Bottom Bracket Size???

[Funtboy]

Hello masters of the board,

I need to replace my bottom bracket (or get LBS to do it) and I don't know what size it is. I know it is octalink.

Here is the 'geometry' of my bike...

http://www.fisherbikes.com/bike/archivemodel/323

I was rather hoping I could get this for a fiver...

http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=34653

This seems like a daft question but will it fit?


Many thanks in advance...

 

[MajorMantra]

Measure the width of your bottom bracket shell (it will be 68 or 73mm) and then either measure the axle, or check the Shimano tech documents (on their website) for your chainset to make sure you get the right axle length.

Matthew

 

[MajorMantra]

(And yes, one of those should fit, but possibly not the £5 one.)

 

[Funtboy]

Cheers Mate,

It appears to be 73mm

Not sure how to measure the axel...

 

[Funtboy]

Nah, I'm stumped!

 

[redjedi]

take out the bottom bracket. It should have the measurements on a sticker if it's still on there and readable.

If you can't read it take it to a LBS and ask for the same one, but then you may not get it for a fiver.

 

[Funtboy]

take out the bottom bracket. It should have the measurements on a sticker if it's still on there and readable.

If you can't read it take it to a LBS and ask for the same one, but then you may not get it for a fiver.

I had thought of that. I don't have the tools to get it out though. I was hoping to deduce the size, buy it on the net and then take it to the LBS to install it.

 

[TheDoctor]

Can you get the cranks off? If so, poke something through the axle (it's hollow) and use that to measure the axle length.
I will point out that the tools to get a sealed BB out will probably be cheaper than getting the LBS to do it for you - this will get the BB out and this will get the cranks off.

 

[MajorMantra]

Can you get the cranks off? If so, poke something through the axle (it's hollow) and use that to measure the axle length.
I will point out that the tools to get a sealed BB out will probably be cheaper than getting the LBS to do it for you - this will get the BB out and this will get the cranks off.

This is good advice. Just make sure you remove any washers before inserting the crank puller. Also, note that you need to own a socket spanner to use that puller.

As I said above, you may be able to deduce the correct axle length from the Shimano tech info.

Matthew

 

[Funtboy]

Can you get the cranks off? If so, poke something through the axle (it's hollow) and use that to measure the axle length.
I will point out that the tools to get a sealed BB out will probably be cheaper than getting the LBS to do it for you - this will get the BB out and this will get the cranks off.

Great stuff. Many thanks...

 

[Funtboy]

This is good advice. Just make sure you remove any washers before inserting the crank puller. Also, note that you need to own a socket spanner to use that puller.

As I said above, you may be able to deduce the correct axle length from the Shimano tech info.

Matthew

Thanks to you as well Matthew. I tried the shimano site but it was beyond my ken. Knowing that I had a 73mm octalink BB didn't seem to help me. I suspect you're not as stupid as me.

 

[MajorMantra]

Thanks to you as well Matthew. I tried the shimano site but it was beyond my ken. Knowing that I had a 73mm octalink BB didn't seem to help me. I suspect you're not as stupid as me.

Actually I've just had a look at the site and the relevant bit is so badly organised that I couldn't find anything useful either. If you knew the exact model of your chainset you might be able to figure it out, but to be honest just measuring the thing is probably easier!

Matthew

 

[Funtboy]

Actually I've just had a look at the site and the relevant bit is so badly organised that I couldn't find anything useful either. If you knew the exact model of your chainset you might be able to figure it out, but to be honest just measuring the thing is probably easier!

Matthew

I have to get it out to measure it though and it's a toss up between buying the tools and giving it to the LBS.

Hmmmmmm.

 

[4F]

Buy the tools and do it yourself. I did it myself for the first time last year and it was a doddle

also check this site out http://bicycletutor.com/

http://bicycletutor.com/cartridge-bottom-bracket/

 

[MajorMantra]

I have to get it out to measure it though and it's a toss up between buying the tools and giving it to the LBS.

Hmmmmmm.

You don't have to actually remove the BB to measure it if you use the method above (stick something though the hollow axle) but you do have to remove the cranks. Taking cranks off is easy though and if you're in doubt there are a slew of tutorials (biketutor etc.) online.

Matthew