Brompton Crank Length

[mitchibob]

Thanks for the firm suspension tip. I think it's helped a bit, although still, once I hit about 95+ rpm, I really need to smooth out my pedalling in order to minimise the bounce.

I could go a little firmer on the suspension perhaps. Switching to firm hasn't really affected the ride much (just made my rear mudguard rattle like crazy). Certainly, my knees aren't hitting my chest, especially with M-bars, although maybe my belly after recovering from crash earlier in the year. Also, fact that frame is slightly bent after said crash is probably not helping, although that's mostly noticeable under braking.

One thing someone mentioned was that it wasn't wise to go too short on crank length, or the right crank wont fit nicely when folded.

First things first... try and maybe succumb to getting a 6-speed, and get this frame replaced. Can almost guarantee I wont get the dragons on as well the 2nd time. I wonder if I can get them to do that at the same time? It's a shame that with all the options Brompton give you when building a bike, crank length isn't one of them.

 

[mitchibob]

OK, so my 2-speed brommie definitely has a frame bending problem caused by a crash that didn't help. My new 6-speed doesn't have this problem, especially after fitting super-firm suspension. Now I can spin the pedals way faster without a hint of bouncing. Comfort might have been slightly compromised. I'll see how that goes on longer rides, but really upped my cadence for shorter ones.

However, while the bounce is gone, I'm still wondering about getting shorter cranks for my short legs, to improve comfort on longer stint. But, I'm wondering how short they can go without spoiling the fold?

 

[12boy]

If you want to firm up more without nubiles clips get a section of automotive rubber hose with a diameter inside that will allow you to work it over the bolt and an outside diameter that just fits inside the block. I think the block bulges both inside and out when compressed and that should work with minimum expense. I can't see that 165 cranks would affect the fold since 5 mm is 1/5 of an inch.glad you pretty much got things sorted out.

 

[12boy]

That was firm up with jubilee clips, not nubiles. Can't go there.

 

[Kell]

Or you could try the Joseph Kuosac block - I got one for mine and it eradicates all bobbing.

View: https://www.youtube.com/watch?v=BxeEln3X2qs

 

[mitchibob]

Or you could try the Joseph Kuosac block - I got one for mine and it eradicates all bobbing.

Got that already... got my cadence up a good 10-15%. No more bounce issues. Now it's to eradicate occasional hip issues.