Giant defy carbon. Bottom bracket creak

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peetee
Posts: 2798
Joined: 4 May 2010, 10:20pm
Location: Cornwall

Giant defy carbon. Bottom bracket creak

Postby peetee » 18 Apr 2018, 9:28am

I have just recently and successfully fitted a new press fit bottom bracket to a 2014 Giant Defy. This is a bike which features in many posts on online forums so hopefully my attempts will help a few others.
On the first attempt the bridging sleeve between the cups was damaged as it was very slightly miss-aligned. On the second attempt a new sleeve was taped to one of the cups and the cups pressed into place a couple of mm at a time, and the tool removed each time to check progress. So with a very carefully fitted bracket the bike was road tested a couple of miles and was creaking like crazy. The crankset was removed and the bracket press re applied. No inward movement was detected but nevertheless the bike was reassembled and road tested and is creak-free.
If you have a creaking bracket on any carbon bike, new or otherwise, its worth checking to ensure the thing went in right the first time.
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

Brucey
Posts: 42324
Joined: 4 Jan 2012, 6:25pm

Re: Giant defy carbon. Bottom bracket creak

Postby Brucey » 18 Apr 2018, 9:53pm

I think that sadly, it will only be a matter of time before said BB assy starts creaking again. LBSs near me routinely have to strip out the bearings in these bikes, smear a bit of grease (or bearing fit compound, depending on the fit quality) on the bearings and put it all back together again. It very rarely provides more than a temporary cure, that might last a few months, tops.

In fact in general terms, I think that press-fit BBs are a crap idea. Nobody I know (with formal engineering training or not) who has worked on bikes much thinks they are a good idea. It is all very well folks designing new bicycles with these things in, but one can only conclude that these folks must not actually ride real bikes in real weather; if they did they wouldn't inflict this rubbish on the general public.

It's not as if press-fit bearings are a new idea; folks have been using them in some cycle designs for at least a hundred years. In every previous incarnation press-fit BB bearings have ended up being unsuccessful, because they have caused more harm than good. I'm not sure that this time round things are much different tbh...

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

Valbrona
Posts: 2400
Joined: 7 Feb 2011, 4:49pm

Re: Giant defy carbon. Bottom bracket creak

Postby Valbrona » 19 Apr 2018, 4:09am

Whether BB cups or headset cups, always press in one fully and then the other, not both at same time.
I should coco.

peetee
Posts: 2798
Joined: 4 May 2010, 10:20pm
Location: Cornwall

Re: Giant defy carbon. Bottom bracket creak

Postby peetee » 19 Apr 2018, 10:49pm

I have to agree with you Brucey (although I will retain a bit of healthy hope). It seems madness to specify a interference fit component into a highly stressed area that, on this particular machine, is extraordinarily competent at resisting those stresses. Having test ridden the bike I was hugely impressed by its ability to transfer leg power to the tarmac. Dancing on the pedals puts forces in all sorts of less than ideal directions and those lowly nylon bb cups are expected to stay put. With a massive frame on one side and a substantial axle on the other they truly are, the weakest link.
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

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cyclemad
Posts: 180
Joined: 23 Jan 2018, 9:16pm

Re: Giant defy carbon. Bottom bracket creak

Postby cyclemad » 19 Apr 2018, 10:56pm

I was experiencing what I thought was a BB creak on my GiantDefy Carbon.....turned out to be loose Allen bolts securing the rear mech'. Check those first

hope it gets cured

Marcus Aurelius
Posts: 1665
Joined: 1 Feb 2018, 10:20am

Re: Giant defy carbon. Bottom bracket creak

Postby Marcus Aurelius » 20 Apr 2018, 9:53am

I’ve had creaks coming from, what I was certain was the B.B. and it’s turned out to be everything but the B.B. that was responsible. Q.R. skewers and the springs on the ends are a good source of creaks, so are the seat rails, and in at least one instance, it was the rim telling me it was about to fail catastrophically.

User avatar
cyclemad
Posts: 180
Joined: 23 Jan 2018, 9:16pm

Re: Giant defy carbon. Bottom bracket creak

Postby cyclemad » 20 Apr 2018, 11:20pm

I put a Fabric saddle on my giant.....CREAKED LIKE AN OLD DOOR....!!!!!