Going backwards. 7 sp freewheel to 6 sp,
02-13-20, 01:34 AM
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Going backwards. 7 sp freewheel to 6 sp,
This is an ebike issue. I've got a 135mm motor/hub that was machined incorrectly to be 137mm. I have adjusted the spacers under the freewheel to make it 135mm, but the small gear is too close to the frame. Don't want to spread the frame.
How about a 6 speed freewheel?, They should be thinner? I'll need a 6 speed shifter too? Will the derailleur motion be correct with the new shifter, or does that need to be replaced too?
How about a 6 speed freewheel?, They should be thinner? I'll need a 6 speed shifter too? Will the derailleur motion be correct with the new shifter, or does that need to be replaced too?
Last edited by Doc_Wui; 02-13-20 at 01:39 AM.
02-13-20, 07:40 AM
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Depends on the freewheel. Some SunTour freewheels used threaded cogs in the outer two positions so you could remove the smallest and still have one threaded cog to retain the rest. Or you might be able to grind the frame where the small cog interferes; not recommended but doable. I've done it. We probably need photos to better judge. Index shifting could be affected but friction shifting would continue to work with the limit screws adjusted. A lot to consider but probably not insurmountable.
02-13-20, 08:18 AM
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Shimano 6-speed and 7-speed freewheels differ in width by only about 3 mm. If that's enough then it will work. You will need a 6-speed shifter but indexing 6-speeds are rare so you may need to use friction shifting. However, Sun Tour's (now very rare) Ultra-6 freewheel has the same spacing as a Shimano HG 7-speed freewheel and is even narrower than a standard 6-speed. It should work with your current shifters if you can find one.
02-13-20, 09:16 AM
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Unless the frame is so rigid it's difficult to spread, I wouldn't worry about spreading 2mm.
02-13-20, 11:05 AM
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Appreciate the feedback!.
It's a 20" folder frame with short chainstays and built in rear rack, so it's very rigid. My Shimano 7 speeds are 13.4mm wide. I believe 3 mm would do it.
It's a 20" folder frame with short chainstays and built in rear rack, so it's very rigid. My Shimano 7 speeds are 13.4mm wide. I believe 3 mm would do it.
02-13-20, 11:25 AM
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I'm totally unfamiliar with "electrified bikes", but is there a spacer on the NDS that could be shortened a couple mm?
02-13-20, 11:42 AM
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Here's the drive side. I had to take 2-3 mm off one of the spacers.
02-14-20, 03:45 PM
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It's in. Shimano MF-TZ500-6 14-28. Comes in at 31.8 mm, vs 34.1mm for a Shimano TZ-500-7, and 2.3mm was more than enough for the chain to clear the dropouts. The SIS 7 speed barrel shifter works fine on the test stand. stopping at 6. I ordered a 6 speed trigger model though.
