MTB gear help, sorry guys!
Discussion
Hello all.
I usually lurk around and browse the car bits, surprisingly! I've started getting into cycling, and own a Giant XTC, it has recently had a sram bottom bracket fitted. Last night I was out cycling on it, a mix of roads and dirt tracks, pretty soft stuff. The left hand side crank arm and pedal have snapped off the crank.
I'm unsure if I only need a new crankset, or I can get away with replacing just I assume the crank its self?
Also whilst I'm at it, the gears are pretty worn and only a few are really working well, with the others slipping. I am currently on a 3x9 set up, and am considering a 2x8 set up, as I hear its a cheaper route than a 2x10. What am I going to need to switch over to a set up like this?
Thanks for reading this, sorry I'm not too clued up on terminology regrading bikes, I'm hoping to learn quickly with them.
Cheers!
I usually lurk around and browse the car bits, surprisingly! I've started getting into cycling, and own a Giant XTC, it has recently had a sram bottom bracket fitted. Last night I was out cycling on it, a mix of roads and dirt tracks, pretty soft stuff. The left hand side crank arm and pedal have snapped off the crank.
I'm unsure if I only need a new crankset, or I can get away with replacing just I assume the crank its self?
Also whilst I'm at it, the gears are pretty worn and only a few are really working well, with the others slipping. I am currently on a 3x9 set up, and am considering a 2x8 set up, as I hear its a cheaper route than a 2x10. What am I going to need to switch over to a set up like this?
Thanks for reading this, sorry I'm not too clued up on terminology regrading bikes, I'm hoping to learn quickly with them.
Cheers!
Jesus!
Have you had the crank off at all recently? Looks like the threads have been pulled clean out, which on any other part of the bike i'd say would be down to over-tightening, but those crank bolts are pretty damn tough and you'd need to be swinging on it like a monkey to have that effect...
Either which way, you'll need a new bottom bracket. The crank arm itself may be salvageable, but depends if you have done any damage to the locator splines - the bolt (still in the middle of it) looks a bit skewiff, so the crank arm itself could be bent too.
Do you mind me asking what you were doing when it went? And are you "powerfully built" in the PH director sense?
Have you had the crank off at all recently? Looks like the threads have been pulled clean out, which on any other part of the bike i'd say would be down to over-tightening, but those crank bolts are pretty damn tough and you'd need to be swinging on it like a monkey to have that effect...
Either which way, you'll need a new bottom bracket. The crank arm itself may be salvageable, but depends if you have done any damage to the locator splines - the bolt (still in the middle of it) looks a bit skewiff, so the crank arm itself could be bent too.
Do you mind me asking what you were doing when it went? And are you "powerfully built" in the PH director sense?
I can't remember if the bit you've snapped is part of the BB or part of the crank on those... I fear it's the crank.
Anyway, if you need a new one, get a Shimano one, the new Deore ones are £50-£60 quid in all sorts of different permutations and come with rings and a BB so might be better value than fecking about messing out with your existing one.
SLX is a bit nicer and start about £85.
Anyway, if you need a new one, get a Shimano one, the new Deore ones are £50-£60 quid in all sorts of different permutations and come with rings and a BB so might be better value than fecking about messing out with your existing one.
SLX is a bit nicer and start about £85.
And just to address your other question:
At the rear, and to address the gear-slipping, it sounds like it is time to replace your chain and sprockets. Make sure you do these together, as you'll still get slipping afterwards if you only do one or the other. Going forward, you can keep tabs on these by checking the wear of the chain, and replacing the chain before it gets too bad - that way you can eek more life out of your sprockets too.
As for changing the gearing at the rear, I'd leave this well alone unless you really wanted to get your credit card out - depending on which way you're going (more or less gears), you'll be needing new shifters, rear mech, sprockets, hub/wheel (as the dishing is different), etc. Bucks basically. If I were you, I'd be replacing this stuff like-for-like.
RenaultK4J said:
Also whilst I'm at it, the gears are pretty worn and only a few are really working well, with the others slipping. I am currently on a 3x9 set up, and am considering a 2x8 set up, as I hear its a cheaper route than a 2x10. What am I going to need to switch over to a set up like this?
