Cycling UK Forum

I have a 1996 Trek 970 Singletrack mountain bike, which has 21 speed & I 'd like to keep this bike for another few years. Would it be possible to add more gears up to 27?

I assume that you have a 3x7 setup and you want to go 3x9.
First drawback is that 9 sprockets won't fit in place of the 7. The freehub isn't wide enough. So that will mean a new freehub or complete hub fitted to your existing wheel (or a complete new wheel).
Next, of course, is a new 9 speed cassette and chain.
Then you would need to replace the 7 speed shifter with a 9 speed of course.
You may be able to retain the rear derailleur but I would budget for a new one.

It is doable, just need the cash.

As cycleruk says, yes it is. But my question is: why would you want to? You might be better off just customising the ratios that you already have such that they suit you better - it'd be cheaper than adding a further six arbitrary ratios.

Si's point is a very good one. Even after putting on a 9 speed cassette, you're probably not going to wind up with gears that are mch different to what you now have - they will just be stacked closer together. Do you want a lower/higher bottom gear, or a lower/higher top gear? When you decide what you want, you can source a different 7 speed cassette and spend a lot less money with a near identical result.

Si wrote:As cycleruk says, yes it is. But my question is: why would you want to? You might be better off just customising the ratios that you already have such that they suit you better - it'd be cheaper than adding a further six arbitrary ratios.

+1
The main question you've got to ask yourself is why do I want more gears and what advantage does it give me.
Try to forget that seven is old, nine is cool.Its got to be what works best for me.

Many thanks for your advice.

I currently have grip shift gears that is becoming quite stiff on the right that the rubber part has worn out in ribbons hence the reason of looking at improving gears on the bike.

I don't think they make grip shift gears anymore do they?

Gizmo wrote:Many thanks for your advice.

I currently have grip shift gears that is becoming quite stiff on the right that the rubber part has worn out in ribbons hence the reason of looking at improving gears on the bike.

I don't think they make grip shift gears anymore do they?

Yes they do!

http://www.sjscycles.co.uk/7-speed-shim ... prod18901/

or changing to trigger shift isn't too bad either

http://www.sjscycles.co.uk/shimano-altu ... prod24216/

I got a set that someone else was chucking out as the rubbers on the grip-shifter had gone sticky. Going from 7 to 8 or 9 is going to be expensive IMHO!

Is your rear wheel a freewheel or a freehub? If it's a freehub it is possible (I beleive but haven't tried it) to change the freehub body for an 8/9 speed one and re-dish the wheel. Once you've done this you can fit either 8 or 9 speed cassettes. If the size of your largest rear sprocket remained the same with 8 you could keep the same chain but for 9 you'd need a new chain.

If you have a freewheel any increase in the number of gears means a new rear hub.

Personally I'd keep it running at 7 speeds. I have a 7 speed and an 8 speed bike and the 7 speed is much less fiddly and finaky than the 7 speed which seems bomb proof by comparison.