Cassette: Total Tooth Capacity vs sproke range.

[mattrixdesign2]

Can someone just clarify something for me?

Currently have a kids CX bike (Dawes Espoir), Rear Mech is an Altus (MTB style?) and the shifters are Shimano 2300 (Road - Drop bar).

The rear cassette is 8 speed, 11 to 30 teeth. I want to replace the Rear mech, looking at some Sora options it states

ShortCage: 37 tooth total capacity, rear sprocket size range 11-32T
MediumCage: 41 tooth total capacity, rear sprocket size range 11-32T

So either of these would be suitable as both are in the 11-32 Tooth range? Where does the 37/41 tooth capcity fit in? I would be more inclined to get the shorter cage for extra ground cleanrance, but don't fully understand the tooth capacity.

 

[hamster]

Tooth capacity is the amount of chain it can wrap between loosest (small-small) and tightest (big-big). So you take the front (say 50/34) and rear (11-30) differences and add them: 16+19=35T.

Typically Shimano are very cautious and you can go a couple of teeth extra.

 

[mattrixdesign2]

Right so based on that I need to know the number of teeth on the front two chain rings!

Will count them tonight.

Thanks

 

[Deleted member 24574]

Tooth capacity is the amount of chain it can wrap between loosest (small-small) and tightest (big-big). So you take the front (say 50/34) and rear (11-30) differences and add them: 16+19=35T.

Typically Shimano are very cautious and you can go a couple of teeth extra.

+1

I have run shimano 3 teeth over spec with no problems.