I would leave the chainset as-is - even if you need a new left crank arm, you can normally get these separately rather than having to buy both sides new. Unless you were desperate for a 2-chainring setup at the front end that is - if you were, then you should be able to use the existing shifter and front mech, just winding in the limit screws as appropriate on the mech when setting up. At the rear, and to address the gear-slipping, it sounds like it is time to replace your chain and sprockets. Make sure you do these together, as you'll still get slipping afterwards if you only do one or the other. Going forward, you can keep tabs on these by checking the wear of the chain, and replacing the chain before it gets too bad - that way you can eek more life out of your sprockets too.
As for changing the gearing at the rear, I'd leave this well alone unless you really wanted to get your credit card out - depending on which way you're going (more or less gears), you'll be needing new shifters, rear mech, sprockets, hub/wheel (as the dishing is different), etc. Bucks basically. If I were you, I'd be replacing this stuff like-for-like.
Thanks for the replies!
I'm not a slim lad, at around 16st! The thing that's pretty gutting is I wasn't even giving it any stick, I had done around 3.5 miles from my house, along road and one dirt track, it felt like there was play in the bottom bracket, as it had when I bought it around 2 weeks ago, its recently had an SRAM one fitted. I thought it might have been a pedal loose or something, but knew it didn't feel good, the plan was to limp it home. Next thing it just snapped clean off. My fault for continuing, but I guess the damage was already done!
This sucks, as I just want to get out riding the thing! Thanks again chaps.
I'm not a slim lad, at around 16st! The thing that's pretty gutting is I wasn't even giving it any stick, I had done around 3.5 miles from my house, along road and one dirt track, it felt like there was play in the bottom bracket, as it had when I bought it around 2 weeks ago, its recently had an SRAM one fitted. I thought it might have been a pedal loose or something, but knew it didn't feel good, the plan was to limp it home. Next thing it just snapped clean off. My fault for continuing, but I guess the damage was already done!
This sucks, as I just want to get out riding the thing! Thanks again chaps.
Given the first picture where the casing is distorted, its happened on a downstroke and I'd guess its a combination of over tightning the bolt and bad luck. Looks like the crank itself as taken a fair few big hits in that last picture too which might be a factor?
As for 2x8, it sounds a bit odd especially as you would be using 9 speed gearing? A 2x10 XT (drivetrain) groupset is £300 from bike discount and solves all your problems, new chainset, cassette, mechs and shifters. To bodge 2x8 form your current set up would leave you with a very low or high gearing at the front depenedent upon which chainring you removed from the front and you would essentially be using the 9 speed cassette so you might as well go 2x9 for more range but again, are you dropping the inner or outer ring?.
As for 2x8, it sounds a bit odd especially as you would be using 9 speed gearing? A 2x10 XT (drivetrain) groupset is £300 from bike discount and solves all your problems, new chainset, cassette, mechs and shifters. To bodge 2x8 form your current set up would leave you with a very low or high gearing at the front depenedent upon which chainring you removed from the front and you would essentially be using the 9 speed cassette so you might as well go 2x9 for more range but again, are you dropping the inner or outer ring?.
Hi Pablo.
I would drop the inner ring, as in the low geared front cog? My apologies if I've got the wrong, also yeah it went on a down stroke, I think this bikes had a real hard life before I bought it, I got it used. I might have bought a 'pup'
I think I'll follow from what CCR says and go for a new chain and sprockets.
I would drop the inner ring, as in the low geared front cog? My apologies if I've got the wrong, also yeah it went on a down stroke, I think this bikes had a real hard life before I bought it, I got it used. I might have bought a 'pup'
I think I'll follow from what CCR says and go for a new chain and sprockets.
I'd get a new chainset because you dont know what stress that axle had on it before the crank went and its been "matched " with that crank for a few years so will have worn together. sticking a brand new crank on the chainset will not last long as I bet there will be play, albeit only very minor, between the axle and the new crank.
I wouldn't mess around trying to fix it, just get a complete new crankset, as above £50-£60 will get you everything.
eg
http://www.chainreactioncycles.com/shimano-deore-m...
eg
http://www.chainreactioncycles.com/shimano-deore-m...
megaphone said:
I wouldn't mess around trying to fix it, just get a complete new crankset, as above £50-£60 will get you everything.
eg
http://www.chainreactioncycles.com/shimano-deore-m...
What he says ^^^^. To be honest I get through bottom brackets every 3000kms (or even less) and I've learnt over the years just to change the BB and crank at the same time. eg
http://www.chainreactioncycles.com/shimano-deore-m...
It's an easy DIY job if you have the Shimano BB socket (looks like a Shimano from the picture) It's worth investing in one TBH; they're not that expensive.
ETA, just seen you have a SRAM BB. Well if you change to Shimano get the Shimano BB socket for the future!
