matt.price Posted January 11, 2010 Report Share Posted January 11, 2010 my left crank arm is wobbling! As in every time a turn a full crank turn it changes position! I've tried tightening the crank bolt up! Help needed please! The bottom bracket is a square taper and the crank arm i purchased a month or two ago! will it get better in time. thanks Quote Link to comment Share on other sites More sharing options...
Nick Melson Posted January 11, 2010 Report Share Posted January 11, 2010 Crank will most probs be rounded or the taper on the bb is rounded but as its a square taperd bb use the coke can trick Quote Link to comment Share on other sites More sharing options...
aener Posted January 11, 2010 Report Share Posted January 11, 2010 How does it change position? Like - does it rotate around the bottom bracket, or does it flap in and out a bit? If it's rotating, either the crank, or the BB are royally mashed. If it's flapping in and out, it could be that you just need to tighten the bolt some more (don't be afraid to give it some welly) - it it could also be that the cranks tapers are dead, or the BB's rounding off. If the crank arm was new, I'd say it was the bottom bracket - but a lot of people will sell duff cranks 'cause they're bastards. Quote Link to comment Share on other sites More sharing options...
matt.price Posted January 11, 2010 Author Report Share Posted January 11, 2010 How does it change position? Like - does it rotate around the bottom bracket, or does it flap in and out a bit? If it's rotating, either the crank, or the BB are royally mashed. If it's flapping in and out, it could be that you just need to tighten the bolt some more (don't be afraid to give it some welly) - it it could also be that the cranks tapers are dead, or the BB's rounding off. If the crank arm was new, I'd say it was the bottom bracket - but a lot of people will sell duff cranks 'cause they're bastards. ok mate , ill give the crank bolt some welly its like flapping in and out sooo ok thanks Quote Link to comment Share on other sites More sharing options...
Ben John-Hynes Posted January 11, 2010 Report Share Posted January 11, 2010 Before you tighten it up, take the crank off and have a good look at the tapers and the BB. If they're completely f**ked then there's no point in putting it back on. Quote Link to comment Share on other sites More sharing options...
Scooter916 Posted January 11, 2010 Report Share Posted January 11, 2010 the BB is hardened cro-moly and the cranks is aluminum so the crank will die before the BB, if you ride especially trials with a loose crank bolt it allows the crank to loosen and causing the taper to round out. Now is the perfect opportunity to upgrade to an ISIS system Quote Link to comment Share on other sites More sharing options...
I am ze best Posted January 11, 2010 Report Share Posted January 11, 2010 This happened to me and I tred lok tite on it and it dont work. Strangly its never the drive side? If it were me I would just buy a new crank. Mine lasted for like 3/4 months and seemed to get worse as time went on. Quote Link to comment Share on other sites More sharing options...
TTidders Posted January 11, 2010 Report Share Posted January 11, 2010 Try checking the bb the bearing might have gone. depending on what type of bb you have got. Quote Link to comment Share on other sites More sharing options...
Rhys Jones tonna trials Posted January 11, 2010 Report Share Posted January 11, 2010 As a bike machanic my self that crank is more than lightly rounded this has happend by riding the bike whilst the crank was looose this will need replacing. check your crank bolts before replacing it but its not likly to be anything else Quote Link to comment Share on other sites More sharing options...
matt.price Posted January 11, 2010 Author Report Share Posted January 11, 2010 the BB is hardened cro-moly and the cranks is aluminum so the crank will die before the BB, if you ride especially trials with a loose crank bolt it allows the crank to loosen and causing the taper to round out. Now is the perfect opportunity to upgrade to an ISIS system Hi mate . I've be looking at the Isis bb and cranks but it's very exspensive. So I need some very good reason to upgrade to Isis , as in performance and strengh wise Thanks Quote Link to comment Share on other sites More sharing options...
max-t Posted January 11, 2010 Report Share Posted January 11, 2010 Hi mate . I've be looking at the Isis bb and cranks but it's very exspensive. So I need some very good reason to upgrade to Isis , as in performance and strengh wise Thanks There you go, you've just said it. ISIS is stronger and performs better. you can get a good set up for under £80. Quote Link to comment Share on other sites More sharing options...
matt.price Posted January 11, 2010 Author Report Share Posted January 11, 2010 There you go, you've just said it. ISIS is stronger and performs better. you can get a good set up for under £80. the main thing iam worried about , is are bottom brackets hard to repace :@ thanks Quote Link to comment Share on other sites More sharing options...
