Brakes for a bike with 32 or 35 mm tyres

[bornagain]

Hi Guys

I'm going to build up a new bike for commuting & winter/wet weather rides.

The frame will be a Van Nich Amazon, 105 STI groupset & DT Swiss 1900 wheels.

The tyres will either be 32 or 35 mm and I don't know what brakes will fit - my cross bike with 35 mm tyres has froglegg brakes, but that is because of the potential for the build up of crud when off road - they are a paid to get set up and need regular adjustment.

For a road bike, what brakes will work with fat tyres and STI levers ? Ideally I would get dual pivot 105 brakes but I suspect that they won't fit.

Any opinions would be gratefully accepted....

P

 

[MartinC]

First you need to establish what the frame and forks will allow. Does it have brake bosses for V or Canti brakes and/or is it drilled for caliper brake. Whether you want to use mudguards is also a factor.

First question is what size tyres will the frame clearances allow you to use and do you want to use some of this for mudguards?

A frame set up with the maximum clearnce for 57mm drop caliper brakes will generally allow you to use 28mm tyres with mudguards or 32mm without. 35mm will probably be a tight fit.

If it's set up for 49mm drop calipers then you might fit mudguards and 23mm tyres but no more.

If it has bosses for canti/V brakes then you'll have to measure the clearances and see what you can fit. Generally this sort of frame will allow you fit 35mm tyres and mudguards.

If you want to use STI's then the choice of brakes is:

Cantis - old fashioned high profile ones (e.g. Froglegs, Tektro CR720's) often work better than modern low profile ones (e.g. Shimano BR550's, Tektro Oryx).

V brakes - you'll have to use a Travel Adaptor to get them to work properly with the STI's

Mini V brakes - these may or may not fit (provide enough clearance) and the may not work satisfactorily (still require too much cable pull) - you have to try them and see.

Hope this helps.

 

[NickM]

STI levers don't pull enough cable to operate mini-Vs satisfactorily (let alone V-brakes). I have tried travel adaptors and found them annoying - difficult to get working well again after a wheel has been removed. I would advocate sticking with cantilever brakes on an Amazon.

The best cantilevers I have used are old-fashioned wide-profile Shimanos (Deore or Deore XT) with Koolstop Salmon blocks. I reckon you won't find these other than on eBay now. The current Shimano equivalent is the R-550, and if the Froglegs are not working well they might be your best bet.

 

[MartinC]

Whether STI (or standard drop bar levers) pull enough cable for mini-V's to work depends entirely on the individual set up. In my experience the height of the pads above the bosses is the crucial factor. You can work out the geometry. There's usually about 25mm of height adjustment for the pads, if your bosses put the pads at the top of the slots you'll need less cable pull than if they put them at the bottom. I've got an STI/miniV set up that works fine. I'm lucky, I know it often doesn't work for others so you can only try it and see. As I said, I think the crucial factor is where the pads are in the adjustment slots

 

[NickM]

Whether STI (or standard drop bar levers) pull enough cable for mini-V's to work depends entirely on the individual set up... I've got an STI/miniV set up that works fine...

I should have said "In my experience..."! However, it's a rather expensive experiment unless you can borrow a set...

 

[MartinC]

I should have said "In my experience..."! However, it's a rather expensive experiment unless you can borrow a set...

Yes it can be, but you can work out how much pad movement you'll get from the lever/brake combination beforehand if you want to see if it's a worthwhile experiment. Basically if the pad movement at full cable pull from your chosen set up is the same as or greater than the pad movement from full size V's at minimum pad height (about 5mm) then it'll probably work.

Canti's require some experiment too. Some people can never get acceptable performance from semi low profile canti's. Even with high profile ones you'll need to get the hanger adjustment right and judder may be a problem with flexible forks.

 

[New Horizon]

The VN Amazon frame has mountings for cantilever/V brakes. If you're using STI road then it will have to be cantilevers (I don't think Travel Agents should be encouraged)- I have Shimano BR550's on mine and they work fine after a lot of fettling and no help from VN. To avoid the judder with carbon forks that mine came with, recommend a fork hanger like this one (picture is upside down) - http://www.dotbike.com/ProductsF.aspx?FIND=kona

I fitted one, with a JagWire inline adjuster and it's stopped the judder and improved the brakes. For the rear, I sourced a Surly stainless brake hanger. It’s a shame VN didn't put more thought into the brake design for this model.

I'm running 32's and there is plenty of room, 35 is ok even 38's would probably fit without a problem.