Gears.....

[leedsmick]

Can anyone explain something that i'm sure is obvious to most.

The spec on my mountain bike is 42/32/22T - 175mm-18"/20"/22" 170MM -14"/16"

I have 21 gears.

How do i know which ones cross over,

eg is being in 1st on the big ring and 6th on the small the same as being in 2nd on the big and 2nd on the small if that makes sense?

And is the 42 32 22 the number of teeth on each cog?

 

[Citius]

Without using a gear calculator, there is no easy way of telling, and it doesn't matter anyway. Just avoid running the chain at extreme crossover angles in whichever gear you are in. 42/32/etc represents the tooth count, as you suggest.

 

[sight-pin]

The spec on my mountain bike is 42/32/22T - 175mm-18"/20"/22" 170MM -14"/16"

42/32/22T = the amount of teeth.
175mm-18"/20"/22" = Is the length of your crank arms with a 18"/20"/22" size frame or 170MM -14"/16" with a 14"/16" frame.
The gears depend on your 7 speed cassette ratios.

 

[sidevalve]

As above just avoid biggest to smallest or smallest to biggest other than that it doesn't matter at all. I suspect you will spend most of your time on road in the top two front sprockets and maybe off road in the bottom two but it's no big deal

 

[Markymark]

No you need to avoid more than just biggest to smallest. Ftont ring smallest is for very steep climbs only. Middle and largest normally. I use largest and 4 to smallest on rear when flatish. Use middle and 2-6 on rear if hilly. Front ring change should not be iften. Shift up an diwn rear. Change front if hilliness changes only.

 

[gavintc]

Gears are not that complex. At the front you have chain rings and at the back a cassette of teeth. Imagine having a ring at the front with 48teeth and one at the back with 12 teeth. Every time you turn the pedal over, you move 48 teeth. This results in the back wheel going round 4 times (48 divide by 12). Now change to a 22 teeth ring at the front and 22 teeth at the back. Every turn of the pedal turns the back wheel once. You go less distance, but it is less effort. Simples.

 

[leedsmick]

Thanks everyone for your replies. I find that unless its really hilly i'm not using the bottom Big gear. I'm mainly in 2 - 4-6

 

[NorthernDave]

It's dead easy.
Don't cross the chain. This is akin to crossing the streams in Ghostbusters and must be avoided at all costs.

Otherwise if you're pedalling like billy-oh and getting nowhere, you need to change up. Or if you can barely make the pedals go round then you need to change down.
If it feels about right, then it probably is.

 

[leedsmick]

If you see me out and about Dave, give me a nod. Cheers