Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

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ben2401   1 mW

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Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by ben2401 » Apr 02 2021 5:02pm

Checked derailleur alignment and it seems ok, also took out the hanger (aluminum) and it is flat. Using a 10-speed Shimano Dyna-Sys MTB derailleur (RD-M786) with a Shimano SL-MS41 friction/6-speed SIS thumb shifter. Going to use friction mode until I can modify the pull ratio of the derailleur from 1.2:1 (MTB Dyna-Sys) to SIS 1.7:1 using a small piece of aluminum bolted on the lever arm (as done in a German MTB forum so you can use newer Shimano clutched derailleurs with older SIS stuff). From what I can see if the derailleur is aligned properly then I might have to shave down the lever arm a bit without damaging the functionality to clear the hub motor. On my other DD ebike with a Shimano 9-speed non shadow derailleur I clear just fine but it seems that the shadow plus derailleurs don’t have too much room here.
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markz   100 GW

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by markz » Apr 02 2021 5:46pm

I applaud your nice, clear pictures.

Do you have any spare rear derailleur to use?

ben2401   1 mW

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by ben2401 » Apr 02 2021 7:25pm

markz wrote:
Apr 02 2021 5:46pm
I applaud your nice, clear pictures.

Do you have any spare rear derailleur to use?
Have a SRAM X-7 (‘04-ish?) that came with the bike and the corresponding X-7 shifter. Had a stripped b-tension screw that needs a tap and a bigger bolt. Was going to try to fix it and use it but couldn’t find a decent 1:1 pull ratio 6-speed SRAM shifter that was not gripshift. Could’ve just went with any other sub-10-speed Shimano derailleur but got a great deal on a clutched 10-speed Shimano MTB derailleur, all the 9s stuff was sold out/overpriced and thought I would friction shift it with the 6s freewheel which was the largest the dropout had room for. Any indexed shifting would be a bonus and I got lucky and found a 6-speed dual mode friction/indexed Shimano thumb shifter for $10 at the bike co-op.

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MadRhino   100 GW

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by MadRhino » Apr 02 2021 11:42pm

I would solve the problem making a custom derailer hanger, if I would need all those gears. I really can’t see why you need the big ones.
Make it fool-proof, and I will make a better fool.

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by ben2401 » Apr 03 2021 1:02am

MadRhino wrote:
Apr 02 2021 11:42pm
I would solve the problem making a custom derailer hanger, if I would need all those gears. I really can’t see why you need the big ones.
Good idea. Might try a washer but think that a custom derailleur hanger might be necessary. I definitely don’t need the gears but I actually like pedalling along. My other bike is a 2000W DD hub and I have a 1x7 setup with a nice 7-speed Shimano freewheel and a 1989 Shimano XT SL-M732 thumb shifter. I like shifting it just for fun and the stealth aspect and treat it as a 100-200W “assist” to the electric motor.

The 28-tooth and 24-tooth cogs work fine so the bike is mobile at least, but not going to put power to anything because I still need a strong torque arm that I will bolt to the rear brake caliper mount.
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dogman dan   100 GW

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by dogman dan » Apr 03 2021 6:01am

Different design derailleur would fix it. I never saw that one before here. Good pictures! Really helps us when they are so good. Though you might use that low gear occasionally, you may be overthinking it a bit how good your shifter needs to be. What you will tend to do is leave it in one gear, or occasionally shift from one to another of just three gears.

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by MadRhino » Apr 03 2021 8:49am

dogman dan wrote:
Apr 03 2021 6:01am
Different design derailleur would fix it. I never saw that one before here...
The long cage derailer is for the extra large low gear cog, which IMO is totally useless with a motor. It is making a fragile shifting range with a big chain length difference that is hard to tune, and does detune quickly.

Most practical with low power hub build is a 3 spd freewheel with a compact derailer. Most high power builders are going single.
Make it fool-proof, and I will make a better fool.

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by Eastwood » Apr 03 2021 10:14am

ben2401 wrote:
Apr 02 2021 5:02pm
Checked derailleur alignment and it seems ok, also took out the hanger (aluminum) and it is flat. Using a 10-speed Shimano Dyna-Sys MTB derailleur (RD-M786) with a Shimano SL-MS41 friction/6-speed SIS thumb shifter. Going to use friction mode until I can modify the pull ratio of the derailleur from 1.2:1 (MTB Dyna-Sys) to SIS 1.7:1 using a small piece of aluminum bolted on the lever arm (as done in a German MTB forum so you can use newer Shimano clutched derailleurs with older SIS stuff). From what I can see if the derailleur is aligned properly then I might have to shave down the lever arm a bit without damaging the functionality to clear the hub motor. On my other DD ebike with a Shimano 9-speed non shadow derailleur I clear just fine but it seems that the shadow plus derailleurs don’t have too much room here.
My derailer also hit the hub motor when trying to shift to the largest gear 7th gear. I just set the limit screw so I only use 1-6. Since the cable attachment is hitting you could always try a different derailleur.

Just another idea I’m not sure if this would work but maybe put a spacer behind the freewheel so it doesn’t screw all the way flush with the hub motor, maybe that would give you enough clearance.

