Author Topic: Brompton cables rub on chain/ring  (Read 1535 times)

Brompton cables rub on chain/ring
« on: April 18, 2018, 11:35:19 pm »
I've noticed that the rear cables tend to rub on the chain at the front of the chainring, as they pass behind the ring. I know I have limited scope to re-route them without affecting the fold. I'm not even sure about using a cable tie to pull them towards the frame more. Has anyone found a good solution to this? I've tried just bending/flexing the housings, but they spring back over time.

Re: Brompton cables rub on chain/ring
« Reply #1 on: April 21, 2018, 11:30:47 am »
That's not a problem I've heard of before. Are they the correct length? Brompton cables need to be measured to the millimetre to sit right.

(this also makes using different brands with different stiffnesses potentially problematic)

Re: Brompton cables rub on chain/ring
« Reply #2 on: April 21, 2018, 01:36:11 pm »
Pretty sure they're the factory fitted ones. It's a very low mileage bike. It may be that repeated bending (flexing) will do it, or maybe I can put a cable tie round the retaining clip on the seat tube.

But there are so many Brompton parts and add-ons that thought it just possible that someone might suggest one. I'm aware of how critical cable length and routing are.

Re: Brompton cables rub on chain/ring
« Reply #3 on: April 21, 2018, 08:42:50 pm »
Well the other thing to check is that they put the correct ones on - Brompton production line quality control is not always great. They normally have a letter code embossed on the outer itself - e.g. FU+M for Front brake upper housing on an M type.

Re: Brompton cables rub on chain/ring
« Reply #4 on: April 22, 2018, 07:09:09 pm »
Now that's the kind of interesting snippet that you could only get here :)

Looks OK. I've got an FU+M (front brake), an L++M (rear brake), a G3+P (hub gear) and a GD+P (derailleur) on my P6R. What I did notice, on a second look, is that the four cables going to the back aren't in one bundle. The dynamo wire is tied to the derailleur cable, and it's those two that are flapping a bit towards the chain. I'll try just putting a fairly loose cable tie in to secure them to the other two. That will make a more rigid assembly that won't move from side to side so easily.

Kim

  • Timelord
Re: Brompton cables rub on chain/ring
« Reply #5 on: April 22, 2018, 08:34:04 pm »
I haven't commented up till now because my Brompton has neither standard cables nor standard chainset (my chainrings are significantly smaller, which probably helps to avoid rubbing issues), but since I had to work it all out from scratch, I ended up with an arrangement where the rear brake, gear cable and rear light cable were all cable-tied together as a single bundle from cable-gatherer to bottom bracket (using IIRC three cable-ties).  It works.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Brompton cables rub on chain/ring
« Reply #6 on: April 22, 2018, 08:45:40 pm »
Thanks, that's encouraging. I know from my late Dahon how easy it is for minor changes to affect the fold, and that point is made in large letters wherever Brompton document cable runs. I'm pretty sure that should solve it.

Kim

  • Timelord
Re: Brompton cables rub on chain/ring
« Reply #7 on: April 22, 2018, 08:54:46 pm »
Possibly obvious, but you want to arrange it so the tab on the cable tie(s) point towards the frame, so it doesn't snag on your leg.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Brompton cables rub on chain/ring
« Reply #8 on: April 22, 2018, 09:01:14 pm »
My legs thank you ;D