Movement in crankshaft - help!

[Toby_2009]

Hi,

Noticed yesterday that there is a very small amount of movement (3 mm maybe) in the across the crankshafts, i.e. if you wiggle one from the pedal end then there is movement in tho other one two, although its only a small amount of movement, on a long ride it gets pretty annoying!

The cranks are held on with a 8mm hex key thing which I have tried tightening but its as tight as it will go.

I will take it to the shop tomorrow (gotta get a spare inner tube anyway) but just to save myself the shame if its ridiculously simple, does anybody have any ideas?

Cheers,

Toby

 

[marinyork]

Movement in which direction? Could be broken BB?

 

[Toby_2009]

Movement in which direction? Could be broken BB?

the movement is in the same direction as the handle bars (side to side that is)

is that BB being ball bearing, if so what sort of cost we looking at?

Cheers,

Toby

 

[Toby_2009]

oh and should have mentioned, its a GIANT Boulder MTB- about 6 months old and had a pretty low mileage until the last month (movement has started in the last week)

 

[marinyork]

I am no expert believe me but when you say side to side movement by that amount that's what springs straigh away to my mind. BB is bottom bracket and it'll be £20-30 if it is that. It could need tightening though, who knows.

 

[Toby_2009]

I am no expert believe me but when you say side to side movement by that amount that's what springs straigh away to my mind. BB is bottom bracket and it'll be £20-30 if it is that. It could need tightening though, who knows.

sorry, im a newbie, what is the bottom bracket?

 

[zimzum42]

It's the bit between the two cranks, it's an axle with two sets of bearings.

Might have been badly fitted, but more likely to be a shoot BB, so just replace it. Get a cartridge one, should be 20-30 squids. Make sure the shop that fits it knows that they have to fit it properly, it's not a big job, watch them do it!

 

[Toby_2009]

It's the bit between the two cranks, it's an axle with two sets of bearings.

Might have been badly fitted, but more likely to be a shoot BB, so just replace it. Get a cartridge one, should be 20-30 squids. Make sure the shop that fits it knows that they have to fit it properly, it's not a big job, watch them do it!

ok, so how will I know if they put a decent one in?

The thing is that becuase im only 16 they treat me like they do the rest of the kids, think its just a to school and back bike and assume i dont know what im talking about and if i ask that sort of thing then they seem to think im telling them how to do their job.

just typing that makes it sem like i should use a dfferen LBS, maybe il try the other local one, bit of a representation of being expensive tho.

 

[zimzum42]

Ask for this:
http://www.parker-international.co.uk/2481/Shimano-UN72-Bottom-Bracket.html

It's pretty decent. Using the phrase 'cartridge bottom bracket' should show them you know a little, and asking them to make sure if the thread on your bottom bracket shell is English or Italian ill leave them speechless (maybe)

Maybe ask about local clubs and stuff to show you're a bit more serious

Don't be afraid of going to the other LBS, nor buying the part cheap and paying another place to fit it if you're really upset with them

 

[marinyork]

LBSs are like that whatever age you are. Anyway I don't know about the components in that but I can imagine the BB breaking the sort of speeds you're doing on the MTB if it's a cheap one. I'm sure there are alternative shops?

 

[Toby_2009]

Ask for this:
http://www.parker-international.co.uk/2481/Shimano-UN72-Bottom-Bracket.html

It's pretty decent. Using the phrase 'cartridge bottom bracket' should show them you know a little, and asking them to make sure if the thread on your bottom bracket shell is English or Italian ill leave them speechless (maybe)

Maybe ask about local clubs and stuff to show you're a bit more serious

Don't be afraid of going to the other LBS, nor buying the part cheap and paying another place to fit it if you're really upset with them

cheers, thats really useful, thanks, could you just explain the italian/english thing for me please

 

[zimzum42]

thought you might ask that!

The bottom bracket fits into the frame, the bit it fits into is called the bottom bracket shell. It screws in, so the shell has a thread. With an Italian thread it screws in one way, with the English it screws in the other way (don't ask me which way is which!).

I am sure yours will be an English thread, but if they're treating you like an idiot, it might be worth throwing that in the mix...

I'm off to bed now, 2.30 am in Singapore!

 

[Toby_2009]

thought you might ask that!

The bottom bracket fits into the frame, the bit it fits into is called the bottom bracket shell. It screws in, so the shell has a thread. With an Italian thread it screws in one way, with the English it screws in the other way (don't ask me which way is which!).

I am sure yours will be an English thread, but if they're treating you like an idiot, it might be worth throwing that in the mix...

I'm off to bed now, 2.30 am in Singapore!

thanks very much mate, im sure ull hear their jaws hitting the floor from singapore!

My dads just got home and reckons they the LBS I got it from might do it for free since its only 6 months old and has not done massive mileage - what do you lads think?

 

[HJ]

thanks very much mate, im sure ull hear their jaws hitting the floor from singapore!

My dads just got home and reckons they the LBS I got it from might do it for free since its only 6 months old and has not done massive mileage - what do you lads think?

I think it should be covered by the warranty if the bike is only 6 months old, the LBS should do it for free...

 

[Big John]

Sounds like you have an adjustable bottom bracket which, if you knew how, you can service and take any play out. To be honest you're better off getting a sealed one (cartridge) as they need no maintenance and are reliable. Your local bike shop will fit this in no time. It's a simple job for them as they have all the proper tools.

They should measure the width of the axle and fit one the same length. Not sure how much they charge as I do my own maintenance but around £20 should get you the part.