Ben John-Hynes Posted January 11, 2010 Report Share Posted January 11, 2010 the BB is hardened cro-moly and the cranks is aluminum so the crank will die before the BB How do you know he bought them at the same time? Quote Link to comment Share on other sites More sharing options...
max-t Posted January 11, 2010 Report Share Posted January 11, 2010 (edited) the main thing iam worried about , is are bottom brackets hard to repace :@ thanks No, not at all. EDIT: LEEROY!!!! Edited January 11, 2010 by max-t Quote Link to comment Share on other sites More sharing options...
davey1991 Posted January 12, 2010 Report Share Posted January 12, 2010 As a bike machanic my self that crank is more than lightly rounded this has happend by riding the bike whilst the crank was looose this will need replacing. check your crank bolts before replacing it but its not likly to be anything else Means little or nothing on this forum i'm affraid as most people will. A. Ignore you or will. B. know as much as you do anyway. You may just have to give the bolt some more torque. I had this problem i took my crank arm off cleaned the tapers thoroughly and greased them again, tightened them back on and voila solved. Dirt may be preventing your crank arm from moving up the taper as far as it needs to. If worst comes to worst you may need to replace the crank arm or BB. Quote Link to comment Share on other sites More sharing options...
Ash-Kennard Posted January 12, 2010 Report Share Posted January 12, 2010 Means little or nothing on this forum i'm affraid as most people will. A. Ignore you or will. B. know as much as you do anyway. You may just have to give the bolt some more torque. I had this problem i took my crank arm off cleaned the tapers thoroughly and greased them again, tightened them back on and voila solved. Dirt may be preventing your crank arm from moving up the taper as far as it needs to. If worst comes to worst you may need to replace the crank arm or BB. i know more than all of you put together muwahaha Quote Link to comment Share on other sites More sharing options...
matt.price Posted January 14, 2010 Author Report Share Posted January 14, 2010 Hi guys Just a quick update ..... I've tightened up the crank bolt as much as possible..... I think it starts alright then gets worse..... I think it works it way lose ...... Help! Quote Link to comment Share on other sites More sharing options...
Ben John-Hynes Posted January 14, 2010 Report Share Posted January 14, 2010 The splines/tapers on your crank are work then. You'll need new cranks to sort it properly. Quote Link to comment Share on other sites More sharing options...
multi tasking male Posted January 14, 2010 Report Share Posted January 14, 2010 i had this problem with the cranks on my bmx and i replaced the bearings which helped a bit and i just put some lock tite on the bolts before i put them in and its fine now, worked a treat. Quote Link to comment Share on other sites More sharing options...
Jordy P Posted January 14, 2010 Report Share Posted January 14, 2010 Hi guys Just a quick update ..... I've tightened up the crank bolt as much as possible..... I think it starts alright then gets worse..... I think it works it way lose ...... Help! Could you take a picture of the crank on/off next to the bb for people to see? Because if it is the crank arm that has rounded, someone will be able to diagnose it from a pic! Quote Link to comment Share on other sites More sharing options...
matt.price Posted January 14, 2010 Author Report Share Posted January 14, 2010 ok mate ill take the crank arm off and take a picture of the arm and the bb. Pictures tomorow ... Quote Link to comment Share on other sites More sharing options...
