Question about adjusting v-brakes

Barney74

I've just adjusted the v-brakes on my old mountain bike, and while I've managed to get the front one nice and tight, I can't do the same for the back one. The pads are positioned correctly but the rear brake feels really spongy when I pull on the brake lever and when released there's clearly some slack in the cable. I'm tugging with all my might to make the cable more taut, but it's hard to do this and clamp the brake arm on to the cable in the right place at the same time. Is there a trick to doing this? In an ideal world I'd have somebody helping me, but unfortunately I don't have the option. Perhaps I should be using a clamp or something? The bike is an old one so I don't have the option of using discs.

supersonic

Check the smoothness of the cables first. Also pulling it tight sometimes moves the outer cable out of the brake lever a little.

You can buy third hand tools to clamp them together, but there is a technique... or try this. Wind the barrel adjuster out as far as it will go. Do the cable up as you have been doing, then wind the barrel back in again!

Also check the spring tension of the v brake arms, it may be really slack. There is usually a screw to adjust them.

stumpyjon

Might be a daft suggestion but are your seat stays bending when you are pulling the rear brake. I swapped from Magura hydraulic rim brakes ages ago on my hardtail to LX V brakes and the back one always felt spongy. Tracked it down to the seat stays bending (the Maguras had an integral stiffener in their setup). Ended up getting a horsehoe thing that stops this happening.

If it is cable related, one way of setting it up is to hold the blocks tight to the rim and then partly tighten the cable screw. Then apply the lever very gently to pull a small amount of cable through to get the adjustment right and tighten the screw fully.

Sonic's methods are probably better though .

ride_whenever

Are you sure it is not cable stretch, I find that the rear one is always more spongy than the front purely because of the extra length of cable. If I do get it nice and firm then I can't get the brakes undone without undoing the cable first.

Barney74

Thanks for the advice. I'll give it a go. The brake cable is brand new, so it shouldn't be stretching more than is normal.

chilledsandwich

A cable will always stretch a bit when it is new. You will probably find that even if you get your brakes set up amazingly to begin with, after a bit of use you will need to readjust them to compensate for cable stretch. This is annoying but normal.

Set-up wise, I do now have a third hand tool which is great for the brakes and gears, but I used to use Supersonics barrel adjuster method and that always worked fine for me!! Good luck!!