Gears

[ben_miotti123]

I have 21 speeds on my mountain Bike.
But on each speed (1,2,3) gear 2 and 3 make a rattling noise which makes me sound like I am riding a motorbike, and gear 4 slips into gear 5, but gear 5 slips into gear 6. Can anyone help me?

 

[Rickshaw Phil]

It sounds like the indexing of the gears needs adjusting. It's fairly easy to do and there are lots of Youtube videos that will show you how. This seems to be the one that is most frequently linked to:

View: http://www.youtube.com/watch?v=SkzvfCaIbyQ

 

[ben_miotti123]

Thanks for the help, just realised this isn't the problem, who ever tuned the gears on my bike didn't included gear 1.