Yet Another Cycling Forum

General Category => Freewheeling => Folders => Topic started by: Gattopardo on 04 October, 2017, 03:36:51 pm

Title: Brompton gearing and chain length
Post by: Gattopardo on 04 October, 2017, 03:36:51 pm

My brompton has a 3 speed Sturmey archer hub and was geared to 50 13.  The replacement crank is a 54. 

What rear cog would I need to keep the gearing similar and then the chain length.  Currently I have a 13, 14 and 15 toothed rear cog.

Title: Re: Brompton gearing and chain length
Post by: Diver300 on 04 October, 2017, 04:12:49 pm

54 - 14 is almost exactly the same gearing as 50 - 13

Title: Re: Brompton gearing and chain length
Post by: PaulF on 04 October, 2017, 04:12:55 pm

Unfortunately you can't have both the same gearing and the same chain length.

14.04T but they're pretty rare :-D to keep the same gearing so obviously the 14T or a 9T to keep the same chain length but they're even rarer.

Title: Re: Brompton gearing and chain length
Post by: Gattopardo on 04 October, 2017, 04:30:51 pm

(http://static.shoplightspeed.com/shops/608278/files/002758728/brompton-chain-1-2-x-3-32-100-link-plated-50t-6-sp.jpg)

This just confused me more will 102 be too long and 100 too short?

Also am running a 1/8th chain with a connector.

Title: Re: Brompton gearing and chain length
Post by: Pickled Onion on 04 October, 2017, 05:59:35 pm

102L will be absolutely fine with 54x14 (if that's what you're asking) since the table shows it will accommodate a two speed 54x12 - 54x16