Twitch-119 Posted January 15, 2010 Report Share Posted January 15, 2010 (edited) Hi, just reading through, and i, like everyone else had the same problem, but, if you have the cranks i had, then this should help |-----|-------- <-- bolt end of crank, if you can imagine the square taper being perpindicular to the shaft of the crank (Taper is the wierd square | [-] | -------- <-- thing, middle left, incase you can't understand the diagram) this type, in my experience, is about as useful as a peado |-----|-------- <-- trying to thread a needle in a nursery, right now if you can imagine it being 25 degrees turned like this ````````/ ``````` / `````` / ``````/``<-- I know not exactly 25 degrees but it gives you an idea, as oppossed to the above it is not perpindicular and i find this works alot ````` / ``````/ ``<-- better, i have been riding this design for the best part of 7 months and it has not failed me yet, i havent ugraded because mainly `````/ ` [-]``/``` <-- i cant save up for love nor money, ha ironic, sorry, anyway this works well. sorry for the random commers it wouldn't fit properly ```````````/`````<-- on the page and would not look like anything i wanted it to ``````````/ And i really hope this works well for you guys cus' if you cant understand it then its been a massive waste of my time, bout 3 hours, and i accidentally deleted the first one i did, very annoying, so if it helps, much appriciated, again very very very apolagetic of the diagram i just hope it can make as much sense to you as it does me? and the bloke who said give it welly, THAT IS VERY GOOD, i got a mate to hold my bike, and got a 4 metre'ish scafolding pole, attatched it to the allen key on he end of the bolt and had some fun hanging off it, was PRO! Twitch EDIT: the first one is crap, the second works! Edited January 15, 2010 by T-Proboy13 Quote Link to comment Share on other sites More sharing options...
multi tasking male Posted January 15, 2010 Report Share Posted January 15, 2010 that was a well good reply mate, thumbs up to you , great diagrams. Quote Link to comment Share on other sites More sharing options...
scotty007 Posted January 15, 2010 Report Share Posted January 15, 2010 Hi, just reading through, and i, like everyone else had the same problem, but, if you have the cranks i had, then this should help |-----|-------- <-- bolt end of crank, if you can imagine the square taper being perpindicular to the shaft of the crank (Taper is the wierd square | [-] | -------- <-- thing, middle left, incase you can't understand the diagram) this type, in my experience, is about as useful as a peado |-----|-------- <-- trying to thread a needle in a nursery, right now if you can imagine it being 25 degrees turned like this ````````/ ``````` / `````` / ``````/``<-- I know not exactly 25 degrees but it gives you an idea, as oppossed to the above it is not perpindicular and i find this works alot ````` / ``````/ ``<-- better, i have been riding this design for the best part of 7 months and it has not failed me yet, i havent ugraded because mainly `````/ ` [-]``/``` <-- i cant save up for love nor money, ha ironic, sorry, anyway this works well. sorry for the random commers it wouldn't fit properly ```````````/`````<-- on the page and would not look like anything i wanted it to ``````````/ And i really hope this works well for you guys cus' if you cant understand it then its been a massive waste of my time, bout 3 hours, and i accidentally deleted the first one i did, very annoying, so if it helps, much appriciated, again very very very apolagetic of the diagram i just hope it can make as much sense to you as it does me? and the bloke who said give it welly, THAT IS VERY GOOD, i got a mate to hold my bike, and got a 4 metre'ish scafolding pole, attatched it to the allen key on he end of the bolt and had some fun hanging off it, was PRO! Twitch EDIT: the first one is crap, the second works! Ahhhhhhh WTF Am i missing something here or is my laptop still in the stone ages and dosent work properley cause all i can see is a lot of sqigle and arrows so where do you get "Good Post " from im not sure. If i was you id listen to the advice given by the other members on page 1. +1 for effort on the post but just dont get it sorry mate . Quote Link to comment Share on other sites More sharing options...
Twitch-119 Posted January 15, 2010 Report Share Posted January 15, 2010 Ahhhhhhh WTF Am i missing something here or is my laptop still in the stone ages and dosent work properley cause all i can see is a lot of sqigle and arrows so where do you get "Good Post " from im not sure. If i was you id listen to the advice given by the other members on page 1. +1 for effort on the post but just dont get it sorry mate . I beleive your screen setting are making it come out as how you are seeing it you might have a smaller sceen res. set up so it comes out strange, like you said in above quote. I ask not for you to understand this but if 'matt.price' does, as he is the one i am trying to help, i dont mean to sound arrogant in what i have put down then, but i can t sem to put it any other way. Twitch Quote Link to comment Share on other sites More sharing options...
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