I recently downsized the chainring on my 4sp T-Line from 56 to 50. What a difference. As a fairly fit and regular cyclist I was left wondering why the 56 comes as standard. As I use the bike to visit clients locally, I can now spin up the small local hills and not get too hot and sweaty. I can't pedal down the hills as much but that's fine. The purpose of the bike is transport and I prioritise comfort above top speed, because it's a Brompton!
I needed a couple of additional tools to complete the switch but it's all fairly straightforward if you watch the YouTube vid.
If you've been getting frustrated grinding up fairly modest hills, do it! It unlocks more of this amazing little bike's versatility 👌🏼
by Icy_Plan_329
5 Comments
now time for 5-speed conversion! 😎 u can have 21T low gear cog without any rub or grind, and nice gear jumps with 11,13,15,18 and 21T set. all u need is 11s cogs set, new 11s chain and 11/12s sram shifter with 1:1 pull ratio.
downside is 11s gearing is a little less durable than 10s due to thinner material and a bit higher cost to maintain. but wax can prolong the life of the chain when done correctly and religiously.
It’s now one of my essential recommendations to anyone buying a Brompton. I’ve similarly swapped my 6 speed C line from 50T to 44T to make longer hilly rides more doable. I don’t know why they come so high geared from the factory. If I’m spinning out now, I’m at a speed where I don’t really want to be going much faster on 16 inch wheels!
Because Bromptons were made primarily for city riding, probably London in particular. London is pretty flat so you ride on high gears pretty easily.
Same here. Went down to a 44 on a C2. I have walked up my last hill, I think.
I downsized mine from 44 to 39 with my 2×3 gears. Comford topspeed pedaling is about 25 kph.