Giant Defy 4 BB

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richleeds
Posts: 38
Joined: Thu Aug 23, 2012 16:08 pm

Giant Defy 4 BB

Postby richleeds » Mon Oct 08, 2012 10:13 am

Hi - could someone assist? I would like to know what BB I would require to replace the Truvativ current drivegear to upgraded Shimano 105 5600 for my winter bike? Will I need some additional parts as I am unsure if it can accomodate the replacement gear. The Defy is 2009 modal.

getprg
Posts: 227
Joined: Fri Aug 21, 2009 22:04 pm

Re: Giant Defy 4 BB

Postby getprg » Mon Oct 08, 2012 11:01 am

You will need to check your existing crank/chainset but I'm pretty confident the original spec was Truvativ - in which case the chainset is a splined ISIS specification to match with a splined ISIS BB.

Shimano 105 5600 on the other hand will need a Shimano proprietary octalink splined BB - not expensive.

richleeds
Posts: 38
Joined: Thu Aug 23, 2012 16:08 pm

Re: Giant Defy 4 BB

Postby richleeds » Wed Oct 10, 2012 10:34 am

Thank 'getprg' - removal of the ISIS BB from the Defy 4 (2009) and replacing with Shimano I can use the Hollowtech II BB? Would I need any other parts? I am new to this and need guidance.

keef66
Posts: 8712
Joined: Tue Apr 29, 2008 09:46 am

Re: Giant Defy 4 BB

Postby keef66 » Wed Oct 10, 2012 12:39 pm

If you're replacing the existing BB and chainset with the Shimano BB and chainset all you'll need are the tools to remove the first and to install the second.

Can't help with the Truvativ stuff but all you need to install Shimano HT2 stuff is the BB tool and a big spanner or socket to tighten it, the little plastic thing to tighten the plastic preload cap, and an allen key to tighten the little pinch bolts on the non drive side crank.

richleeds
Posts: 38
Joined: Thu Aug 23, 2012 16:08 pm

Re: Giant Defy 4 BB

Postby richleeds » Wed Oct 10, 2012 13:24 pm

Thanks keef66 - my Defy 4 winter bike looks like a smaller BB than the Shimano BB that I will replace it with. My concern, will it fit as the Shimano BB is external and Truvativ looks like an internal BB?

keef66
Posts: 8712
Joined: Tue Apr 29, 2008 09:46 am

Re: Giant Defy 4 BB

Postby keef66 » Wed Oct 10, 2012 13:43 pm

Yep, the bottom bracket shell is threaded internally. The older cartridge type BB's sit completely inside the BB shell and just the axle ends protrude. In contrast the external type BB cups still screw into the same threads but the bearings sit outside the BB shell and the axle (which is attached to the crankset) is pushed through them and secured by attaching the non drive side crank.

richleeds
Posts: 38
Joined: Thu Aug 23, 2012 16:08 pm

Re: Giant Defy 4 BB

Postby richleeds » Wed Oct 10, 2012 14:36 pm

Thanks keef66 - last Q; will I need any spacers for a Shim 105 5600 chainset?

keef66
Posts: 8712
Joined: Tue Apr 29, 2008 09:46 am

Re: Giant Defy 4 BB

Postby keef66 » Wed Oct 10, 2012 15:58 pm

No spacers required for Hollowtech II road double cranksets

Triples have one each side


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