Help : Crank\Chainring Issue

Mechanical Problems and Product Reviews.

Moderators: Crooch, billstup, Super Moderators

Help : Crank\Chainring Issue

Postby Gofster » 03 Jul 2015, 07:55

Hi

I have put some smaller length cranks on my sons bike, however the spider on the cranks is not cupped as deep. Therefore this has caused the chainring to not run true with the freewheel.

I was thinking of putting some spacers between the spider and chainnring to move it closer to the frame and was wondering if anyone has done this before or if someone had a better idea.

Thanks

Andy
Gofster
 
Posts: 28
Joined: 21 Jan 2014, 13:42

Re: Help : Crank\Chainring Issue

Postby bigpimp347 » 03 Jul 2015, 08:04

on some spiders you put the chainring the other side of the spider inside or outside,
if it doesn't run true either way then you can use a spacer (i assume these are three piece types and not BMX designed)
i used a spacer on some old Tioga BMX cranks and worked ok,

on external bearing types (hollowtech types) they come with spacers to move the bearings in and out (make from 68mm to 73mm) but sometimes to line up you do without one spacer and have to add another to get the right chain line.

what's worse is if you have OCD trying to get the ledal arms to be the same distance from the frame on the trailing arms.!!

further not, is the wheel a cassette type or sprocket ??
if cassette can you not put a spacer where the gear is to move it further out ??
bigpimp347
 
Posts: 569
Joined: 09 May 2014, 23:02

Re: Help : Crank\Chainring Issue

Postby Gofster » 03 Jul 2015, 08:18

Hi

Yes it is a 3 piece crank but on a square type cartridge bottom bracket, but I might try your other option first as it has a cassette type on the back wheel as I didn't know you can change the spacing behind that.

So many thanks for that option

Thanks

Andy
Gofster
 
Posts: 28
Joined: 21 Jan 2014, 13:42

Re: Help : Crank\Chainring Issue

Postby bigpimp347 » 03 Jul 2015, 16:03

with it being a square taper type BB i assume 110mm you try a 113, or even 118mm perhaps to bring the arms out further that way as you can't space them very well on the BB
i though had a three piece with the 19mm axle type,
on the rear cassette type you can get a spacer ring about 1mm or 1.5mm or such so might work that way too.
bigpimp347
 
Posts: 569
Joined: 09 May 2014, 23:02

Re: Help : Crank\Chainring Issue

Postby HEYWOOD BMX » 23 Jul 2015, 13:45

:D The spacers that fit an external/outboard BB are the same size as those for cassette hubs and also the same size as the threaded part of a freewheel hub (16t upwards) so can be used to space out a freewheel too.
User avatar
HEYWOOD BMX
 
Posts: 513
Joined: 18 Sep 2007, 08:48
Location: HEYWOOD


Return to Technical Help

Who is online

Users browsing this forum: No registered users and 2 guests