Bottom bracket wear - advice required

[flat-pack]

What is the way to tell if the bearings in bottom bracket need replacing ?

I cannot feel any grinding and there are no nasty noises but just feel the unit may need replacing, symptoms are a 'slackness' when climbing hills in between one pedal taking drive over from the other, difficult to explain but a sort of delay, drive is not smooth. Also able to move cranks slightly in towards the frame and away from it, about 4mm at pedal.

Bike is Giant Sedona coming up for 3 years old covered about 8K miles, bracket held in place with notched knurled ring, the kind you use a C spanner on ?

Can I tighten this up ?

Thanks in advance

Graham

 

[xpc316e]

Yes, you can tighten up this sort of bottom bracket, and it does sound as though there is too much free play from what you have said. There ought to be no free play in terms of moving the pedals in and out towards the frame. If I were you, I'd watch a few web-based tutorials and take it all out, clean it, regrease it, and put it all back together. This kind of BB will last for years if well-maintained.

 

[Gerry Attrick]

Check the crank to BB spindle security too.

 

[wbmkk]

Hi, I posted a similar problem 3 months ago, thinking my bike was beyond repair.

I eventually got a new bracket and the bike has been 100% better, and it was only £22 including fitting at my local bike shop.

I actually thought the thread had gone inside the frame housing, but it was actually the thread on the bracket that had gone.

Regards

 

[mickle]

To establish the condition of your BB bearing first of all unhook the chain from the chainset and tie it up out of the way.

Grab a crank and wiggle it side to side to see if there is any play. If there is it suggests that the bearing is worn or come loose.

Spin the cranks to see if it runs freely. If it doesn't spin nicely it suggests that the unit has suffered wear damage - a shattered ball or ball retainer cage, that the unit has allowed water in which has rusted the internals etc.

A quick way of assessing the state of it without opening it up is to spin it (keep the chain out of the way) whilst pressing your temple to the side of the seat - you'll hear any crunching reverberate through the bike.

 

[flat-pack]

Thanks all, will trust the bike to LBS sometime soon, do not have any tools and, if it comes out about £20, will probably have spent close to that on tools anyways.