On 03/02/2017 12:17 PM, Wayne Naha wrote:
No, Steve, it doesn't have to be a freewheel at all. The Grand Bois
120mm cassette you found is amazing. I had no idea that such a thing
existed. It really is ideal. I really wasn't relishing the use of a
freewheel, mainly because they don't seem to be made anymore. And
with the Grand Bois I can get an extra cog tucked in back there, which
is nice. The rear spacing of this bike has been the sticky wicket in
the whole 700C conversion project. It made no sense to me to go to
all the effort and expense of ditching the 27" wheel, only to keep the
freewheel. Thanks for the info!
https://www.compasscycle.com/shop/components/hubs/grand-bois-120mm-cassette-hub/
for the hub (currently 32 hole out of stock, 36 hole in stock) and
https://www.compasscycle.com/shop/components/hubs/grand-bois-6-speed-cassette/
for the cassette. "These custom cassettes from Grand Bois are made for
use with the 120mm spaced Cassette Hubs, allowing you to breathe new
life into an older frame. The cassettes uses Shimano 7-speed cogs and
spacers, so 7/8-speed chains must be used. Ratio: 14-16-18-21-24-28"
Mate that with a 7 or 8 speed index shifter and a recent Shimano rear
derailleur and you've got a mostly modern bike.
Couple that cassette up with the proper choice of chain rings, and you
can really make a pretty nice drive train. Here's a configuration that
would tick all of my boxes:
50/34/24 700x32 6 spd 14-28
96.4 63.6 46.3
84.4 55.7 40.5
75.0 49.5 36.0
64.3 42.4 30.9
56.3 37.1 27.0
48.2 31.8 23.1
And also note that thanks to the narrow hub and the flexible modern
chain you could use all six of the sprockets with the big ring and have
no cross-chain angularity issues. Given my basic parameters (high <=
100 gear inches, low on the middle ring ~ 32", low on the granny ~
20-23") this is right there. No monster cliffs to fall off or struggle
to climb up, no zigzagging back and forth trying to eke out reasonable
spacing and no major compromises on range either. Not shabby at all.
Actually, this is the first time I've calculated a 34/50 that made any
sense to me!
On Thursday, March 2, 2017 at 9:46:04 AM UTC-5, Steve Palincsar wrote:
I get the 120, but does it have to be freewheel? Grand Bois makes
a nice new 120mm cassette hub that can fit a five or six speed
Hyperglide cassette (made with 7 spd sprockets and spacers).
On 03/02/2017 09:38 AM, Wayne Naha wrote:
Bill, you are so correct about the sensitivity, II was not
expecting this level of fun. And about finding a 120 mm hub!
But I've got time on my hands to look. Thanks to all who have
responded. That 120mm Grand Bois cassette hub is certainly an
interesting option.
On Wednesday, March 1, 2017 at 11:09:06 PM UTC-5, Bill in Roswell
GA wrote:
Certainly one of the most sensitive places to have surgery!
Having had 3 ankle surgeries over the years.
Wonderful frame, would have to spend a good bit of cash to
get something like that built these days. 700 conversion is
certainly worth going to. Modern brakes have much less flex.
As for wheels, modern rims with machined brake track (Mavic
Open Pro, CR 18 for instance) would be preferred. I like
Shimano hubs because they are easy to rebuild and service
from that period. Downside is finding a 120 freewheel hub
built to a modern machined brake track rim. I'm sure there
are plenty of other excellent opinions.
Cheers
Bill in Roswell, GA
On Wednesday, March 1, 2017 at 11:21:03 AM UTC-5, Wayne Naha
wrote:
This past Monday a very helpful and friendly orthopedic
surgeon kindly harvested a tendon from somewhere inside
my right foot and used it to replace a long missing
ligament that used to stabilize my ankle when walking.
He also scraped out a good deal of osteo-arthritic
buildup that had been limiting the range of motion of my
foot. Recovery has been a bit painful so far. There can
be no weight on the joint for three weeks. So here I am,
reclining on the couch, a little loopy from pain meds,
but so far not watching daytime TV. To pass the time,
I'm kind of daydreaming about doing a 700C conversion to
my 1976 Raleigh Gran Sport. It's a nifty little number
with double butted 531 frame, fork, and stays. Years ago
I installed a Moustache h'bar and Technomic Deluxe stem,
also a new cartridge bottom bracket and a Sugino XD2
triple crank. Now for the wheels. I'd like to be able
to take advantage of the huge variety of 700C tires. And
going to 700C will give me more clearance for a wider
tire, something I definitely want now that I am out in
the country with all the washboard dirt roads. So, any
suggestions on how to proceed? I've never done one of
these conversions.
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