Feedback Sought on Planned Build - Rear Hub Stealth Commuter

[PublicToilet]

Hi all,

I'm planning to build a new ebike shortly and I'd appreciate any feedback on the design.

I'm trying to make it reasonably stealthy/clean and I understand I'll have to sacrifice some speed and range for that. It's going to be used to commute around 25km return each day over slightly uphill terrain, and I'm mostly wanting the motor assistance for the trip there.

I've tried emailing Grin for advice but I haven't heard back from them yet.

The components are going onto a 2021 Marin Muirwoods, which has a CroMo frame with 29" wheels. The rear dropout width is 135mm and will need to be slightly widened to accommodate the 138mm motor, but I believe that should be fine from my research.

Motor: Bafang G310 Standard Wind
Battery: 36V 10.5Ah Bottle
Controller: V6 Baserunner Z9 Controller
Display: Mini OLED Display and Switch
PAS Sensor: 24 Pole PAS (HiGo Plug)
Harness: Main9 Superharness
Torque Arm: G311 Torque Arm or V5 Universal Eyelet Torque Arm

All components except the battery will be purchased from Ebikes.ca. The battery isn't ideal but suitable options are limited and that AliExpress seller seems to have reasonable reviews. I'll take the obvious precautions when charging it.

I'm unsure which torque arm will fit best on my bike, so I intend to purchase both and figure it out in person. I'm also not certain if the 12mm V5 torque arm is suitable with the 10mm axle on the G310.

I'm not planning to have a thumb throttle as this is unlawful with a motor above 200W in my jurisdiction and I'm risk averse.

Does anyone have any feedback on the above design?

Cheers,
PublicToilet

 

[99t4]

Doesn't the G310 have an actual round 10mm dia. axle that requires the use of a (mounted inboard of the dropout) tabbed washer? Evidently their G311 TA can be used in place of the tabbed washer.

Not sure if it will fit your dropout configuration as some dropout designs have extra flanges or abutments that might impede fitment. And they may lack conveniently located threaded eyelets. Can you post some clear detailed photos of the dropouts (especially the inboard sides)? Possibly the V5 could work also as the distance between the flats should be the same across the inserts (10mm).

"These motors do not have intrinsic flats on the axle for preventing axle spinout. They have a keyed washer that fits inside the forks and has a tab that engages with the bottom of the dropout slot. This gives the same kind of leverage against spinout as you'd have from a large 14mm flattened axle, with the benefit that the motor axle center is in the same location as a normal bike hub, and without the oversized M14 nuts and washers that don't fit inside the lawyer lips. On the downside there is no facility for external torque arms to move the reaction torque further up the fork blade, all the torque is resisted at the dropout slot via these washers.

Most bicycle dropouts have more than adequate strength to resist spinout from the washer tabs. However, if you have a front fork with aluminum dropouts, there is not much margin between the motor torque and dropout failure. For installation on bikes with alloy dropouts, we have a specially made inside torque arm that replaces the left side anti-rotation washer and has an arm that bolts to a fender eyelet. In addition to a regular washer, lock washer, and barrel nut, there is also a thin 1mm spacer washer that is available in the washer stack. This can be placed under the tabbed anti-rotation washer to give a bit more clearance between the side of the motor and the fork, which can sometimes be handy for disk rotor alignment, fitting 9 or 10 speed freehubs, or giving a bit more room for the wide part of the fork blade to not rub against the side of the motor."

From G310-G311 - Grin Kits - Product Info

Otherwise you might be OK with the supplied tabbed washer IF you shim it tightly if there is any slop in its fitment to the dropout surfaces (note the spaces between the washer tab and the dropout faces in the above drawing).

Good on you for searching out quality TAs.

 

[E-HP]

The rear dropout width is 135mm and will need to be slightly widened to accommodate the 138mm motor
Torque Arm: G311 Torque Arm or V5 Universal Eyelet Torque Arm

Does anyone have any feedback on the above design?

Regarding the torque arm, you may want to read the thread below, specifically about adding a torque arm to a rear G311. Two things to note: the member on the thread ended up using the V4 torque arm on the left/disk side of the motor. Adding the torque arm to the inside of the dropout will require spreading your dropouts a little more than you may have planned to, but should be not issue with a steel frame; however, the additional width will require shimming or otherwise adjusting the brake caliper position with spacers or washers.

Can Grin 311 Front Torque Arm Be Used on Rear G310 Hub.?

I'm wanting a torque arm on my bike. Even though it might not be needed, I'd feel better about it. Can a Grin Front Torque Arm 311 Be Used on a Rear G310 Hub.? I notice Grin shows the front 311 torque arm in their website drop-down menu options for the rear G310 kit. But, when I asked Grin...

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