Author Topic: Brompton 2 speed nightmare  (Read 4836 times)

Brompton 2 speed nightmare
« on: 23 June, 2011, 09:48:07 am »
Hi,

I've had my S2L for about 8 months, used most days for 2 miles to the station, 0.5 miles to the office.

In the last couple of months the 2 speed derailleur has become reluctant to move to the easy gear. I've adjusted the limits and moved the cable down in the shifter, but about 1 times in 5 I push the shifter and the chain is just rattliing against the outer sprocket.

Is there anything else I can do?

Thanks,

John

LittleWheelsandBig

  • Whimsy Rider
Re: Brompton 2 speed nightmare
« Reply #1 on: 23 June, 2011, 09:57:00 am »
Lubricated the cable?
Wheel meet again, don't know where, don't know when...

Arellcat

  • Velonautte
Re: Brompton 2 speed nightmare
« Reply #2 on: 23 June, 2011, 08:43:31 pm »
It's probably not the adjustment of the chain 'pusher', and in my experience the cable should still be ok at that age.  If it's going to be grotty, it'll most likely be at the wheel end where the spring loaded section is.  But the gear lever moves more cable than the derailleur actually uses, so the bum shifting often occurs as a result of something else.

Do check the two jockey wheels of the chain tensioner, especially the upper one.  They rotate and slide on stainless steel bushings which are fairly well sealed from the elements but the clearance between the jockey wheels and the carrier is quite small and gets gunged up.  Despite (and probably because of) feeding teflon lube into the narrow gap on a regular basis, the shifting on mine became absolutely appalling.  I eventually had to take it all apart, washed the components, and then treated the bushings to generous amounts of Castrol Moly Grease.  So far, so good!
Quote from: Morningsider
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Re: Brompton 2 speed nightmare
« Reply #3 on: 24 June, 2011, 09:24:39 am »
I gave in and took it to the shop where I bought it, they've rung to say they've fixed it, so I'll be interested to see if they have!

For future refeerence, how did you take the derailleur apart? Are there some instructions somewhere?

Thanks,

John

LittleWheelsandBig

  • Whimsy Rider
Re: Brompton 2 speed nightmare
« Reply #4 on: 24 June, 2011, 09:43:05 am »
There are a couple of plastic push-in caps in the ends of the jockey pulleys that are easily removed. After that, it is quite straightforward to dismantle and clean the derailleur.
Wheel meet again, don't know where, don't know when...

Re: Brompton 2 speed nightmare
« Reply #5 on: 12 January, 2012, 05:42:32 am »
Newbie... 1st post...  I had the same problem with my 2008 M6R recently acquired off eBay... The jockey wheel was barely making contact - and only on one side of the chain pusher.  After 3 hours on my stand, and everything taken apart I could not figure out how to seat the jockey wheel any closer to the chain pusher. My local Brommie shop unbolted the the chain tensioner and found the wheel retainer clip was deformed (likely from the previous owner cranking the bolt over the improperly seated retaining clip, and flattening it out). We simply flipped the U-shaped retaining clip over to the unused side, and it made enough space for the whole jockey wheel assembly to sit right where it is supposed to. Problem fixed!

Side note: the Brompton youtube video recommends tightening the wheel bolt slightly tighter than "hand-tight", but I found that my bolt had worked itself loose - from being installed (overtightened at that - according to Andrew Finkell) the night before... What gives?  How tight is that bolt supposed to be (in light of the retaining clips - intended to prevent the wheel from falling off the bike)?

Regards,

  Allan