breadbin

have an mtb with shimano lx v-brakes and a 26" mtb rim. the problem is that in the normal middle hole there is no spring tension and the brakes don't come out from the rim when released. i move the pin into the top hole increasing the tension and works perfectly apart from the fact the brake blocks won't go near the rim. they hit the tyre and try as i might i can't lower them to make contact with the rim. whats the story with this? is there anything else i can do?

oldbobcat

Too hard to tell without a photo.

jimc101

The middle hole should work for most shimano v-brakes.

There is a adjustor screw on each arm, this is used to increase, and decrease tension, have you tried using this? also, is the cable correctly set up as per the techdoc?

https://techdocs.shimano.com/media/te...9830612187.pdf

nwbikeman

It might be that you need to change the angle of the pads or you might have to change the spacers.The spacers I am talking about are between the arm and the pad is 1 set and then there is a set on the outside as well, or should be they come with the pads when replacing pads. If the inside spacer set is the wider pair( 2 silver washers) then swap them to the outside and the thinner pr. to the inside. Also you probably need to back off the spring tension of the brakes, both sides. The swaping of the washers has more to do with the rims width not pad angle but there should be plenty of adjustment for the pads to rim contact.

breadbin

well just as i was about to buy a pair of new xt v brakes, i decided to check the ones i have one more time. i popped them into the middle hole cos they were useless in the other one if the pads weren't hitting the rim. i didn't realise there were different noodles so swapped the one in it for a 90 degree one, think it helped. i did a bit of reading and seems some people bend the springs back to increase the tension too. i played with the screws at the side and they definitely make it better but they are nearly in all the way now as it is but at least it works for the time being. not sure why i didn't mess with them before. washers didn't make any difference though the pads still wouldn't go near the rim but its sorted for now

BCRider

Breadbin, the arms on V brakes need to be as vertical as practical for the pads to avoid hitting the highly flared out tires. Swapping the cup and ball washers around to let the arms stand as near to vertical as possible will hellp a lot.

For wider rims this often still isn't enough. In such cases you need to switch to something like Koolstop thinline pads which are overall thinner so they allow the arms to sit in a more vertical position.

The alternative is a parallel push style of V brake setup. Like the XT arms you almost bought. Or my favourite, the Avid Arch style of brake. Both of these will avoid the arc like up and out travel of the usual simple V brake setup where it can hit the flared out tire sidewall on a lot of MTB's.

breadbin

thanks bcrider, the rims are sun mammoths which are fairly fat by all accounts. the pads themselves are really thin, well compared to the xt ones i have on another bike they are tiny all the washers are swapped around to bring the pads closer and these brakes have the parallel push thing too so not sure why i had the bother in the other hole.

reptilezs

the spring tension holes have no effect of where the pad strikes the rim

BCRider

I agree that it SHOULDN'T. But I wonder if the angle of the parallel arm links are not set by the collar that has the pin in it as well as for setting the spring tension. Without seeing it in my hands it's hard to say. I haven't actually seen the LX parallel push arms in action. I went with the Avid Arch option and never looked anywhere else.