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I intend to upgrade my FireFox Sniper V to electric, by replacing the front wheel with a motorised kit wheel. My question is that the wheels (both) are quick-release: is it safe to motorise this bike.

! - the motorised kit wheel is bolt on type.

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  • The only real issue would be if the axle on the new wheel were a larger diameter than the existing one, and so did not fit the existing dropouts. But this problem is unlikely, as oversized axles are fairly unusual. The standard QR axle is 9mm in diameter. – Daniel R Hicks Oct 12 '15 at 21:12
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    Totally unrelated comment - You need to change your riding habits when on an ebike. It is easy to go faster than normal, so you must bike defensively. Don't ride in the door zone, and scan much further ahead. Do the eyeball-eyeball look at drivers; they always underestimate your approach speed. – Criggie♦ Oct 12 '15 at 21:58
  • @criggie, that is some good know-how, thank you for sharing – user14633 Oct 13 '15 at 2:44
  • Could you specify your location so the advice is more relevant? Some of the attempted answers are trying to guess and this would help. – Móż Oct 15 '15 at 1:04
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Yes, probably and maybe. I'm unfamiliar with your bike model, but I have run my own ebike front motor for a couple years.

To answer your question - the old wheel is quick release, but the replacement one will likely be a bolt-on wheel. It is possible to use quick release adapters, but wheel nuts are more secure and will hold the anti-spin washers better than a QR.

The main problems stem from design of the front forks and power of the motor. As your motor powers on, the torque is transmitted through the axle. Over time the dropouts get chewed out.

What is the wattage of your motor? Anything under 300 watts doesn't have enough impulse power to cause a problem. If you have over 500 Watts then a torque arm will help keep your forks working.

Here's an image of a torque arm - it helps distribute the rotational energy into the fork rather than just through the dropout. Torque arm

Do you have disk brakes? Your motor kit has to have bolt holes to support the rotor in the right place. This is not an issue for rim brakes, but your rim brakes need to be working perfectly to cope with the extra speed and momentum.

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  • that clears all my doubts, my motor is under 300 watts. Also I have rim brakes, i don't intend to cross 25kmph on motor power only – user14633 Oct 13 '15 at 2:48
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Lucky you ;) As for myself, living in New York, USA (Brooklyn,) I know that by United States Federal Law All Ebikes under 750 watts are legal WITHOUT a License, Insurance etc BUT In New York City ALONE, they are currently illegal by city code, to rid on public streets, (Though a Law to revise that, is currently doing the rounds in the NY State legislature.) It's also legal I believe in NY Parks on paths (e.g NYC's Prospect or Central Parks (It's not so easy to find a current definitive standard Ebike guide to post @the moment that is correct for EVERYWHERE in the world, BUT if I find one I will again update this answer to include it) and obviously private 'off road' areas are good too... Rear wheel quick releases axles are not as sturdy as a through axle but for a 500watt or 300w motor, like yours, it should be fine and likely won't need a torque arm either, unlike a front wheel hubmotor setup, in which case I'd advise installation of the Torque arm to support the stress on your forks... About the disk brakes, I Hope you will consider getting brakes with electric motor cutoff switches, they are not that expensive (For Mechanical @least) and when paired with decent rotors 160mm or better 180mm, will really enhance your braking, as your not fighting the motor too and are therefore a quite vital safety feature for an Ebike in my opinion.

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  • Well, I hope the law is revised, and yeah the diskbrake with autocut off is a good addition. Thank You :) – user14633 Oct 14 '15 at 15:30
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    I'm not sure of your budget or how quick you need the components, BUT I personally just bought a set of Zoom Hydraulic disk brakes with E- auto cutoffs built in, with 203mm rotors, for 100 bucks from my supplier in China for my E Endurobike build but that's probably overkill for you, but I'll gladly give you the supplier if you wish (Since my Motor is just a touch bigger than 300w - Or 3000w for that matter ;) and YES obv I've already installed 2 rear torque arms (Motor to output 77v nominal @60amp constant, about 4600w nominal) I kinda NEED em. Good luck on your build :) – ABritInNY Oct 15 '15 at 0:22
  • That would be quiet helpful of you, mentioning the supplier. +China is my neighbor :) – user14633 Oct 16 '15 at 3:23
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Yes, it is safe, because motorized wheel will be firmly attached by the bolt mount.

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  • That clears my one doubt, my other doubt is that the grove on the fork is designed to adapt quick release mechanism and not bolt one, does that create some problem – user14633 Oct 12 '15 at 15:21
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    @yawar No, it isn't. Bolt and QR mounts are designed to replace each other. – Alexander Oct 12 '15 at 22:31
  • @Alexander, that is good to hear. Thank you for clearing the doubt – user14633 Oct 13 '15 at 2:50
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Have you perhaps looked into going with a rear wheel motor or even better a central drive, (Bafang-8Fun- has great affordable models now at different power levels.) that will allow you to really leverage the bikes gearbox with the motor to make it a "Real" hybrid Bike-electric... As it is the speed increase to 20+ mph means you should perhaps look into Hydraulic or mechanical disk brakes with decent rotors, Stopping is EVERYTHING on an Ebike and if you are in city stop -go traffic I think they're better. The law allows upto a 750watt motor (Federally)but a 36v (or 48v) 500w mid drive, I think would be the better solution and perfect power level to still allow you to retain the 'Bike feel.'

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  • Yes I did look into real-wheel drive and central drive, my rear wheel is also quick release type and I don't intend to use central drive. For the brakes your suggestion is very good. And I don't have ebike laws in my cou ntry – user14633 Oct 14 '15 at 11:11
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    Please update this answer to specify what jurisdiction your are discussing. You mention mph, watts, and a Federation, but these give no clue to where in the world you mean. – andy256 Oct 15 '15 at 0:30
  • It would be helpful to link to somewhere those rules are laid out rather "someone on the internet said". – Móż Oct 15 '15 at 1:02
  • I should have specified FULLY rather than just assume that everyone knew that NY meant New York U.S.A. I wrote, I lived in the boro of Brooklyn (Kings County) New York and so I had stated the more liberal U.S Federal E-bike laws which allow upto a 750 watt (1 HP) motor assistance, with speed limited to 20 MPH of throttle assist max (you can legally pedal as fast as your legs are strong, above the 20mph motor cutoff) EU and Australia etc have much lower 250watt max motor size and a 15mph/ 25kph max assist level by Pedal Assist sensors to be a 'Pedalec' bike. NYC has currently BANNED all Ebikes! – ABritInNY Oct 15 '15 at 2:10

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