Alt Cranks for Bromptom
02-28-17, 01:54 PM
#3
Part-time epistemologist
For specific question like this, I'd talk to the folks at Brompton Talk.
I remember this old post with a similar question.
https://www.bikeforums.net/folding-bi...-thread-2.html
I remember this old post with a similar question.
https://www.bikeforums.net/folding-bi...-thread-2.html
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02-28-17, 02:41 PM
#4
Banned
Lots of S bend cranks wil actually increase the Q some..
Blogging in the past, Todd, a partner at Clever Cycles in PDX put a double crank on before doing a Tour down the coast on his M6L.. still used square taper BB.
I put a Schlumpf Mountain drive crank on my M3L. Another option the Speed drive 34t, gives you the 54t in overdrive.. BB is part of the Crank.
Chain does not shift, the cranks just turn at a different rate than the chainring does.
...
Blogging in the past, Todd, a partner at Clever Cycles in PDX put a double crank on before doing a Tour down the coast on his M6L.. still used square taper BB.
I put a Schlumpf Mountain drive crank on my M3L. Another option the Speed drive 34t, gives you the 54t in overdrive.. BB is part of the Crank.
Chain does not shift, the cranks just turn at a different rate than the chainring does.
...
03-01-17, 10:24 AM
#5
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I have used several external bearing road cranksets with Bromptons and q-factor has always been an issue. External bearing cranksets can certainly be mounted however. This is why it is better to use square taper or ISIS bottom brackets as they have different bottom bracket options for wider clearance.
03-01-17, 09:00 PM
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03-05-17, 08:35 PM
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Alt Cranks for Brompton
Perhaps MTB cranks would be better. I find for my riding a 44T ring on the Brompton is preferred. I'd like to reduce the weight and I thought modern cranks may drop 1/2Lbs.
I have used several external bearing road cranksets with Bromptons and q-factor has always been an issue. External bearing cranksets can certainly be mounted however. This is why it is better to use square taper or ISIS bottom brackets as they have different bottom bracket options for wider clearance.
03-05-17, 08:55 PM
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I don't see why not. I 'm running a 172.5 FSA Gossamer crank, BB386 with no issues. Based on my experience
you will probably have to add a 1.5-2 mm spacer to the right side BB cup. Your looking to get clearance in the folded possition.
you will probably have to add a 1.5-2 mm spacer to the right side BB cup. Your looking to get clearance in the folded possition.
03-06-17, 03:29 AM
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Again, check the q-factor if you plan on using an external bearing crankset. You cannot just use bottom bracket spacers to space out the crankarms because the bottom bracket threads won't be long enough for anything more than 1mm.
A MTB crankset would give more clearance but you'd be stuck with smaller chainrings. Standard Brompton chainrings are 44t, 50t, and 54t so you'd be limited to the lower-geared end as you mentioned.
A MTB crankset would give more clearance but you'd be stuck with smaller chainrings. Standard Brompton chainrings are 44t, 50t, and 54t so you'd be limited to the lower-geared end as you mentioned.
Last edited by leoho5; 03-06-17 at 03:40 AM.
