Join Date: Dec 2005
Bikes: 1982 Schwinn Super Sport S/P, 1984 Miyata 610, 1985 Panasonic LX 1000, Centurion Pro Tour 15 1983
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Originally Posted by masi61
I'm thinking that since there are 7 cogs, then it would make sense there would be 6 spaces between those cogs.
If you've noticed, the cog spacing between your smaller cogs (H) is thicker. I really didn't have the dimension committed to memory but 3.0 sounds right. The larger cog spacers (L) are thinner 2.8mm. I think what you're trying to do is interesting. I have no direct experience with it but am eager to know how it turns out.
I was in a rush when putting up the OP. This morning clarity is upon me.
1. The hypothesis in the original post, i.e. that 7 speed perfection might be possible with the correct spacers was flawed...because of the current mix of Suntour 7 speed shifter with Shimano
RD. I had neglected the issue of shifter cable pull matching to RD movement in response to that cable pull.
2. The corrected hypothesis: With Suntour 7 speed shifter, Suntour indexing RD and Shimano HG cassette, indexed perfection may well be attainable with a custom cassette with each sprocket spaced correctly center to center
--HG 7 speed sprockets are 1.85 mm wide.
--HG 7 speed spacers are 3.15mm wide.
--HG 8 speed spacers are 3.0mm wide.
--HG 7 speed c-c width is 5.0 mm.
--Suntour 7 speed c-c width is email@example.com(low) and firstname.lastname@example.org(high).
Originally Posted by Sheldon Brown
Theoretically it should not work because Shimano systems use more cable travel per click than Sun Tour does (and less than Campagnolo)
Generally, you need to use the same brand of shifter as the rear derailer to get the correct travel.
That the Suntour 7 speed shifters, Deore RD and HG cassette index very well I take no credit for working out. I was able to google several past posts from reliable voices which reported that Suntour 7 speed shifters, Shimano 105 RD's and either Sachs or Shimano freewheels/cassettes indexed fine.
Now that I am custom cassette enabled, and have managed to get my hands on several 3.0 mm 8 speed spacers (no easy task!), testing the hyothesis is on hold until I can locate a Suntour indexing RD capable of wrapping 35 teeth in order to handle the 48-38-28 front 13-28 HG rear. If anyone has one, please PM me.
Now that I've thought it through, I'm pretty damn optimistic.
Last edited by mrmw; 12-31-06 at 01:48 PM.