V-brakes

[Gummo]

I've just replaced the brakes on my Giant Escape 0 with Shimano Alivio BR-T4000s. They seem to be working well at the moment but I'm concerned that the wee pin on the brake only goes half-way into the middle hole of the boss(?). Can you foresee potential danger of the pin perishing early due to its shallow penetration?

Sorry if my terminology is inaccurate.

 

[si_c]

Sorry, not entirely sure what you mean, to avoid confusion/bad advice, would it be possible to post a picture and indicate what your concerned about?

 

[Gummo]

This isn't my photo but one with a similar arrangement:

 

[Big John]

That's a new one on me so I can't help much, I'm afraid. The bit that goes into the 'boss' is usually the end of the spring but the photo doesn't resemble anything I've seen before. It looks more like some sort of cable crimp that's too big to fit in the hole. I wait in eager anticipation for someone to turn up with a solution to the mystery.

 

[Gummo]

Here's another image I've found online:

 

[si_c]

I think it's one of two possibilities, firstly maybe you just didn't get the brake seated properly all the way, you are correct that it should be flush with the frame of the bike. Remove the bolt and the brake arm, add a little grease to the boss, and then try re-fitting, give it a hard push down whilst wiggling a little side to side, see if that helps.

The second, albeit remote possibility is that you have either non-standard bosses or the brakes are intended for non-standard bosses, when you take the brake arm off as above compare the inner diameter of the new brake and the old (I'm presuming you still have these to hand), they should be the same, just measure them with a ruler to make sure they match.

 

[Gummo]

I'm a bit more content tonight having taken off one of the brakes - the pin's about 66% of the way in. I've found the depth of the ridge (arrowed) is less than the depth of the replaced Tektro brake thus causing the whole issue.

 

[C R]

I'm a bit more content tonight having taken off one of the brakes - the pin's about 66% of the way in. I've found the depth of the ridge (arrowed) is less than the depth of the replaced Tektro brake thus causing the whole issue.

View attachment 664280

I had the same issue with the same model of brakes. The pins don't go in fully, in my case between fifty and seventy percent in. The bolt holds everything in place, and after four years in use haven't had an issue. Of course, YMMV.

 

[si_c]

Just a comment, as above, the pin doesn't actually retain the brake, that's the job of the bolt in the front, what the pin does is changes the basic level of spring tension, if you move the slot the pin is in you change the tension that the side springs are under so how quickly the brake returns to centred as well as having an impact on the position of the brake pads.

 

[Cycleops]

That certainly doesn’t look right in your original pic. The housing is not fully covering the spring, the post is still showing. I should try removing it and try to push the spring all the way into the housing. If you can’t then disassemble the entire thing and refit, although in your #7 post I can see that ridge is causing problems. If the housing is too far up the post the retaining bolt could contact it causing the brake arm to bind. Might be that it was designed to fit another standard of mounting post. If you want it correct you might have to ditch the Shimano and get another make. Sorry.

 

[Gummo]

I had the same issue with the same model of brakes. The pins don't go in fully, in my case between fifty and seventy percent in. The bolt holds everything in place, and after four years in use haven't had an issue. Of course, YMMV.

That's very reassuring - thanks.

 

[Gummo]

That certainly doesn’t look right in your original pic. The housing is not fully covering the spring, the post is still showing. I should try removing it and try to push the spring all the way into the housing. If you can’t then disassemble the entire thing and refit, although in your #7 post I can see that ridge is causing problems. If the housing is too far up the post the retaining bolt could contact it causing the brake arm to bind. Might be that it was designed to fit another standard of mounting post. If you want it correct you might have to ditch the Shimano and get another make. Sorry.

I will do if they fail - go back to the Tektro that lasted 8 years.

 

[Gummo]

Just a comment, as above, the pin doesn't actually retain the brake, that's the job of the bolt in the front, what the pin does is changes the basic level of spring tension, if you move the slot the pin is in you change the tension that the side springs are under so how quickly the brake returns to centred as well as having an impact on the position of the brake pads.

So, hopefully no threat to the pin.

 

[si_c]

So, hopefully no threat to the pin.

The pin shouldn't take any of the braking force, that's done by the wheel rim, the pin is there simply to provide a reference point if you will for the spring to push the pads away from the wheel when you release the brake lever. There is very little force put through it and it shouldn't be at risk of braking, although worst case scenario that does happen, you just need to replace the caliper and you'll have a binding brake until it's fixed so a bit more effort pedalling.

 

[Gummo]

The pin shouldn't take any of the braking force, that's done by the wheel rim, the pin is there simply to provide a reference point if you will for the spring to push the pads away from the wheel when you release the brake lever. There is very little force put through it and it shouldn't be at risk of braking, although worst case scenario that does happen, you just need to replace the caliper and you'll have a binding brake until it's fixed so a bit more effort pedalling.

Thanks very much for that reassurance.