Rear gears banging and pedals groaning

[rh100]

Hi

I have a problem with my MTB. The bike has only a few hundred miles so far, BUT is now over six years old and was sat not doing anything all that time.

Now it's getting some use it seems to be showing a few problems.

Firstly, I have adjusted the high and low stops on the rear derailer and adjusted the tension, so when it is on a stand with the pedals spinning, pulling the gear cable or turning the gripshift the chain moves nicely up and down the gears, doesn't seem to hesitate.

However, when riding the bike uphill, and changing down gear at low speed say from 3 to 2, the pedals seem to start to spin too easy, even loose, before it bites and clunks in to gear and allows me to continue pedaling. This obviously causes a major slowdown in momentum.

I have this problem with two MTB's actually, both same age and both with Shimano SIS derailers.

Might be worth pointing out that I also had the chain derail from the front cogs, when changing down from middle to left, it came clean off, it might have been down to a bad gear change though as I've not had it happen before or since, and to be fair I havn't checked the H and L stops on the front yet, just the back one.

I'm not sure if it's a problems with the derailers or the chain - or is it likely the cable itself becoming a bit stiff? If so, do you have to buy a cable specific to the bike or just buy a length of cable, length of cable sheath and cut to measure? (any idea of cost?)

The second problem is that on one of the bikes, the pedals seem to groan when riding along, I'm 'fairly' certain it's the pedals because of the timing of it, seems to be worse on the left side going down rather than the right though. Also the pedals and crankarm (is that right? the pedal arms?) can be waggled back and forth slightly - it's as if the arm is loose within the frame, not by much but noticeable, and I'm concerned it could let me down far from home - any suggestions.

Whilst I'm fairly new to bikes, I'm not completely useless with a spanner and could do without the cost of a visit to the LBS unless for necessary parts.

TIA

Rich

 

[Twenty Inch]

Did you lube the gear cable when you did all the fettling?

Get the cranks tightened - your lbs will sell you a special crank removal tool which will do it, and that'll be the start of your toolset.

 

[rh100]

Did you lube the gear cable when you did all the fettling?

Get the cranks tightened - your lbs will sell you a special crank removal tool which will do it, and that'll be the start of your toolset.

Thanks TI - I'll get some lube and try that before doing anything more drastic. I'll have a look at one of those tools aswell, should be worth the investment I guess.

 

[Chuffy]

Probably stating the obvious but...

Don't ride the bike while you ponder fixing it! If you ride it with a loose crank then you'll very likely damage the hole where the bottom bracket axle enters the crank. Cranks are usually aluminium and the bottom bracket will most like likely be steel. Steel is harder than ali and if it's wobbling, the axle will 'round out' the hole and you'll never get the crank on tight again. You should be able to tighten up the crank yourself with an 8mm allen key (I think it's 8mm) and a length of piping slipped over for added leverage.


* - all of this assumes that you have an old fashioned square taper bottom bracket and also assumes that the problem isn't with the bottom bracket working loose in the frame. If that is the case then you'll have to remove the crank and invest in a bottom bracket tool (check for compatibility with your BB) which will cost about £5-£10. You can't have too many tools and the ones mentioned so far are very handy to have around even if you don't need them right now.

 

[rh100]

Thanks for the advice Chuffy, I didn't think about causing more damage. However, I popped into Halfords on the way home and made enquiries about tools (my lbs is a bit far away to get there after work), the chap on the bike counter was actually very helpful, I wheeled the bike in and tried to find the right tool, but they didn't have the right one in stock, so he just did it for me with his own tools - no charge! Took it for a spin round the block and seems a lot better so quite pleased.