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I have a hub motor 250w e bicycle with a 7.8 mah 36v battery (https://felidaeelectric.com/maven-e-bike-n/). This ecycle has both pedal-assist and a throttle.

Using it for school commute and will be parked in a common area with a physical rear wheel lock when parked. The bike does not have a key lock on the throttle or the instrument console.

So the concern here is people fiddling with the bike when parked - turning on the power and giving throttle. Although the rear wheel is locked, the motor will still be powered and will try to do work and move the wheel. Can the motor/controller be damaged in this scenario?

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  • 1
    Are you saying the throttle is completely independent of the pedaling action? You can accelerate on the bike without pedaling?
    – Kyralessa
    Dec 11, 2022 at 8:14
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    Can you remove the battery and carry it to class? Or leave the battery at home and ride like a normal bike without assist?
    – Criggie
    Dec 11, 2022 at 9:57
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    This does not sound like an "e bicycle". More like an "e motorcycle".
    – juhist
    Dec 11, 2022 at 10:01
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    @juhist In the USA, so-called “Class 2” eBikes can operate up to 20 mph and have a throttle that applies power without pedaling. wired.com/story/guide-to-ebike-classes Classes 1 and 3 require pedaling to activate assistance up to 20 mph and 28 mph, respectively.
    – Paul H
    Dec 11, 2022 at 13:07
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    @Criggie That's not always an option. Some new e-bikes have the battery built in to the downtube, only removable with a workshop. Some conversion kits put the battery in a frame bag, but then hard-wire it.
    – Chris H
    Dec 12, 2022 at 13:41

2 Answers 2

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I'd be more worried about mechanical damage. Assume the driven wheel is locked up, and the lock prevents the wheel from rotating by blocking one spoke. Those motors have a lot of torque and applying that all to a single spoke (worst case) is a lot of tangential force where the nipple meets the rim, or at the bend in the spoke. If locked near the rim the spoke could slam into the lock, as the wheel gets some speed up, but nearer the hub it would still have to deal with the stall torque.

To put some numbers on it, a low-end 250W motor can deliver 40Nm of torque. With a lever arm of 10cm (holding the spoke still near the hub) that's 400N, or the equivalent of hanging 40kg off the spoke. Even if you'd lift a heavily laden bike by one spoke, the lacing pattern distributes lateral loads across the neighbouring spokes. There's nothing to do that in rotation.

Motor controllers should be able to handle stalling, at least until the tamperer gets bored.

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  • Spokes can’t be loaded sideways, that’s why they are installed at an angle so that 2 or 3 spokes cross each other. Accelerating from a standstill in the easiest gear (especially in combination with the motor) will produce much higher torques.
    – Michael
    Dec 12, 2022 at 12:09
  • @Michael I'm thinking of a lock holding a wheel in place by one spoke. Precisely because they can;t take side loads in use, they shouldn't be subjected to side loads in storage. I hastily turned what was going to be a comment into an answer, and it needs an edit.
    – Chris H
    Dec 12, 2022 at 13:27
  • ... Also before coffee I couldn't think of the word "tangential" which would have made more sense
    – Chris H
    Dec 12, 2022 at 13:35
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    Oh, if there is a lock or some other object stuck between the spokes then I totally agree that it could cause damage to spokes.
    – Michael
    Dec 12, 2022 at 14:13
  • Sorry @Michael, I shouldn't rush answers first thing (but it was just slightly more than a comment)
    – Chris H
    Dec 12, 2022 at 14:46
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The motor of the normal 25 km/h E-bike will not apply any power on a standing bicycle. You need to move the bicycle by rotating the pedals to get the power. My E-bike also has the "push mode" when it would apply the power on a standing bicycle, but only while the "push mode" button is kept depressed by the hand.

If you switch on the controller of the standing bicycle (not yours), it simply self-powers off after some time out.

Near all E-bikes sold in Europe would behave as described. It may be various unusual models worldwide that would behave differently.

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    Yours is presumably built to European specification (with push mode very slow). The OP hasn't specified a location that would make this applicable, and a lot of add-on kits don't meet European spec. I see enough being ridden around here on a throttle, where it's illegal but there's no enforcement.
    – Chris H
    Dec 12, 2022 at 9:54
  • All E-bikes for sale in Switzerland would behave as here described. No pedals, no extra power and push is 6 km/h max and only while the button is held depressed.
    – nightrider
    Dec 12, 2022 at 10:00
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    Yes, Switzerland, the EU, and the UK (etc.) require that for all electric bikes sold, and legitimate sellers meet the requirements. Now go on Amazon and look at retro-fit kits. The vast majority are illegal for use on public roads in most countries. But they're really common. The US has multiple legal classes (actually the EU does too, but the 40km/h class that's neither bike nor motorbike barely exists in practice)
    – Chris H
    Dec 12, 2022 at 10:06
  • -1. The OP tells us this bike has a throttle, therefore an answer that assumes it doesn't is both unhelpful and irrelevant.
    – Chris H
    Dec 12, 2022 at 13:38
  • It is not clear that the OP calls the "throttle". There are + - buttons on the most of E-bikes just to control the level of assist so I assumed, somebody turns the controller on and cranks + to max assist. Also, 250W looks for such an E-bike unusually low power.
    – nightrider
    Dec 12, 2022 at 14:26

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