Quoth Jerry Moos:
>I've just gotten my new Bates frame built up sufficiently to road test
>(still need to install racks, mudguards, etc.). This is the first bike I've
>actually built up with a triple (finally conceding to age). I've used a TA
>Cyclotourist triple 52-38-28, Campy Rally RD, Simplex SLJ Triple FR, and
>Sachs Aris 13-28 6-speed FW. Even with the long-cage Rally, when I shorten
>the chain enough to just keep it from going slack on the 28x13, it is very
>difficult to shift onto the 28T rear cog when on the 52T chainring.
Make the chain longer, you should never, ever, under any circumstance
use the 28 13 combination on such a gear setup. The fact that the
chain droops in the no-no small/small gear is of no importance.
>More
>annoying, although shifting down to a smaller chainring works smoothly, and
>shifting between the 52 and 38 in either direction is no problem, it seems
>completely impossible to upshift from the 28T chainring to the 38T middle
>ring. I always wind up having to shift from the 28 all the way up to the
>52, then down to the 38. Normally, I'd try to toe out the back end of the
>FR to try to lift the chain a little better off the small ring, but one
>cannot do this except to a tiny extent, due the the Cyclotourist crankarm's
>infamous lack of FR clearance, i.e. if you toe out the back of the FR, it
>will hit the crankarm when on the large ring. It was exactly this feature
>of the Cyclotourist that caused TA to lose their early dominance in mountain
>bikes to the Japanese.
>
>Am I doing something wrong, or is this just an inherent limitation of the
>Cyclotourist/ Simplex SLJ combo? Anyone have a guess how large a small
>chain ring I'd have to go to to shift smoothly (or at least shift) up to the
>38T middle?
Actually, the SLJ triple is probably about the best possible derailer for this, but that's a basically very awkward setup, most especially for a Cyclotouriste.
The problem is that there's too great a difference in sizes between the middle and large chainring. The large chainring limits how low you can mount the front derailer, and upshifting wants the inner cage plate to be as close above the middle ring as it can be without rubbing.
Most "triple" type front derailers are optimized for a 10 tooth difference betwixt the middle and large ring.
The Cyclotouriste makes a great wide-range double (I love the 50-28 I've got on my Hetchins) and it also works quite well as a (yuck!) half-step-plus-granny rig, but the combination you have selected, while it may give good gearing on paper, will never shift well, no matter what you do.
If you're really set on those ratios, my advice is to get a modern 130/74 "road triple" crank and use one of the TA "intermediaire" 38 tooth chainrings, the only ones available in that size that feature shift-assist pins and ramps. This would work, though not shift quite as well as a stock Shimano 52-42-? setup. We stock the chainrings.
Sheldon "Some Things Were Not Meant To Be" Brown
Newtonville, Massachusetts
+----------------------------------------------+
| Certainly the game is rigged. |
| Don't let that stop you; |
| if you don't bet, you can't win. |
| --Robert A. Heinlein |
+----------------------------------------------+
--
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com
Useful articles about bicycles and cycling
http://sheldonbrown.com