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E-HP   100 MW

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by E-HP » Apr 03 2021 12:50pm

Maybe just switch to a cheap regular derailleur instead of the clutched type. With a rear hub, you barely shift anyway.

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by ben2401 » Apr 03 2021 4:22pm

dogman dan wrote:
Apr 03 2021 6:01am
Different design derailleur would fix it. I never saw that one before here. Good pictures! Really helps us when they are so good. Though you might use that low gear occasionally, you may be overthinking it a bit how good your shifter needs to be. What you will tend to do is leave it in one gear, or occasionally shift from one to another of just three gears.
MadRhino wrote:
Apr 03 2021 8:49am
The long cage derailer is for the extra large low gear cog, which IMO is totally useless with a motor. It is making a fragile shifting range with a big chain length difference that is hard to tune, and does detune quickly.

Most practical with low power hub build is a 3 spd freewheel with a compact derailer. Most high power builders are going single.
Eastwood wrote:
Apr 03 2021 10:14am
My derailer also hit the hub motor when trying to shift to the largest gear 7th gear. I just set the limit screw so I only use 1-6. Since the cable attachment is hitting you could always try a different derailleur.

Just another idea I’m not sure if this would work but maybe put a spacer behind the freewheel so it doesn’t screw all the way flush with the hub motor, maybe that would give you enough clearance.
E-HP wrote:
Apr 03 2021 12:50pm
Maybe just switch to a cheap regular derailleur instead of the clutched type. With a rear hub, you barely shift anyway.
My P2 with a 9-speed XT derailleur has no clearance issues (with basically the same motor and 7 speed Shimano freewheel) as can be seen in the picture... the old style like this one had more clearance because the cable loops around and pulls on the bottom. The newer Shimano “Shadow” and “Shadow Plus” (clutched) has a low-profile design that has the cable pulled from behind rather than below. The lever travels in a very different area.

I know it is totally unnecessary but I had to buy a derailleur and all the cheap stuff was sold out or no sales. Got a great deal on the XT RD-M786 and thought a clutched derailleur would be nice because they are silent (they eliminate chain slapping). Basically a bit of bike bling to combine with the older stuff I found. Wanted a bit of a challenge integrating a brand new clutched derailleur with a six-speed freewheel and vintage Shimano SIS thumb shifter. Couldn’t even find any decent used 9-speed stuff around here (the last Shimano standard that works with everything, they changed the pull ratio on the 10-speed MTB stuff) that wasn’t insanely overpriced for worn out stuff.

When I started planning this full-suspension conversion I seriously considered single-speed or three-speed, but saw that a no-name SS freewheel was the same price or more than a good old Hyperglide Shimano SIS freewheel. I also saw that I would still need a tensioner negating the clean look. Three-speed stuff seemed even harder to find. Is friction shifting the only option for three-speed? Would work just fine. I ordered a mid-cage (shortest available) RD-M781 (non-clutched) as the 14-28T MF-TZ20 Shimano freewheel is pretty narrow range for any modern derailleur and they didn’t actually have stock and offered me a 786 (clutched) long cage for the same price. Don’t need the capacity of this derailleur but it should work nicely and quietly if I can get it to clear somehow.
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dogman dan   100 GW

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by dogman dan » Apr 04 2021 6:30am

There you go, it was just the wrong design for use with a motor. Lots of em out there with different, more compatible design. I have in the past, had to put a spacer washer under a freewheel to use the last cog on the freewheel. The chain and derailleur just hitting the allen head bolts on the motor. But in this case, a different derailleur the best solution.

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by dogman dan » Apr 04 2021 6:30am

There you go, it was just the wrong design for use with a motor. Lots of em out there with different, more compatible design. I have in the past, had to put a spacer washer under a freewheel to use the last cog on the freewheel. The chain and derailleur just hitting the allen head bolts on the motor. But in this case, a different derailleur the best solution.

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Re: Rear derailleur cable attachment lever arm hits hub motor gears 3-6 on six speed freewheel.

Post by ben2401 » Apr 10 2021 9:21pm

dogman dan wrote:
Apr 04 2021 6:30am
There you go, it was just the wrong design for use with a motor. Lots of em out there with different, more compatible design. I have in the past, had to put a spacer washer under a freewheel to use the last cog on the freewheel. The chain and derailleur just hitting the allen head bolts on the motor. But in this case, a different derailleur the best solution.
FYI I got it to clear with two mm-or-so thick stainless washers. Still looks like more than 2/3rds of the threads are being used and the b-tension tab is just long enough to work fine. Lots of clearance for full travel of the cable clamp. With one washer it was barely touching at one point. Would work if it it had to with one once it wore in. Going to replace the frayed cable and experiment with getting indexed shifting working by changing the cable attachment point and thus the pull ratio from 1.1:1 10s Shimano MTB to Shimano SIS 1.7:1. Actually shifts pretty nice in friction mode, would be happy with how it is. The clutched derailleur is super quiet and the 6s Shimano HG freewheel is very smooth. Using a SRAM PC971 9s chain and it works fine in both. A real Frankenstein setup but I like it.
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