Yet Another Cycling Forum

General Category => Freewheeling => Folders => Topic started by: Aunt Maud on 02 June, 2019, 08:48:14 pm

Title: How do I check the Brompton rear triangle for excessive play ?
Post by: Aunt Maud on 02 June, 2019, 08:48:14 pm

I was going to say for play, but I thought it might give an excuse for .....you know, creative comments.

Anyway, how's it done and what am I looking for?

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: marcusjb on 03 June, 2019, 07:42:43 am

Pretty much unfold it and then grab the rear triangle and give it a good push and pull side to side.

Any play is time to address things.

https://brompton.zendesk.com/hc/en-us/articles/211950369-Rear-Hinge-Servicing

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: S2L on 03 June, 2019, 07:58:25 am

What kind of play are you talking about... there should be no side play at all... unless you mean play where the suspension bung is, in which case it doesn't matter as it will disappear once you sit on it

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: Jakob W on 03 June, 2019, 04:49:05 pm

I vaguely recall it's 2mm of play at the rear dropouts, but how exactly this is measured has never been entirely clear to me.

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: rogerzilla on 03 June, 2019, 09:04:38 pm

I heard a quarter of an inch, which is a lot.  At least, the bike is still supposed to be rideable like that. Derailleur versions may be more fussy, since you could get ghost shifts.

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: Aunt Maud on 06 June, 2019, 10:26:42 pm

Thanks for the replies. I thought it might be a grab it and wiggle it type thing.

So mine does 25 miles pre day 5 days a week. I guess I should take it in for a replacement after 8 months. Does that sound about right ?

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: LittleWheelsandBig on 06 June, 2019, 10:55:33 pm

Sounds pretty early to me but I have a fair tolerance of Brompton swingarm play and official Brompton advice back then allowed a significant amount (several millimetres, 2mm sounds about right but bromptonwiki has died) of movement. You check it by parking the bike (swingarm under) and measuring horizontal play at the dropout.

I think jsabine currently has my toolset for replacing the swingarm pivot but you are welcome to borrow it.

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: Aunt Maud on 11 June, 2019, 09:30:05 pm

Thanks LWaB, I'll check out what play there is and get back to you.

Title: Re: How do I check the Brompton rear triangle for excessive play ?
Post by: rogerzilla on 23 June, 2019, 09:00:43 pm

FWIW, I bought an old L3 many years ago that had seen 9 years' hard and fairly unloved commuting on and off a Surrey commuter train.  It was grimy and the paintwork was atrocious but the rear triangle was ok.  There was obvious slop but it ride fine.