Cantilever to mini v brakes 2005 Dawes Galaxy

[epa611]

As the title says, I want to try mini v brakes on my Dawes Galaxy to see if they're better than the original Oryx cantis.

My drive train is Smergo'd with 07 Veloce ergos and Deore 9sp rear.

What size of mini v's will in need? 80mm, 85mm or 90mm?

TIA.

Paul

I'm a trendy consumer. Just look at my D5803 using hovercraft full of eels.

[meic]

I am guessing that you have already done a search and read about other people making this change.

The first point that I would make, is do you need to do both brakes for conformity across the bike, or would you be happy to do just the front one (as I have done)?
The reasons are, that the cantilever brakes are powerful enough for rear use and that the rear wheel deflects more while riding due to the power going through it.

The minimum size that the brake arms can be is set by what size tyres and how close any mudguard is, the maximum size is set by how much pull you can tune out of your cable and how close to the rims you can bare to set the pads.

In practice you will also need to introduce a cable adjuster into the system if you dont already have one as adjustments are needed frequently, things are so close to the limit with these brakes that you need to adjust for brake pad wear, even a millimetre of it!

I cant remember if mine are RX5 with 85mm or 926 with 80mm but the cable is scratching the close fitting mudguard and the pads are only a hair's breadth from the rims.

[bikepacker]

One my wife's Galaxy I have Tektro 80mm mini vs and they work good with her Sora stis. Although there is only a small amount of clearance on the top of the mudguard when brakes are applied. On my two touring bikes I have Shimano Tiagara road vs which are 90 mm. Personally I can't tell the difference.

I do have here a complete front and rear new set of Tektro mini vs which I got to do a conversion and the misplaced them. Only found them a few weeks back. You can have them for £15 posted. pm me if interested.

[meic]

Here is a picture, which inspired me to give it a go.
viewtopic.php?f=1&t=99163&p=924272&hilit=35mm#p924272

He has used the RX6 which is 90mm, so a bit more room for tyres and mudguards but uses up more valuable cable pull, so less pad clearance (less tolerance of wobbly rims) and tolerance of bad cabling.

If you are out touring, it is generally a bad idea to start right on the edge of your tolerances.
The braking benefits are however quite great, so for me a miniV on the front but leave the cantis on the rear.

[MikeDee]

They have these things called Travel Agents where you could use full sized V-brakes with your short pull levers, but read they are not as good as mini V's. The Tektro RX-5 mini V's are nice brakes, but the pads aren't. I replaced the pads with Kool Stops.

[Brucey]

Here is a picture, which inspired me to give it a go.
viewtopic.php?f=1&t=99163&p=924272&hilit=35mm#p924272

He has used the RX6 which is 90mm, so a bit more room for tyres and mudguards but uses up more valuable cable pull, so less pad clearance (less tolerance of wobbly rims) and tolerance of bad cabling.

If you are out touring, it is generally a bad idea to start right on the edge of your tolerances.
The braking benefits are however quite great, so for me a miniV on the front but leave the cantis on the rear.

this picture?



one thing that stands out for me in that picture is that the brake bosses appear to be set slightly higher than some are on those forks. This has two effects;

first it makes more clearance for tyres and mudguards with any given length of V brake.

secondly it makes the caliper MA a bit higher than it might be otherwise. In the picture the caliper MA is about as much as it is with many full Vs on some other frames.

Anyway frames and forks vary; if the bosses are set a bit lower vs the wheel rim on another frame, there will be less MA and less clearance for mudguards, and perhaps slightly more running clearance at the brake. I have one frame where a full V offers about the same mudguard clearance on slightly fatter tyres, because the bosses are set very low. On this bike I can use (short pull) levers for cantis, even with full Vs.

cheers

[fatboy]

Does your Galaxy still have the original bar end shifters? If it does I'd consider using full size vees.

I tried mini vees on my Horizon of a similar age and it wasn't that successful. In the end I got my Oryx to work better by the following:

1. Better pads (Koolstop)
2. New straddle for the front and an uphanger (stops the fork judder and better MA)
3. Changed the routing of the rear cable as the cable run was very poor

In the end they are pretty good

[cameraman]

I've never been satisfied with the braking performance of Cantilever brakes, back in the day when Cantis were the only choice for MTB's I hated them, couldn't wait to get V brakes (Shimano M739 still have them on my sons run around). Last year I bought a cheap CX bike for commuting with canti's, Shimano ones they were ok in the dry but useless in the wet, I bought some Tektro CR720 cantis thinking the longer arms would give more leverage, no still pretty useless. I read Sheldon Browns wisdom on setting them up and tried various lengths of straddle cable, some more useless than others. I then bought another frame that had TRP cantis, the seller telling me how he out braked disc braked bikes in the races and having used TRP long drop brakes on my Winter trainer I was hopeful of great things, but again lacking in any real stopping power, I was using the bike for commuting in Central London and in the wet it was simply dangerous, I even tried SwissStoop BXP pads which transformed the brakes into mildly usable. I had some Shimano XT M770 V brakes in the spares box and decided to bite the bullet and try them with the help of Problem Solvers Travel Agents, I'd read that mini V's weren't worth the effort, I also fitted SwissStop GHP pads, at last I had dependable powerful braking in all conditions, the only downside was rough feeling levers thanks to the extra mechanical gubbins of the travel agents. Never happy unless I had perfection and thanks to a forum user offering a new set of TRP CX9 mini V brakes for £50 I took the plunge and gave them a go, couldn't be happier braking performance at least as good as the XT's if not better, nice smooth progressive braking and easy to lock up ether wheel if the need requires

[cameraman]

By the way, I'm using standard Shimano STI lever/shifters (currently Tiagra 4700), the pic shows CX tyres but I have clearance for road tyres and mudguards front and rear.

[Brucey]

I've never been satisfied with the braking performance of Cantilever brakes, back in the day when Cantis were the only choice for MTB's I hated them, couldn't wait to get V brakes (Shimano M739 still have them on my sons run around). Last year I bought a cheap CX bike for commuting with canti's, Shimano ones they were ok in the dry but useless in the wet, I bought some Tektro CR720 cantis thinking the longer arms would give more leverage, no still pretty useless. I read Sheldon Browns wisdom on setting them up and tried various lengths of straddle cable, some more useless than others....

with CR720 you were pretty much wasting your time messing about with straddle length; those brakes have almost horizontal arms and you cannot vary the MA very much. Maybe 5 or 10%, typically. They don't have a super high MA to start with because they are meant for CX racing, where running clearance is as important as MA. Just like cantis that were used on most MTBs, to start with, too.

You don't say which shimano and which TRP cantis you tried, but if either of them had mid-length arms then you should have tried varying the straddle cable height with those. You can sometimes double the MA with changes in setup.

It is thus possible (with the right levers) to get canti setups with the same MA as a V-brake and when you do this they work as well (obviously...). You do need to be more scrupulous about cables though, because the tension in the cables is higher with cantis than with Vs.

I have one bike with cantis where I have gone for it, MA wise, and I can easily chuck myself over the handlebars with two fingers if I want to. They are every bit as powerful as V brakes. No special parts, just carefully chosen ones, carefully set up, no time-wasting with inevitably fruitless endeavours...

cheers