rocketman58 said:"Matt O'Toole" <[email hidden]> wrote in message
Quoted message said:news:<[email hidden]>...
Quoted message said:rocketman58 said:I have a cold forged Ritchey crank that sports 41,30,20 rings.
How's that for compact? Set up with three rings, it still weighs
about 625g. Ya, I know it's not the same "compact" as everyone has
been talking about here, but if ya need real low gears...
...and if you don't mind a little chainsuck...
In my experience (riding for almost 30 years) chainsuck is a product
of excessive drivetrain wear and/or poor maintenance. I have only
sucked a chain one time, and it was due to a worn alloy 28 tooth ring.
I have never sucked a 20 tooth ring, even with a narrow 9spd chain.
I only use steel 20 tooth rings since the alloy ones wear too fast. I
have even used "rings" as small as 18 teeth (adaptors using cassette
cogs) and never had problems with chainsuck.
Two things:
Smaller rings wear faster, because of higher torque and chain tension, and fewer
teeth to spread the wear among.
Second, the further you bend the chain, the longer it takes to bend it back.
This is especially true if the chain is dirty. There's a good reason Shimano
chose 22T for its Compact Drive instead of going all the way down to 20 like
Suntour. They wanted to match Suntour's marketshare-garnering "innovation," but
still keep shifting reliable. This was tested to death by Shimano engineers.
Back in the day when high end mountain bikes all came with Suntour, the Suntour
riders piled up at the base of all the hills, stopped dead by chainsuck. XC Pro
came with steel inner rings that didn't wear much, but they "sucked" even when
brand new and relatively clean. Ritchey even came up with the 2x9 system to
eliminate the inner ring entirely, especially for muddy riding. Middle rings or
larger inner rings can suck too, but the smaller you go, the more prone you
are -- and that's a fact. Note that Shimano has stuck with non-Compact sizes
for their flagship group, XTR.
Matt O.