Henry said:I'm planing on using a 38 x 25 as my bottom gear this year, hope it's
enough.
What I don't like about the Shimano 12-25 cassette is the ratios are
too narrow at the 25 end.
12,13,14,15,16,17,19,21,23,25
The jump between the 17 and 19 is a lot bigger than the 23 and 25 in
terms of development.
My idea is to go with
12,14,15,16,17,18,19,21,23,25
and I'll still have my 18.
Anyone see any problem (apart from asthetic) with loosing the 13 in
favour of the 18?
(I'm guessing the 13 wouldn't get much of a look in on the descents
anyway.)
The jump from 12 to 14 may be slightly disjointed due to th eramps not
lining up too well. But its not much of a concern. It will work fine
enough without the 13.
Why hope your 38x25 is low enough? Why not get some very cheap Shimano
9 speed cassettes and build up a cassette with a lower gear. The best
way to make sure the shifting is still good is to just replace the last
cog with a bigger cog. Using cassettes with all loose cogs of course.
Such as the HG50, HG60, HG70, 105, Tiagra, LX, Deore levels. Not the
Ultegra or Dura Ace or XT or XTR cassettes with the riveted together
cogs on aluminum carriers.
Shimano makes a 13-23 HG70 loose cogset. 13-14-15-16-17-19-21-23-25.
Replace the 25 with a 28 cog from a 11-32 9 speed cassette. 11-32
cogsets are as common as bugs. You now have a tightly spaced cogset
with a bailout gear. Or take a 13-23 cogset,
13-14-15-16-17-18-19-21-23 and replace the 23 with a 28 cog. Big jump
on the last shift, but you won't make it very often and when you make
it you will stay in that gear for the rest of the way up the mountain.
Changing the last cog on a cassette is a great way to improve the
ratios the factory forces upon bicyclists. It has no appreciable
affect on shifting because you rarely use that last cog.
