Reading several comments centering on chain friction increases from
excessive chain angles running across to the small gear cluster cogs,
increases to the point where many feel the small or in some cases the
large cog are avoided.
I get the same rrrrrrrrr feeling -the wear on chain and gears running
downhill in high is unacceptable given the short term result.
And I have an old bike with a 3S axle setup for a ten speed-5 cog rear
cluster. But the other posters can't be running the same setup so I
get the idea the problem is more general than specific to the 3S/5cog
rear cluster upgraded to 3S/8cog rear cluster.
Everything on the rebuilt sport tourer works but not the chain angle to
the rear cluster small cogs from the 53CR.
Does a triple CR solve or ameliorate the angle/friction wear problem?
Can a triple be shimmed to reduce the angle to acceptable no chain
grind levels when running a new chain.
In getting around to solving the problem (one at a time, right?), I
thought of the Sierra Club's touring guide wherein an "Alpine
Triple" is described: two hi tooth count CR's, 54/47?/X for a close
ratio transmission. The 54 gets shimmed out a wee bit more for
zzooooooooooooooooommmsplatt following the UPS trucks down the
inter-coastal bridge. Odd, before I thought of the Alpine triple as an
uphill setup.
The experienced LBS technician's know how to set this up with a 2 CR
or 3CR/alpine and critique?