Chainset bottom bracket compatibility

[mnichols]

I'm considering replacing my chainset as the current one is very scratched has tens of thousands of miles on it and they are currently on offer, but I'm not sure what I need to order

The current chainset is a 105 triple (50 outer ring) and I want to replace it with the new 105 triple but I'm not sure if the new one will be compatable with the bottom bracket on my enigma etape. The only markings I can find on the bb are BC 1.37 x 24 but I'm not sure what this means

http://www.wiggle.co.uk/shimano-105-570 ... 1&curr=GBP

[Brucey]

there will be a model number on the cranks themselves; this is what you need to find.

cheers

[tim-b]

Hi

The figures that you've quoted are the thread type for your BB (1.37 x 24 is British when you come to order). The link that you supplied doesn't make it clear whether a BB is included or not

Current Shimano cranksets and BBs are interchangeable, you can put an Ultegra BB with Tiagra cranks for example because the BB is just a set of bearings and cups. The axle is permanently attached to one crank

As suggested, find the model number, also make sure that you choose the same number of "speeds", e.g. 10s, and the correct crank length. Markings on your existing cranks will tell you all of that

IME front mechs are a pain so check that the mech can handle the new chainrings if they differ from the existing tooth numbers. This might extend to the rear mech and chain length too

Regards
tim-b

[foxyrider]

Just buy a new BB, they cost very little and then you've no worries

[Wheelscymru]

Woulf suggest removing old chainset and bottom bracket, this would give you the information you need regarding length of axle plus quality of said BB. I would be looking for chainset plus bottom bracket included myself tomake it simple. This is assuming of course this is what you intend to do. If teeth on chainrings are worn then this is sensible option but as another contributor pointed out, usually one just replaces the BB. As stated the info you need is stamped on this and visible when removed. The make and quality of the replacement is your choice and not necessarily to follow original make i.e. (Shimano).

[mnichols]

If my front mech (105) works with current 105 triple is it safe to assume that it will work with new one given that they are both for 10 speed rear?

So I need to take bb out to get all the info?

[recordacefromnew]

So I need to take bb out to get all the info?

No, you just need to read the FC-xxxx code on the inside face of a crank arm.

[tim-b]

Hi

I don't think that you need to change the BB if it's smooth and free of play. The new cranks should slip straight in, but I wouldn't like to be definitive because I'm not familiar with every version of 105. I think that the 10s models are FC5603 and FC5703

BB axle length doesn't come into it. The BB axle is part of the driveside crank, provided you swap one road triple 105 with another, all should be fine

Crank length and chainring tooth numbers are likely to be the greater problem (as mentioned above), unless they're the same of course

Regards
tim-b

[freeflow]

Given that you say you have tens of thousands of miles on your chainset it might be worth checking which version you have at the shimano technical documents page for 105 components

http://si.shimano.com/#seriesList/18

When you look at this page you will see why people have been asking you for your model number.

If your model number is 5803, 5703, or 5603 then you can reuse you BB. If your chainset is 5503 or earlier then your BB is not compatible with the Hollowtech II BB system. Hence you will need to also get a hollowtech II BB if it is not supplied with the chainset you have linked to.

If your BB and cranks are OK then you could just consider replacing the chainrings.

[cycleruk]

Is your old crankset the same as the one from Wiggle?
If so then the new one will just slide into your existing BB.
If it's not the same then you will need a "hollowtech 2" type BB.
This is the BB:-
http://www.merlincycles.com/shimano-105 ... 49200.html

Sometimes the BB comes with the crankset but the wiggle advert doesn't say Yay or Nay.

The crankset comes with thin spacers which are used to set the width. There should be an instruction leaflet with it showing how.