It is on posts - no adapter
ah... I assumed it must be adjustable in some way if you were considering a V brake. V-brakes and U brakes require the posts in completely different positions; the only brake that will fit on fixed U brake posts is another U brake.
As I mentioned earlier springs from a cheap V brake might work though.
cheers