Seven to eight speed conversion

[Mr Pig]

Hello :0)

One of the guys at work has a 21-speed Garry Fisher MTB which he'll like to add more gears to. What would be involved? From what I can see he'll need:

8 or 9 speed cassette
shifter
derailleur
chain
chainrings
free hub

Will the spindle be too short? Will the geometry of the rear dropouts be ok? I assume you'd need to open them up a little, it's a steel bike.

Cheers dudes and dudets.

 

[fossyant]

Hubs need to be 135mm - he should be OK as my early 90's MTB is 135mm.

For an 8 speed, he won't need new chain rings or mechs - just hub/wheel, cassette (or 3mm spacers) and shifters.

For 9, as the chain is narrower, he may need new chain rings !

 

[02GF74]

and more powerful brakes as the extra gears wil mean he will go much faster.

 

[robbarker]

I'd tell him not to worry about 8 speed and just replace the 7 speed components as they wear out. IME changing numbers of gears on older bikes is fraught with gotchas. Unless he knoews exactly what he's doing it will not be worth the tiny benefit derived.

 

[Mr Pig]

what he's doing it will not be worth the tiny benefit derived.

I kinda said that to him. I told him to count the teeth on the smallest gear on the cassette and buy a smaller cassette if it was less than eleven, and buy a bigger chain ring for the front. He's pretty tight, he'll probably do nothing! ;0)