Side pull single pivot brake centering - Brompton Traveller 5 speed with rack

[Blue Hills]

Hi chaps.

I have had my Brompton Traveller (5 speed sprinter gear, built-in rack and dynamo model) for about 15 years and have always been troubled by poor centering on the rear brake. But have lived with it and as I have not yet worn out the bike's initial brake blocks you can see that the bike hasn't done too many miles.

But it has become more of a problem - sometimes one side of the brake retracts so little when the brake lever is released that the block is touching the rim.

Can anyone tell me how to centre them?

Having looked at some generic stuff on side pull single pivot brakes I have the impression that a key bit that needs adjusting is a round bit of metal with flats which seems to interact with the spring.

But I can find no way of getting anything on to these flats as on this Brompton the long screw which mounts the brake onto the bike frame is also responsible for securing the mudguard and rack. And these, particularly the rack, get in the way.

Am I looking at the wrong bit?

If I'm not is there a way to adjust it?

 

[T4tomo]

I'd treat yourself to a new pair of caliper brakes, they are much better than the old ones fitted to your model. gte them fitted whilst your having the 5 speed hub looked at!

 

[Blue Hills]

I'd treat yourself to a new pair of caliper brakes, they are much better than the old ones fitted to your model. gte them fitted whilst your having the 5 speed hub looked at!

I was sort of hoping for a bit of advice rather than just chuck them

I do have a dual pivot rear brake I bought a few years ago for some reason but I may face the same adjustment question with that if fitted.

I know folk complain about brakes on the old Bromptons but in truth (and I wouldn't say that I'm an easy customer in general) I find mine OK performance wise.

I seem to remember that when I bought my Brompton in the late 90s folk were criticising the brakes on previous models.

So, anyone got any tips which don't involve hammering them with a credit card?

 

[shouldbeinbed]

I've had similar annoyingly fickle brakes on a road bike before, I'd manually move the blocks and calliper to a central position and then nip the tightness of the central bolt up a touch, it worked for a while but they always slipped out of kilter again.

Maybe disassemble and rebuild the rear caliper set up to be sure it's all properly clean and no niggly bits of grit worked their way in, gapping the blocks with spacers (lolly stick Ono) between them and the rim so you can't skew the alignment as you tighten it all up. Make sure you fit a new cable and outer to be sure that the limited use hasn't seen the cable corrode and be catching too.

I was always put off Bromptons largely because of the braking, it was ok but never THAT reassuring it'd work well enough when you really needed to stop. I test rode a 2013 model and nearly bought it on the spot, (I took possession of mine last November and it's been pretty much my daily ride ever since) they have improved the in-hand feel and stopping quite a bit IMO and certainly vs 15 y.o. calipers it may be worth thinking about replacing them.

 

[tyred]

Take the caliper apart and clean the pivot and lubricate with some light oil.

To centre it on the bike, there should ideally be some method of holding it in place, possibly requiring a very thin spanner behind the caliper arms next the brake bridge or a slot for screwdriver or a hex for a very small spanner/socket on the outside. Hold it central while tightening the mounting nut. A helper might be useful just to hold it. Make sure both arms are free to move as over-tightening them can also cause this problem but too loose will cause brake judder.

 

[Blue Hills]

Thanks for the replies so far folks but I really need someone with this model who can appreciate the potential issue with access to the brake.

 

[Brommyboy]

It is easy to centre the old side pull brakes: use a punch so that you can tap down on the spring that keeps them open. This will push the whole the other way. If you go too far, just use it on the other side to get them back. There is no doubt that the newer centre pull brakes are far superior, as I found out when I first updated mine!

 

[Blue Hills]

It is easy to centre the old side pull brakes: use a punch so that you can tap down on the spring that keeps them open. This will push the whole the other way. If you go too far, just use it on the other side to get them back. There is no doubt that the newer centre pull brakes are far superior, as I found out when I first updated mine!

aha brommyboy, many thanks.

I have heard of this hammer and a screwdriver system. I'd like to try it as an alternative to changing the brake*** (it's a real fiddle because the brake mount also holds a mass of stuff to do with the mudguard and the rack) but am somewhat wary, from experience, of letting myself loose with a hammer and screwdriver without more info. I had heard that the famed Richard Ballantine (he of the "shove your bike pump down an attacking dog's throat advice) advocated some similar system but on checking my copy of his Bicycle Book I could find no mention of it.

