What sized bottom bracket do i need? (numpty question)

[ED209]

I am now looking to upgrade my 2013 defy composites groups and I'm confused I think all road bike bottom brackets are the same but are they?

The spec on my bike just says - Shimano integrated , I am not sure what this means?

Will this fit?

Shimano Ultegra 6800 BBR60 Bottom Bracket - Black / English (BSA)


https://www.merlincycles.com/shimano-ultegra-6800-...

[upsidedownmark]

Not even close to the same!

There are two bits you need to solve - the internal diameter, and how it attaches to the frame. If you have shimano cranks in the current one, that's simple - 24mm shimano one. If you don't have shimano cranks currently, you may need something different.

The external part, more complicated. The one you link is for an english thread - external cups that thread onto the frame. If the one you have looks like this and you have shimano cranks, it's probably right http://www.wiggle.co.uk/shimano-bb-r60-ultegra-680...

However shimano integrated might mean pressfit, so no external cups and bearings pressed into the frame. That's more difficult and probably needs a bike shop to change..

[ED209]

upsidedownmark said:

Not even close to the same!

There are two bits you need to solve - the internal diameter, and how it attaches to the frame. If you have shimano cranks in the current one, that's simple - 24mm shimano one. If you don't have shimano cranks currently, you may need something different.

The external part, more complicated. The one you link is for an english thread - external cups that thread onto the frame. If the one you have looks like this and you have shimano cranks, it's probably right http://www.wiggle.co.uk/shimano-bb-r60-ultegra-680...

However shimano integrated might mean pressfit, so no external cups and bearings pressed into the frame. That's more difficult and probably needs a bike shop to change..

Yes i have shimano tiagara cranks.

[upsidedownmark]

In that case, fairly simple. If you have thread on external cups (which look like the ones I linked, though obviously you can't see the inside bits), then that 'english' threaded bb will do nicely (unless giant use italian threads, which I very much doubt. Look for 36 x 24 is the Italian thread and 1.37 x 24 is the english - written on the cups). If it doesn't have those obvious thread on cups, then you'd need to figure out what press-in type it takes, which is a can of worms. Best advice there would be if it ain't broke, don't fix it - if the bearings are OK, just put the new crankset in the existing BB. If you're replacing tiagra with ultegra it's a straight swap.

[bigdom]

Fairly confident you have a Shimano press fit bottom bracket, you'll either need some tools or off to LBS to have them replace it.

https://www.vanillabikes.com/products/shimano-sm-b...

[CoolC]

Google images of a defy looks like a press fit as suggested by bigdom.

[leyorkie]

If you are planning on changing it yourself then why not take it apart to see.
If it's push fit you will only have to remove the crank arm before you decide to go to the lbs
If it's a screw fit it will have the details on the various parts.
Order the right bits, job done.

[ED209]

leyorkie said:

If you are planning on changing it yourself then why not take it apart to see.
If it's push fit you will only have to remove the crank arm before you decide to go to the lbs
If it's a screw fit it will have the details on the various parts.
Order the right bits, job done.

I am planning on getting a bike servicer to do it but he can't get the groupset as cheap as joe public can buy it for online, seems crazy!

[upsidedownmark]

You don't need to take it apart to see if its press-fit. If it looks like that pic its pressfit, if it has big knurled bits between the crank and the bike its threaded.

Either way you can fit the groupset you linked, you just won't be able to use the BB if its pressfit. But the BB is about 15 quid, so I wouldn't worry.