Does anyone know, or know of a reference to, the pull ratios for Shimano 7-speed flat-bar shifters, especially including the modern grip shifters like the SL-RV400?
Older 7-speed grip shifters ( eg Nexus ) are covered at
Sheldon Brown, and those seem to differ ( approx 4-5mm per gear ) from Shimano 7-speed trigger shifters ( 2.9mm per
this google spreadsheet ). Another way of stating my question would be, does anyone know of a modern -- available for purchase new -- 7-speed flat-bar shifter that can be used to replace a 7-speed Nexus grip shifter ( p/n SB-7S40 )? I installed an M315 trigger, and it is not compatible.
Back story, if of interest. I am restoring a
shaft-drive IGH bike that I rescued. Almost all of the components it came with were junk and it was in poor cosmetic condition, so I stripped it, sandblasted it, painted it, and rebuilt it from bare metal. The Nexus grip shifter that I removed does not pull any cable, so I can't measure anything useful from it. I installed the aforementioned M315, and it shifts into 7 different gears, and those gears are measurably-distinguishable from each other but only just barely -- nowhere near the ~250% total gear range that ought to be available.
The manufacturer of said bike is long defunct, as far as I can tell, and didn't make many when they were around. There is just about zero information on the internet, that I've been able to turn up. The model number of the hub does not match any that I've found online, so I think it was specific to this shaft-drive installation. I mention this because I cannot be sure that the Nexus shifter that I removed from the bike was either OEM, or that it ever worked correctly.
Thanks in advance.