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Bottom Bracket issues?!?
#1
Alright all, Noob question perhaps!

My bike is making a horrendous buzzing rattling noise when i put power through the pedals. I'm 95% sure it has nothing to do with the shifting/gears/chain as i had this set up professionally not so long ago and it doesn't make the noise when on a stand/upside down, pedaling through all the gears - they all shift fine too. Definitely not the chain rattling against the front mech.

The bike was bought mid November and is less than 100 miles old. The buzzing comes from around the bottom bracket area. And in the 3rd chain ring i can feel vibrations through the pedals. I've got a crank tool and have tried to tighten the cranks - they're as tight as they go without using excessive force.. I haven't removed them though.

Could this be a bottom bracket bearing issue? it started on my last ride and seemed to be getting progressively worse on my ride today. Its never been jet washed and its cleaned with hot water and a soft brush after (nearly) every ride.

I presume BBs are supposed to last longer than this, could it just be some sand/grit in there?

It was a mail order bike from Winstanleys in wigan - I've already had issues with the drive train not being set up at all correct out of the box, and am sort of losing patience with it a little.

Should i contact the shop, or take off the cranks and try to remove the BB myself and send it off for inspection?

Cheers for any advice.

Sam
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#2
Hi Sam
Bottom Brackets fitted to new bikes often aren't great. If it is the BB failing it will feel a bit crunchy in my experience...as crap has got past the seals and into the bearings.
What make are you cranks/chainset?
The easiest way to see if it is the BB is to remove the cranks and have a look and feel.
It could also be pedal related too.
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#3
in my experience a 'professional setup' doesnt count for s**t, i have had new bikes that have undergone a 'safety check and setup' and one so called service, all of which have involved me spending time putting everything right, so dont assume the bike shop did anything properly!

BB's dont tend to rattle though, its usually more of a creak or grind. Try giving the cranks a wiggle to feel if the bearings are loose. You say you 'tightened the cranks as tight as they would go', depending on the make this could be ok, or could prematurely ruin your BB.

Its very difficult to diagnose a bike by describing sounds on a forum, but the main point to note is that you bike is pretty new, therefore it is highly likely that some bolts have worked lose, this is to be fully expected, and is why most bike shops offer a free 'service' after 6 weeks or so.

So just go around the bike and check everything, all bolts...everywhere. Dont forget to check chain ring bolts and suspension pivots as well as shock mounts and mech hanger, wheel axles, basically anything that has the potential to move. Its then good practice to go around the bike every few weeks after you clean it and check this stuff regularly.

The chances are you will find the problem. You could check also the gap between the front mech and the chain as this can cause a 'rattle' (this gap can change as the frame flexes when you put power through the pedals)
If you dont find the problem then you could look at things like BB's. Worth asking if someone has a spare you can try rather than buying one, I have changed BB's before convinced that was the problem only to find it wasnt.
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#4
Id be surprised it its your bb, few bits of info will help

Does it make the noise in every gear or just specific ones

Are you running a chain device

External or internal bb ?

It's common for gears to be perfect in work stand with no resistance but need tweaking when riding, give us a few more details and we will try and help
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#5
Thanks very much for the replies guys. I appreciate its quite difficult to diagnose.

I've checked all the bolts I could see. I havent actually tightened the cranks - they were already as tight as i could get them. But tomorrow evening i'm definitely going to have another look over it, see if anything immediate jumps out.

Cranks/chainset and BB are all Alivio Octalink. mechs are Deore.

Its more of a buzzing than a rattle really. And its in every gear and only when pedaling properly (i.e not on a stand/upside down or when going downhill with not alot of power going through). This is why i think its not the gearing/shifting thats causing it. It definitely doesn't sound like the rattling i had when the front mech wasn't set up right. And it is the same noise regardless of the angle of the bike.

As for internal/external I've got no idea but a quick google says sealed bearings.

I'd take it into the shop across the road but tbh i'd rather do it myself and learn!

Cheers again,

Sam

PS - blackers that bridleway between them big steps and the church/primary school is horrendous at the minute. avoid! rest of oldbury route is dry though.
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#6
"Sammy" Wrote:Thanks very much for the replies guys. I appreciate its quite difficult to diagnose.

I've checked all the bolts I could see. I havent actually tightened the cranks - they were already as tight as i could get them. But tomorrow evening i'm definitely going to have another look over it, see if anything immediate jumps out.

Cranks/chainset and BB are all Alivio Octalink. mechs are Deore.

Its more of a buzzing than a rattle really. And its in every gear and only when pedaling properly (i.e not on a stand/upside down or when going downhill with not alot of power going through). This is why i think its not the gearing/shifting thats causing it. It definitely doesn't sound like the rattling i had when the front mech wasn't set up right. And it is the same noise regardless of the angle of the bike.

As for internal/external I've got no idea but a quick google says sealed bearings.

I'd take it into the shop across the road but tbh i'd rather do it myself and learn!

Cheers again,

Sam

PS - blackers that bridleway between them big steps and the church/primary school is horrendous at the minute. avoid! rest of oldbury route is dry though.

Well, Alivio is the cheapest of the cheap, so can't imagine the sealing is any good, so as its been I wiggle wet and muddy recently I would guess its the bb. Get a crank puller from Halfords and rip the cranks off and wiggle and turn the axle by hand. If it feels at all gritty and there is play, then its the BB. Not sure who makes octalink BB's any more so can't advise on a replacement without searching.
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#7
Cheers, yeah i've got a crank puller jobby. Just need to actually do it.

I know its cheap, but hey, its all i can afford. And the best of the bike is pretty good for the money i paid (£549)

What actually is "octalink"? And would I need an octalink BB to fit my cranks?

As its a new bike, would it worth contacting the shop re. warranty if it is fooked or is it just one of those things??
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#8
Where abouts are you fella... anywhere near Lordswood  Undecided
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#9
"Sammy" Wrote:PS - blackers that bridleway between them big steps and the church/primary school is horrendous at the minute. avoid! rest of oldbury route is dry though.

Big Grin Horses! I will have to start using the other route to get over that way.
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#10
What are you calling the 3rd Chainring.. big or small.. If small I would be tempted to say the front mech has twisted ever so slightly & the buzzing is the inner plate catching on the knobs to the tyre
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