Cruiser + Front Hub Motor - Safety Question?

high_desert_mud

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I'm doing a relatively low-power cruiser conversion for my mom. she's not an experienced biker by any stretch, and will be using the cruiser year-round, including towing a small trailer (kids; attaches at rear dropout). pavement or gravel path only.

I'm wondering - does this create a crash risk from unexpected spinout / traction loss on front (cornering, wet pavement)?

Thank you for your thoughts!


DETAILS:

For reasons, I would prefer to do front drive:
balance of bike when picking up (the battery must be on the rear rack due to space) ability to use IGH

Kit:
I will be doing a BB torque sensor, versus throttle or crank-rotation sensor, which will hopefully reduce 'sudden power' surges that could exacerbate this. Most likely Grin eZee or G301, possibly GMAC (software-limited on power) to support regen braking.
 
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honkinunit

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Unless you are truly interested in doing a science fair project, you are much better off just finding your mom a used mid-drive commuter/trekking bike if you are concerned that she can't operate a throttle. Most of the aftermarket BB torque sensors are garbage, and the odds of getting it all to work together smoothly with a front hubmotor are low.
 
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high_desert_mud

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excellent point, and true. For this reason, I'm using Grin/ebikes.ca stuff - while not cheap, I have heard it works quite well**. It is certainly well engineered and I've found them very knowledgeable and helpful. For eMTB the low CG, low overall weight, and no change to unsprung weight - certainly means integrated BB motors have a big advantage; however for a cruiser, none of those come into play (especially not the biggie - unsprung weight - I don't think she'll be doing any ~ springing :) )

Her bike won't have a manual throttle; maybe to rephrase my question:
  • a cruiser already has weight distribution further rear than types (less available traction in front)
  • adding motor thrust reduces the available traction for cornering on whichever wheel
  • she will not accelerate quickly, but any acceleration reduces front wheel available traction (hopefully not that relevant for cornering)
  • for (non-avid bikers, even more so) loosing front wheel traction is much harder to recover from than rear-wheel

So as a practical matter, in a "heavy-rear" bike, with a low-thrust front wheel, in "good" but "all year" conditions (eg, some wet road), do folks see significant washout of front wheel?
 
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high_desert_mud

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** from last post == I'm using a Grin GMAC/Phaserunner/CycleAnalyst on my BigFatDummy - but only occasionally (I swap the whole fork) so I have not installed a thrust sensor to experience the PAS. But the overall kit is great, and seems to have a great reputation.
 

matt4x4

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Front hubs need Torque Arms on both sides! You mention its low power, so can assume 250W, still good practice to install 2 ta's.
Ideally you want a steel front rigid fork for its stiffness.

Grintech www.ebikes.ca in Vancouver Canada are the leaders in the ebike industry!
 

richj8990

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"Hub (front) motor, thousands of miles and no issues...including trails and logging roads...but a hub motor is 'obviously' not the way to go for MTB"?

Sounds like you are of two minds on the topic...which alternate every 10 seconds.

I recently got a decent chunk of 'free' money to spend on whatever I wanted, thought about a mid-drive conversion, or a whole new mid-drive e-bike...

And then about a month ago I caught up with a group of experienced riders 1/2 way up on a fairly steep hill. Enough room to say hello and pass them. It took the fastest guy about 2 minutes to catch up to me on his non-ebike, and the rest of them were way behind. To put this in perpective, this was with a $280 Chinese off-brand bike, front hub motor, and a 75% worn WTB Ranger 2.8 with mediocre knobs that was on its last legs. I just completely blew them away. I didn't really mean to, I don't want to be "One of those" E-bikers and I even told them that at the top and they were cool with it.

From the very limited data I have on ebike climbs vs. XC pro non-ebike climbs, the front hub drive, with the right type and width of front tire, can climb almost as fast as the non-ebike climbing KOM by a pro racer, usually within 25% or less, sometimes faster than the KOM. So please don't tell me hub drives don't belong offroad. I've had the money to buy a mid-drive for a while and I really don't see much point in doing that right now, I'm perfectly happy climbing offroad with a front hub drive. And that's with the front hub ebike more or less dedicated to offroad, now that I have a 24 lb XC non-ebike for pavement.
 

J.B. Weld

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Most people don't want to muscle a 20lb wheel over obstacles, also they're illegal on most trails.
 

Jack7782

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Stability and balance on and off the bike - a low step frame is your best setup for towing a trailer with kids. I would think that a throttle would be useful to get started too. Here is my street bike, an IZIP Vibe+ that features a mid-drive - and has an optional throttle kit, that I don't have.
IZIP Vibe+.jpg
 
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matt4x4

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I have been using a front dd hub, typical 9C clone, and only using one t.a. and its been fine, even in the winter, snow and ice. My t.a. is just a steel plate I cut notches to fit, and using hose clamps to secure. Not a single problem!

Ideally you do want two t.a.'s installed, and for a front hub, ideally a steel fork. But my setup is so weak, 36V 26A that there have been no issues whatsoever. I believe my fork is more then likely alum.

Front hub
- low power setups
- low speed setups
- ta's are a must with any hub front or rear
- easier to fix a flat tire
- 'unique' handling in some circumstances - like lifting the front up to pop a curb, going around a corner on snow/ice, the usual front drive problems with ebiking.

Rear Hubs
- way more ideal
- two ta's
- can use way more power if you choose to, within the law of course LOLOLOL
- better handling
- more of a problem replacing a flat, but not a big deal once you have done it a few times LOLOL I've done it many a times LOLOL

Never install a higher powered hub motor on a front fork, its not a wise idea at all.
 
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