Hi,
I have many questions about Shimano freehubs, cassettes and
chain/chainwheel compatibilities.
First of all, let me say that today I received a Regina 12-31
freewheel that I purchased for using with an older (1988) Scott
Boulder MTB that I use as a winter-touring bike. I purchased it last
year and believed that since the rear cluster was 6-speed, and that it
was manufactured in 1988... that it used a freewheel mechanism. My
maintenance to the "freewheel" bearings/races was to simply dribble
oil into the crack around the bearing race while spinning the
sprockets. Today, when I removed the axle, bearings and caps to remove
the "freewheel" I found that my Shimano PR-1 had no where to fit... so
I headed to my LBS. When I handed the wheel to the extremely friendly
shop proprietor he immediately grabbed two chainwhips. "Wait a
minute", I said... "won't that just cause the individual sprockets to
slide off". He continued on, pulled off the cassette, then he grabbed
the 10mm allen key... that's right when I knew that I screwed up
buying the freewheel that had arrived today. Since this particular
freewheel was apparently part of a "Campy group", I had to pay QUITE a
lot of money for it. Anyways...
The reason that I'm wanting to change to 7 speed is that I recently
purchased a set of cowhorn bars and the clip-on aero bars also, so
that I can fight the fierce north wind this winter from a more
aerodynamic position. Christmas day 2003 found me on this same bike
riding due north on sr123 in Michigans Upper Peninsula. Four inches of
new snow fell the previous night and in the morning as I headed north
on the unplowed roadway, in an UPRIGHT position, with a temperature of
17 degrees F, the north wind was blowing so hard that I could barely
move forward. This REALLY impeded my progress. I've been planning
another tour for this winter and I'm trying to be more
prepared/practical based on my experience from last years 600 mile
winter trek. BTW... last years ride was my first ever taste of winter
riding.
I purchased a NOS set of Gripshift CX-DT 125 7-speed shifters, so
that my hands do not have to touch any cold metal bits. Also, my
present 13-30 configuration could be improved upon as I have not been
getting all of the speed that I could, from the 13 tooth... and a 31
tooth would give my old knees a slight bit more relief on the major
climbs (I really am a sissy!).
Oh yes... my questions. Ok... my LBS mechanic told me that the 13
tooth sprocket/lockring on my cassette is as small as I can use (no 12
tooth)...
So, I apparently seem to need a 7-speed freehub-body that takes the
non-sprocket type of lockring... but I'm running a 46/34/24 non-ramped
chainring set and I'm using a Sachs PC-80R chain. I do not believe
that this setup is compatible with HG (hyperglide) cassettes, which to
my knowledge are the only thing available in 7 speed that is anywhere
near what I want. I believe that I'm limited to 11-28 also.
Another thought is that I may be able to keep my present 13-30
cassette and just limit the rear deraileur mech to shift on these 6
sprockets (is that the best way to deal with all of this? More speed
and easier climbing would be nice, but it's not everything... I just
want to get this bike ready and if the necessary
cassettes/freehub-bodies are not available, then I'll do what I have
to do).
ANY help is very much welcome and appreciated.
Owen