Do you by any chance have a link/link to vid or whatever with more info?

*** I did eventually (after reading Ballantine on similar brakes) notice that the dual pivot variant of the brake I have in the spares box has a small grommet which you can turn with an allen key to centre the brake though I wouldn't know how accessible this was until I had fitted it because of the aforementioned rack issue.

Hope to hear back from you Brommyboy - almost there I think.

On quality of the brakes for some strange reason I am actually pretty happy with the bike's stopping power.

 

[srw]

Take the caliper apart and clean the pivot and lubricate with some light oil.

This.

Again this is from memory, but it's relatively simple to get at the calliper. There's a single bolt which holds the brake to the frame (and IIRC also the mudguards and the rack). Just undo it, wiggle to get the brake assembly free, release the brake cable to free the calliper from that and the start taking the whole thing apart. Just make sure you put it back together again in the same order. While you're about it, replace the brake cables - inner at least, but probably both.

It sounds as if what you've got is gummed up brakes, which just centering won't solve. Again, I've had it both with my old 5-speed and my current 3-speed Bromptons, and in each case resolved it. And, I'll say again, I'm no techie.

 

[Brommyboy]

Blue Hills: As far as I know, there is no link to how to adjust the side pull brake. It is just what I was told to do by my very helpful cycle mechanic many years ago, and what I used to do on my 5-speed Brompton before fitting the dual pivot brake upgrade. I did say 'tap' and no damage can be done if you use common sense. All you are doing is rotating the whole brake assembly around its pivot.

 

[Blue Hills]

sorry brommyboy - I had the impression initially that this hitting/tapping of the spring was to "rebalance" in some way the way the spring acted on each arm. Your latest post seem to imply that it's just a way of applying pressure to rotate the brake assembly around its central pivot. I can do that with my hand. In fact it's this central pivot idea about these brakes that I fail to grasp. It seems such a bad idea. And every time I move the brake around this pivot, in time it just ends up moving back to the earlier unbalanced state.

As you can tell I'm trying to persevere with this brake (rather than fit the new one) at the mo to avoid taking all the rack/mudguard assembly out. I am also trying to avoid for the moment removing the back wheel (though I have done it many times before) as at the moment I am working on a gear shifting issue - and maybe getting somewhere on that front. I want to tackle one issue at a time/not introduce extra variables. And am happy with the braking.

Sorry to be a bore

 

[sidevalve]

I believe what you mean is tapping the spring to "centralise" it in it's recess in the pivot bolts [if it is too far over to one side it will had more "push" on that side]. One thing to be aware of is that the cable outer is not pressing [or "pulling"] on the brake assembly - it must be in a neutral position when the brake is off with the caliper in it's correct position. Be carefull that turning the bars doesn't cause it to creep along thus moving the caliper around.

 

[Brommyboy]

Blue Hills, in rotating the whole assembly by hand you achieve nothing beyond a temporary change. When you tap the spring in reality you are turning the cylindrical clamp that holds the centre of the spring tight, and this does work. Just try it and see if you then get a permanent centring. I have used that method effectively for all my older, side pull brakes.

 

[Brommyboy]

Blue Hills, in rotating the whole assembly by hand you achieve nothing beyond a temporary change. When you tap the spring in reality you are turning the cylindrical clamp that holds the centre of the spring tight, and this does work. Just try it and see if you then get a permanent centring. I have used that method effectively for all my older, side pull brakes.

 

[Blue Hills]

Many thanks brommyboy - got a big hammer yesterday, used it to hit a an old largish bolt (better than a screwdriver I think which has a sharp edge and may possibly damage) against a bit of the curly-section of spring on the appropriate side. After a few goes of delicate tapping (one not so delicate so I dislodged one side of the spring from its hook but managed to pop it back in) I managed it. All now seems well and if it should be an imperfect fix I am fairly confident that, now understanding more, I could fix it. It's the tight arrangement of the components on the Brompton that causes the issue, otherwise I could have just turned the flats on the spring-holding cylinder. In fact I think somewhere down the bottom of my toolbox is the Park Tool for doing that.

Thanks again brommyboy - you are a star