Upgrading a 90’s MTB. Went with 27.5” wheels and using a Paul Motolite brake in the rear since it has a lot of vertical pad adjustment. The issue is that the cable guide is not high enough to clear the tire. Any suggestions? Or know of a v-brake with longer arms and sufficient pad adjustment? Thanks.
by robj1967
14 Comments
The issue here is not the arms but the location of the bosses on the frame. Hence the reason conversations are usually a PITA unless you’re working with disc brakes. Someone might make something that works. But it’ll mess with the lever feel. It’ll probably take trial and error, or a switch to a center pull brake. If you’re really set on 27.5″ then center pull brakes will probably be your cleanest solution.
You could add a component to the left hand arm which limits the motion of the silver noodle holder with “PAUL” on it? Or replace the noodle holder with a modified one that has a limiting feature?
Something like a small aluminium collar might do the trick.
Just an idea. [Aluminium Split Collar](https://www.amazon.co.uk/Tlilyy-Collar-Aluminium-One-Piece-Thickness/dp/B0CKVMKNHS)
Might just be enough to give you the clearance you need, though muddy days might be an issue, and mudguards wouldn’t work.
Alternatively, go 26” rear, 27.5” front
Whats the width of your tires? This might be a limitation you just have to accept. I have a 650b converted 26er and I’m pretty limited not just by the frame but by the brakes I’m using. I’m maxed out at 650b x 48mm, I could probably get away with 50mm tires but I don’t wanna run such tight tolerances on parts that move so much.
I will say after looking at it again- looks like your noodle is resting on the brake, you could try shortening the cable housing so that it’s less slack and functionally it should just lift the noodle up and MAYBE it will lift the floating “PAUL” part that the noodle slots into as well.
You might be able to get a mm or two additional height by using the small concave washers on the inside of the brake arms, getting the arms a tad more vertical. And then if the bale only rubs a little bit when hitting rough stuff, landing jumps/bunnyhops, etc, you might try out a rigid noodle, perhaps that wouldn’t allow as much sag.
look for v brake extender on ali. i’ve seen a few different models in the past, though i don’t have any experience with them.
Skinnier tire.
https://shop.plainbicycle.org/products/promax-brake-post-extenders
No judgment here, but I absolutely do not understand the purpose of a 26”-to-650b rim brake MTB conversion.
It looks like it might clear if the arms close more. Can you flip the barke hardware around to space the pads wider? It looks like the bigger angle washer is on the inside.
Cantis are terrible, but they’re a good solution for 650b in a vintage frame.
There are also some super long reach vbrakes. Most max out around 110~114mm, but I think these 120mm ones are what I’ve currently got sitting in my parts bin:
https://hollandbikeshop.com/en-gb/branded-bicycle-parts/contec/contec-bicycle-brakes/contec-brake-set-v-brake/contec-v-brake-br-849al-120mm-arms-silver/
90’s bikes are built for 26”.
You can get a few mm clearance if you roatate the cable clamp so that the cable enters the clamp more vertically.
That’s about all you can do with that set up unless you’re happy to let it self clearance.
Or crank up the spring tension. Might get you there, but I doubt it.
Maybe i always see problems but that wheel isn’t even close to the center of the stays.
So before you talk about brake problems check wheel dish and frame alignment something is way off there with the wheel over to the right side like that. Then deal with the Frankenstein issues of converting a bike to mismatched shit that doesnt work.
But thats what most people do is look at the last problem and ignore all the underlying factors. The clearance on the wire could be solved with a smaller tire after you center the wheel somehow .
Besides the Brakes just slow the bike down. And it’s not an upgrade to create problems that weren’t there with the original wheels. Most people don’t Realize there is a reason that OEMs work and their patch together things don’t. Its because manufacturers aren’t “Experimenting” but instead cranking out thousands of bikes all in a row with the correct shit .