Sith Happens Posted April 24, 2017 Share Posted April 24, 2017 A couple of years ago my wife and I bought new Mountain Bikes, not expensive ones, think they were like £125 each or something from Halfords. We only 'tootle' along, and have used them probably 7 or 8 times in the 2 years. Yesterday mine started feeling like it had a vibration, and then started when freewheeling the chain coming slack. I could see the gear unit was moving backwards and forwards as it did. As soon as i started peddling again all was ok. Any ideas what might be causing it? Link to comment Share on other sites More sharing options...
Gaspode Posted April 24, 2017 Share Posted April 24, 2017 The rear derailleur (the gear unit with the two little pulley cogs in it) is designed to keep tension in the chain via a spring - sounds as if either the unit has got gunged up so that the little cogs aren't spinning properly, or the spring is being restricted in some way (unlikely if you've only ridden it a few times - unless you've been riding through a lot of mud or you've got something stuck in it). Compare it with the unit on your wife's bike to see if there are any obvious differences... If it's not that, it;s most likely that either the bolt that fastens the derailleur to the frame has come lose or else you've knocked the unit on something and it's out of alignment with the frame (though you'd likely notice that as it would cause problems when you tried to change gear). Try oiling it in the first instance (lift the rear of the bike and dribble some oil on the chain while turning the pedals and oil the centre of the 2 little cogs to make sure they run free). It's generally considered a bad idea to use WD40 as it can cause increased chain wear, but that's an option if you don't have any oil handy - may at least get things running again.... There are numerous youtube videos that will show you how a derailleur works. Whatever you do, don't touch the little screws (it's really tempting to start fiddling), but adjusting those will potentially mess up your gear changing - and then you're off to the bike shop to have it reset. Link to comment Share on other sites More sharing options...
Sith Happens Posted April 24, 2017 Share Posted April 24, 2017 1 hour ago, Gaspode said: The rear derailleur (the gear unit with the two little pulley cogs in it) is designed to keep tension in the chain via a spring - sounds as if either the unit has got gunged up so that the little cogs aren't spinning properly, or the spring is being restricted in some way (unlikely if you've only ridden it a few times - unless you've been riding through a lot of mud or you've got something stuck in it). Compare it with the unit on your wife's bike to see if there are any obvious differences... If it's not that, it;s most likely that either the bolt that fastens the derailleur to the frame has come lose or else you've knocked the unit on something and it's out of alignment with the frame (though you'd likely notice that as it would cause problems when you tried to change gear). Try oiling it in the first instance (lift the rear of the bike and dribble some oil on the chain while turning the pedals and oil the centre of the 2 little cogs to make sure they run free). It's generally considered a bad idea to use WD40 as it can cause increased chain wear, but that's an option if you don't have any oil handy - may at least get things running again.... There are numerous youtube videos that will show you how a derailleur works. Whatever you do, don't touch the little screws (it's really tempting to start fiddling), but adjusting those will potentially mess up your gear changing - and then you're off to the bike shop to have it reset. Ok thanks. I will give it a try, ordered some proper bike oil so will try when comes, not sure if worth it or not, used to just put engine oil on when was a kid Link to comment Share on other sites More sharing options...
MuespachRam Posted April 24, 2017 Share Posted April 24, 2017 1 hour ago, Paul71 said: Ok thanks. I will give it a try, ordered some proper bike oil so will try when comes, not sure if worth it or not, used to just put engine oil on when was a kid On a 125 pound bike you will be fine with engine oil. Back ip for the previous poster, it is more than likely gunked up, when you out oil on it get an old toothbrush (or the one you are using at the moment if you really want!) and give the whole gear system a scrub to remove any debris. If the bike sits a decent amount of time between rides it is a good idea to do this after a ride so the grit and mud don't get lodged in there too. And definitely don't touch any of r screws down there....you will never get it to change gear properly again.! Good luck. Link to comment Share on other sites More sharing options...
Sith Happens Posted April 24, 2017 Share Posted April 24, 2017 Just now, MuespachRam said: On a 125 pound bike you will be fine with engine oil. Back ip for the previous poster, it is more than likely gunked up, when you out oil on it get an old toothbrush (or the one you are using at the moment if you really want!) and give the whole gear system a scrub to remove any debris. If the bike sits a decent amount of time between rides it is a good idea to do this after a ride so the grit and mud don't get lodged in there too. And definitely don't touch any of r screws down there....you will never get it to change gear properly again.! Good luck. Thanks.Wonder if my wife will notice if i use hers Link to comment Share on other sites More sharing options...
McRamFan Posted April 24, 2017 Share Posted April 24, 2017 WD40, fixes everything. Link to comment Share on other sites More sharing options...
MuespachRam Posted April 24, 2017 Share Posted April 24, 2017 11 hours ago, McRamFan said: WD40, fixes everything. Except chains...which it screws up Link to comment Share on other sites More sharing options...
Gypsy Ram Posted April 25, 2017 Share Posted April 25, 2017 12 hours ago, McRamFan said: WD40, fixes everything. on a 125 quid bike for sure. Link to comment Share on other sites More sharing options...
mozza Posted April 25, 2017 Share Posted April 25, 2017 you can get WD with PTFE in it which acts as a lubricant. Anyway, a small paint brush dipped in petrol will disperse any dirt around the cogs, clean the cogs and chain well, then use 3in1oil all over, that should cure the blighter. Failing that, catch the bus!! Link to comment Share on other sites More sharing options...
McRamFan Posted April 25, 2017 Share Posted April 25, 2017 7 hours ago, MuespachRam said: Except chains...which it screws up Never had an issue. Link to comment Share on other sites More sharing options...
Sith Happens Posted April 25, 2017 Share Posted April 25, 2017 1 hour ago, mozza said: you can get WD with PTFE in it which acts as a lubricant. Anyway, a small paint brush dipped in petrol will disperse any dirt around the cogs, clean the cogs and chain well, then use 3in1oil all over, that should cure the blighter. Failing that, catch the bus!! Yeah, sadly those pesky buses do get in the way down the nutbrook trail Link to comment Share on other sites More sharing options...
Coneheadjohn Posted April 25, 2017 Share Posted April 25, 2017 On 24/04/2017 at 07:07, Paul71 said: A couple of years ago my wife and I bought new Mountain Bikes, not expensive ones, think they were like £125 each or something from Halfords. We only 'tootle' along, and have used them probably 7 or 8 times in the 2 years. Yesterday mine started feeling like it had a vibration, and then started when freewheeling the chain coming slack. I could see the gear unit was moving backwards and forwards as it did. As soon as i started peddling again all was ok. Any ideas what might be causing it? My bike has a vibration caused by having to carry me around. Either that or its crying in pain. Link to comment Share on other sites More sharing options...
mozza Posted April 25, 2017 Share Posted April 25, 2017 I was thinkin you could trade em both in for a tandem Link to comment Share on other sites More sharing options...
Sith Happens Posted April 25, 2017 Share Posted April 25, 2017 12 minutes ago, mozza said: I was thinkin you could trade em both in for a tandem true i think a tandem would be a very good idea. Link to comment Share on other sites More sharing options...
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