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