Replacing Brompton spider crank set.

snazpizaz

Active Member
Location
London UK
Hi
I have a 2019 50T silver crank set i want to replace with a black one.

There's not much on the web or youtube about under-taking this myself but it looks relatively easy.
So a couple of questions:
1. Is changing the Brompton cranks set the same as changing any bike crank set and would i be okay following a generic bike manual ?
2. I know this video is 8 yrs old and the example isn't a spider crank, but if i followed it, would i be okay?

View: https://www.youtube.com/watch?v=hYo8Ta8SBxE&t=352s

3. I am a bit confused about the tools being used to unscrew the bottom bracket area / core - could someone explain the tools required and any sizes specific to the Brompton.

Thanks for your time folks
sp
 

Cycleops

Legendary Member
Location
Accra, Ghana
Should be the same. A socket for the crank bolt. You'll also need a crank extractor to remove the cranks, there are various types, this is from Halfords:

https://www.halfords.com/cycling/bike-maintenance/bike-tools/bikehut-professional-crank-extractor-164123.html

Plus a 15mm spanner to remove the pedals. Should all be very straightforward.
(Remember the LH crank has reverse thread, spanner should move to the back of the bike, both sides).
 
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Gunk

Veteran
Location
Oxford
They’re easy to get off, remove the bolts and then use a crank puller.

539846



If you are fitting a later “spider” crankset then you will need to change the bottom bracket, your one in the photo takes an ISO BB the replacement “spider” version needs a newer JIS BB.
 
OP
S

snazpizaz

Active Member
Location
London UK
Thanks -
1. My Brompton is a 2019 which came with a spider crank so the bottom bracket should be ok. (?)
2. Do i need to put the chain in a certain gear / on a certain cog ? I've got 6 speed standard with 2 cogs .
3. Do i need to grease the new black 50T cog - will 3-1 oil do or do i need something special ?
4. For the crank puller - do i need a specific size for the Brompton or will any generic one do / they all come in one size ?
cheers
sp
 
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