Edited by caiss4 on Friday 28th February 15:03
Okay, I think I'll go for the one in the link, just one more thing (Columbo voice) what length and teeth should I be looking at going for?
I'm useless with bikes at the moment, and appreciate the help and advice, I am happy to work on the bike myself, and have worked on my cars at home
no problems getting oily hands.
I'm useless with bikes at the moment, and appreciate the help and advice, I am happy to work on the bike myself, and have worked on my cars at home
no problems getting oily hands. caiss4 said:
What he says ^^^^. To be honest I get through bottom brackets every 3000kms (or even less) and I've learnt over the years just to change the BB and crank at the same time.
It's an easy DIY job if you have the Shimano BB socket (looks like a Shimano from the picture) It's worth investing in one TBH; they're not that expensive.
Wow - I have swapped though several BBs and NEVER needed to change the cranks!It's an easy DIY job if you have the Shimano BB socket (looks like a Shimano from the picture) It's worth investing in one TBH; they're not that expensive.
Given BBs are £10-20 - yours is an expensive method!!
If there was play in the OP's setup I strongly suspect it would be the crank arm working its way OFF not overtightening.
Overtightening is a problem with square taper BBs not the Truativ one I think he has in the pics.
It looks like he has taken the end off the spline which would happen if that is the only bit taking all the pressure each pedal-stroke.
Definitely just replace the chain and cassette (sprockets at the back) rather than the whole chainset - if you are only just getting into it I can't imagine you really know whether you want 2 or 3 cogs up front.
pablo said:
its the same tool, its why my bikes are Sram or Shimano as I only need one set of tools and the components are interchangeable unlike the Romanian groupsets 
Wasn't sure but thought they might be. My original BB was SRAM and I replaced it with Shimano. Seem to recall removing the old BB using a Stilson wrench 
(bought the BB socket before fitting the new BB however!)
walm said:
caiss4 said:
What he says ^^^^. To be honest I get through bottom brackets every 3000kms (or even less) and I've learnt over the years just to change the BB and crank at the same time.
It's an easy DIY job if you have the Shimano BB socket (looks like a Shimano from the picture) It's worth investing in one TBH; they're not that expensive.
Wow - I have swapped though several BBs and NEVER needed to change the cranks!It's an easy DIY job if you have the Shimano BB socket (looks like a Shimano from the picture) It's worth investing in one TBH; they're not that expensive.
Given BBs are £10-20 - yours is an expensive method!!
If there was play in the OP's setup I strongly suspect it would be the crank arm working its way OFF not overtightening.
Overtightening is a problem with square taper BBs not the Truativ one I think he has in the pics.
It looks like he has taken the end off the spline which would happen if that is the only bit taking all the pressure each pedal-stroke.
Definitely just replace the chain and cassette (sprockets at the back) rather than the whole chainset - if you are only just getting into it I can't imagine you really know whether you want 2 or 3 cogs up front.
The last time I replaced the BB I was having a number of problems with the drivetrain so ended up replacing the cassette, chain and for good measure did the cranks as well. Perhaps next time I might just get away with a new BB and chain as I think the problem before was caused by a rather too well-worn chain.
Is it just me, or are these external BBs a load of rubbish? My 20 year old MTB is on the original square taper BB, my old cyclocross bike had had the same square taper BB for years, my winter bike has had the same square taper BB for years as well. My modern MTB has been through two Shimano BBs in 18 months, my eldest's CX bike FSA BB eats bearings on a regular basis, and my CX bike has done 12 races on it's BB and feels awful.
Don't set me off on cartridge 'sealed for life' headset bearings either, they are sealed for life, which is about 12 months.
Don't set me off on cartridge 'sealed for life' headset bearings either, they are sealed for life, which is about 12 months.
Hi guys, me again.
I just wanted to thank everyone for the great advice in this thread! I'm just about to purchase the crankset that was linked in here! Also looking at getting a new rear cassette and chain, just to be on the safe side with it!
ETA just had the old dear check my bike, as I'm not at home. It appears I have a 3x8 set up on the bike!
Cheers
I just wanted to thank everyone for the great advice in this thread! I'm just about to purchase the crankset that was linked in here! Also looking at getting a new rear cassette and chain, just to be on the safe side with it!
ETA just had the old dear check my bike, as I'm not at home. It appears I have a 3x8 set up on the bike!
Cheers
Edited by RenaultK4J on Saturday 1st March 19:21
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