I’m trying to replace the crank on my 2011 genesis core 10. So I purchased a fc m410 from CRC, after installing it I noticed that it sits too far out from the bb/chainline.

It came standard with what i think is a acera crank looks like fc m341-8. I’m not certain though. I also think my bb is a Shimano bb-es25 but again im not 100% sure.

How would I go about finding out what they are? I’ve tried spec sheet from suppliers but it just states “Shimano octalink”. Someone also mentioned that the fc m410 is far out from the bb because its more for roadie use, is that correct?

Thanks in advance.

How would I go about finding out what they are? I’ve tried spec sheet from suppliers but it just states “Shimano octalink”. Someone also mentioned that the fc m410 is far out from the bb because its more for roadie use, is that correct?

Nothing to do with road use – you need a new BB with a narrower axle, quite probably 113mm, although I’d check in the tech docs you have.

If it’s an option you may well be better to return the M410 and buy a Deore HT2, which includes BB, and negates all this trouble in future.

I was thinking the same, but I’ve been told id need the bb facing and by the time I do that and buy the part and bb tool its going to be a good £80. I wish I could!

I don’t think you’ll need to get the BB faced. In 8 years as I bike mechanic I only used the tool twice. That was on a old (badly) hand built frame. Just about any half decent frame these days has the BB threads by machine now and will be at 90 deg to the BB shell.

Looks like an fc m410 octalink crankset needs a 118mm long bottom bracket, I’m not sure about the fc m341 crankset but it might well be 126mm, which is why you are having your problems.

Best get the old BB old & check

http://techdocs.shimano.com/media/techdocs/content/cycle/SI/Alivio-Acera/SI_0094A/SI-0094A-001-ENG_v1_m56577569830667768.PDF

Thanks for the input!

Could anyone point me in the right direction too the correct chainset?

How do you know what length axle a chainset is suitable for? From what I’ve seen its just what bottom bracket they are suitable for but bb’s come in different axle lengths.

As I’ve said im pretty sure I have a es25-bb but looking at them on Various online retailers they seem to come in various axle lengths…

What point am i missing here?

Could anyone point me in the right direction too the correct chainset?

Bit difficult to do it that way round, you have a new fc m410 chainset that you probably can’t return if you have tried fitting it, so why don’t you just buy a new ES25 118mm BB ?

You will also need to check if your frame is 68 or 73mm wide at the bottom bracket – the best thing to do is to remove the old BB first before you do anything – I bet your bottom dollar that it is 126mm but don’t know what width frame the genesis’s are

cheers dicky boy, made me see sense..that’s what im going to do.

I’m sure it is 73mm width after measuring the bb. Where does it say that fc m410 needs a es25? On the tech sheet it says un26..but aren’t un26 square taper?

This is really doing my nut in..i thought it was going to be a relatively easy job, but its turned out to be a minefield of head ****!

I don’t have a bb tool arm. Need to get the cash out, I’m Hoping to order both bb and tool at the same time if i can, i need to get a bike fix asap, its been sat in my front room for like two months “trying” to get fixed.

Why can’t they make it simple..actually I don’t need a answer to that!

Right, after finding probably the only spec sheet on the web with a proper description for the bb it states…”Shimano es25 octalink 73-126″ so you could be bang on mate..8mm sounds about right for the gap that was left, the largest chainring was just outside the deraileur when in the highest gear.