Mini V Brakes - Old Style 65mm Canti Bosses

[deliquium]

1990's Longstaff frame with 65mm c to c canti bosses for older Dia Compe wide arm 982 cantilevers, which means panniers have to be a long way back on the rack to clear the brake arms - and there is lots and lots of heel clearance available to move them forward if the brakes allowed. So fitted some Tektro RX5 mini V's to the rear today - they have 85mm long arms and just clear 32mm tyres and mudguards as seen. Obviously had to to mount the thinner brake pad washers on the rim side. Brake performance is VERY good compared with the Dia Compe cantis - somehwhat snatchy but as it's on the back I think I can get used to it - or use softer pads maybe?

Does the panel see any problem with the arms not being vertical and so much cable between the two arms? I recall once reading a Shimano instruction leaflet stipulating an ideal or maximum length between grown up sized V brake arms.

Clicky pic for much bigger photo - then click again

[cycleruk]

If they work then no worries.
Just keep an eye on the pads, now and again, to make sure they are contacting the rim properly.
The mounting posts (pivots) are probably a little close for the ideal set up and that's why the arms angle outwards.

Longer arm types of V brake would require more cable pull and would be "softer". But then you may not have enough cable pull from the levers to give satisfactory operation.

[Brucey]

it is always a good idea to check the pads on any brake set-up, but yours are less likely to go out of adjustment than with 'modern' 80mm bosses, since your pads are travelling more sideways than downwards when they hit the rim.

That is why older frames have the bosses where they do; they weren't thinking about MTBs or MTB inspired brakes.

BTW you may be able to find a set of brake shoes which is slimmer than normal if you want to bring the arms closer together; (they will be fine as they are though IMHO).

cheers

[deliquium]

it is always a good idea to check the pads on any brake set-up, but yours are less likely to go out of adjustment than with 'modern' 80mm bosses, since your pads are travelling more sideways than downwards when they hit the rim.

The angular adjustment of the convex/concave washers is just enough to get the pads to hit the rims perfectly flat. I could also grind down the concave washer a tad. Also of note, the rims are Exal LX17 with an external width of 22mm - Rigida Snyper and Sputnik would probably be too wide? Impressive braking - off shopping tomorrow so will see with loaded panniers and probably a very sodden rider! Will try some on the front - although they may not have enough modulation? Like decent grown up V brakes, they're so easy to install and set up - I like the flexible noodle.

[531colin]

Brucey is too modest to point it out, but there is some excellent stuff from him on this thread http://forum.ctc.org.uk/viewtopic.php?f=5&t=63112&start=45 about the mechanical advantage of various brake systems.
For me personally, a combination of wide profile cantis and STI levers (designed for dual pivot sidepulls) lacks power.
Mini-vees and STI levers give more power, and I find there is enough modulation, but you will certainly notice the difference until you adapt! You need to run the pads quite close to the rims, and the adjuster on the brake pipe is a plus, you should be able to get the wheel out without a fight.
I don't know how far back you have to go to have levers designed for single pivot sidepulls (presumably non-aero, but what about early aero?), but I think they might be a poor marriage with mini-vees....they pull less cable, so you could end up with the pads brushing the rims, and very little modulation between "off" and "wheel locked".

[deliquium]

Good morning Colin. Thanks for Brucey's link. On the bike pictured the handlebars are now straights (you may recall seeing the bike? with mousetache bars which I decided I didn't like) so have to use Shimano BR-L550 brake levers for canti's as the front brakes are still the original olde worlde Dia Compe 982 cantilevers. Yesterday's brief test run suggested they were fine with the mini Vs on the rear too.

On another bike I have also fitted the Tektro RX5 mini V's for exactly the same reason - to get the panniers much further forward. On that bike the brake levers are Campag Ergo - which do work very well with the mini Vs (on that bike the canti pivots are at the modern 80mm centres so the brake arms are vertical) Front brakes on that are Tektro wide arm 720 cantilevers with Koolstop salmon pads - I find them adequate (meaning I'd like better if possible) so will try your suggestion with front mini Vs.

Cheers, Paul