Mark: I was faced with the same upgrade on a couple of bikes in the last year. I agree that the
shifting on the Regina freewheels is not great with the Shimano SIS shifters.
My recommendation: simply replace your freewheel with a Shimano 7-speed unit from the last 15 years
or so. The freewheels with Uniglide cogs shift reasonable well. You should be able to find a whole
bunch of freewheel options from either Ebay, or the marketplace Usenet forum, or from the backrooms
of more established bike shops. The shops don't often know what inventory they have until they dig a
little. For example: I wandered into my local shop and asked about some retro parts. They were able
to cough up 10(!) new Dura-Ace freewheels in boxes. The Dura-Ace freewheels are highly customizable,
in that if you have the cogs, you can start at a 12-tooth
min., and go up to a 32 max., and anything in between. They are also very well made, unlike 99%
other freewheels I have taken apart, or worn out, and they are serviceable.
The best option is to get a 7-speed Shimano freewheel with Hyperglide cogs. The 7-speed (14-28)
Shimano HG37 unit shifts as well as any current cassette cogset. But as you say, you have no
options: you are limited to 14 for the little cog, and 28 for the biggest. Mechanically, this unit
is inexpensively made, and its body is about 3mm wider than a comparable Dura-Ace freewheel, which
can cause problems on many frames.
I have constructed freewheels with the Dura-Ace bodies and the transplanted Hyperglide cogs, which
allows a 12-28 or 13-28 unit. You may want to check if your derailleur can in fact handle a 28-tooth
cog. You can usually cheat on the recommended derailleur ratings by at least 1 tooth with no
negative effects.
"Derek Mark Edding" <[email hidden]> wrote in message
"]news:[email hidden]...
Quoted message said:Hi Folks,
I'm trying to upgrade my early nineties Basso Gap road bike, which has a 126mm rear wheel spacing.
I have a Dura Ace drivetrain on this bike, and Dura Ace SIS-capable bar end shifters.
Unfortunately, the back wheel has a SBI hub with a Regina 7-speed freewheel, and it's incompatible
with Shimano SIS. I can use it with the friction setting on the shifter, but the shifting is
lousy. The chain easily rides on top of the freewheel gears unless you tweak the shifter sightly
one way or the other. It's also difficult to downshift on a significant grade.
I'd rather not scrap this bike and replace it because it's in very good shape, and fits well. I'm
considering two options:
1. Finding a replacement freewheel that is SIS compatible.
2. Frame bending to fit a more up to date wheelset with a SIS-compatible freehub.
For #1, I looked on Harris Cyclery's pages and can only find SIS compatible freewheels that go up
to 28 teeth or larger. The chain wrap on the Dura Ace RD limits it to 27 teeth max. I haven't seen
something smaller so far that is SIS compatible. If there was, I'd be set!
For #2, this is of course more $$$. The wheels I have are very good and I'd rather not replace
them. I'm not too worried about frame alignment issues if I spread the stays though. The Gap frame
has rear wheel position adjusters if it turns out to be slightly off.
Does anyone remember a better solution for this problem?
Thanks for any help.
-dreq
