Adjusting single pivot brakes

[Frank9755]

I haven't had a bike with these since the 70s, and I didn't do much maintenance then, but I am now trying to adjust some for someone else.

What I keep finding is that the arm on the side where the cable goes doesn't seem to spring back, it just stays with block against the rim. 

My instinct is to bend the spring on that side to give it more power.  Is that the best approach, or is there another technique?

[rogerzilla]

No.

1. Ensure it's not the length of the cable outer causing the brake to dip on one side.
2. Lubricate, including where the springs slide on the arms.  Consider fitting Shimano nylon spring sleeves at these points.
3. Loosen the backnut and centre the brake properly.
4. As a last resort, tap the spring on the side furthest from the rim using a drift and a Brummagem screwdriver.

[drossall]

Also check the two locking nuts on the "front" of the pivot bolt. Make sure that there's no play, but free movement.

I generally found them not too bad, though the quality of the brake had a big effect on how easy it was to adjust. What brand? Later Weinmann designs had a hex post on the pivot that took a special tool, which is still in my box. Only relevant for that design though.

[Somnolent]

When adequate quality Tektro dual-pivots (with old-skool nut fitting) are available for around £30/pair (R359 / R369 at Spa for example) I tend not to bother trying to sort inferior single-pivots.  Given that the average punter would spend more than that just to take a bike in to Halfrauds for a cursory look and a sharp intake of breath from a pimply youth, I'd say that unless the bike is something really special you'll both end up happier going down the replacement route.

[Frank9755]

Yes, it's someone else's bike they've asked me to have a look at.  I'm tempted just to buy a new brake as I'd rather not spend time learning how to fix an obsolete brake.  However, it does look like a very long drop.  I actually had a Tektro R369 sitting on the shelf (a rear one, no idea where the front has gone) and it seems not to be deep enough.

[LittleWheelsandBig]

Do you want me to have a look at it for you? PM if so.

[Frank9755]

Do you want me to have a look at it for you? PM if so.

Thanks for the offer, very kind of you.
I'll have another go but may take you up, when it's not quite so wild outside!

[Frank9755]

I think I've got it..
really it needs replaced but should do for now.

[hubner]

Adjust the brakes so they're off centre. When you apply the brakes, they will open up centred.

[mzjo]

Need a star washer between brake and fork to stop the bolt twisting (it doesn't have to move much to throw things out). I am sure that most, if not all my Shimano sp brakes have such a washer.

If it's a long drop the dp Tekro that you want is 559 (I use them on two old race frames converted to 650b) but forget that if you need nutted brakes. The set that I bought in the last year cost me 50€ from a seller in Taiwan. At the last search he was the only source, all the others sold out, and they were 100€ the pair for the last two in stock! I think the sunken head sort are still available, probably at SJS. I think there may be a Shimano deep caliper brake but not as deep as the 559.

[drossall]

SJS also do a convertor bolt.

[mzjo]

SJS also do a convertor bolt.

Although reading the comments on the site is useful and informative. It doesn't work on R559! (Expletives and other anglo-saxon words deleted!)