How do you add/remove gears on a mountain bike?

You should be able to reach 22-25 mph depending on how fast you pedal. It is hard to maintain that speed on a mountain bike.

By 'bad', what do you mean? The lowest gears are not low enough? Or the highest gears are too high?

Certainly you have a range of gear ratios and most of them are fine for most of what you do.

It is possible to get the chain-rings replaced with a smaller or larger set.

Go to a good shop and ask about that, if that's the problem.

you could desire to alter the swing of the front mech (or derailleur). this is carried out by utilising turning screws on the derailleur unit to aline the unit so as that the chain ameliorations gears easily. you do no longer say how previous the bike is, yet whilst its long previous that far i could think of its getting on a for some years, so which you need to to get a sparkling mech, or possibly even something so trouble-free as a sparkling cable, which if full of gunk merely won't flow interior its casing, and could desire to be the reason the gears are caught. a save might actually assist you with this (yet please do no longer bypass to Halfords - down with grasping firms). As for the fork, the main adjuster you're probable to have (on the precise of one or the two legs) is a preload adjuster. This adjusts the sag (the quantity the fork drops once you take a seat on the bike) and could be set to around 20% or so of the great shuttle. As for the bouncing around - this is a damping venture, and additionally you're able to do nicely to get the fork serviced if its a great one, or replaced with a sparkling one if its no longer rather easily worth the fee.

You will have either a freewheel, which is a cluster or set of sprockets riveted together and screwed onto the rear hub, or you will have a cassette which consists of a set of individual sprockets and spacers mounted on the hub. You can change the individual sprockets of the cassette or the whole freewheel cluster as a unit. Both take a special removal tool. You can find videos on Youtube which explain how to do the work or you can take it to a bike shop and have it done.