What size torque arm do I need for this hub motor??

Hi all, loving the site so far loads of good info!

I have however hit a snag, I am about to order http://www.ebay.co.uk/itm/201694028175?var=501469307840 this kit. It does not seem to state anywhere the axle diameter, I am aware there are 12 and 14 size torque arms available and I would love to be able to order the torque arm with the motor and not have to wait for the motor to arrive to measure it then order the arm. I obviously hate waiting as much as the next guy

If anyone has a definitive answer it would be much appreciated! Thanks

Hi all, loving the site so far loads of good info!

I have however hit a snag, I am about to order http://www.ebay.co.uk/itm/201694028175?var=501469307840 this kit. It does not seem to state anywhere the axle diameter, I am aware there are 12 and 14 size torque arms available and I would love to be able to order the torque arm with the motor and not have to wait for the motor to arrive to measure it then order the arm. I obviously hate waiting as much as the next guy

 

If anyone has a definitive answer it would be much appreciated! Thanks

Yup, you did hit a snag, the item in the link has been removed.

Yup, you did hit a snag, the item in the link has been removed.

I dont think so? I just clicked the link on my phone and it took me straight there? Its one of the common 1000w 48v ebay kits, im pretty sure the axle is 12mm but i would love to hear that from someone who actually has one

Strange one,,,,,, I just get,,

This listing (201694028175) has been removed, or this item isn't available. Please check that you've entered the correct item number Listings that have ended 90 or more days ago won't be available for viewing.

Strange one,,,,,, I just get,,

This listing (201694028175) has been removed, or this item isn't available. Please check that you've entered the correct item number Listings that have ended 90 or more days ago won't be available for viewing.

http://ebay.co.uk/itm/26-250-1000W-Electric-Bicycle-Conversion-E-Bike-Front-Rear-Wheel-Kit-36-48V-New-/201694028175?var=&hash=item2ef5e6a18f%3Am%3AmiF2V0BYvsYcK0U-aMmVjdQ&_trkparms=pageci%253Aa917a312-ea5f-11e6-9fa0-74dbd180380d%257Cparentrq%253A0615083615a0a6a8eee4e355ffa287ff%257Ciid%253A1

There that should work, i dont know why it wouldnt show up for you it works for me, anyway its the 1000w 48v Rear im wondering about. Cheers

Why not just buy one of each to avoid disappointment. You'll only be down eleven quid on the unused one.

http://www.ebay.co.uk/itm/Torque-Arm-for-Electric-bikes-e-bikes-and-Pedelecs-/252680077959?var=&hash=item3ad4e80287:m:mzmjnRvUM0OWnNGXCSPZWHA

I've used these ones from Cyclezee before, and they really are top quality torque arms.

There's more than one type of motor in that listing. The big direct drive motors are normally 14mm x 10 mm and the smaller geared motors are normally 12mm x 10 mm.

Yeah I know I'm wondering about the 1000w rear, so you reckon that would be 14 then?

I've the same size motor on one of my bikes.

I've the same size motor on one of my bikes.

 

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Nice torque arm arrangement, so its definitely 14mm then, did you have to file your dropouts at all or did it just drop in? Seen a few vids where people had to file a bit off the dropouts for the axle to sit flush with the frame

Nice torque arm arrangement, so its definitely 14mm then, did you have to file your dropouts at all or did it just drop in? Seen a few vids where people had to file a bit off the dropouts for the axle to sit flush with the frame

I didn't build it mate. I just bought it.

I'm happy to go and measure up whatever you'd like me to though. Alternatively, you could ask the guy that built it. I'll pm you the info.

There's more than one type of motor in that listing. The big direct drive motors are normally 14mm x 10 mm and the smaller geared motors are normally 12mm x 10 mm.

Just to add to that Dave, to give an example of where a motor doesn't fit the 'normally' description.

My old MAC motor was a geared rear hub and that had 14mm axles.

Alas, vendors aren't very forthcoming with product dimensions in their listings

Edited February 4, 20179 yr by Fordulike

Nice torque arm arrangement, so its definitely 14mm then, did you have to file your dropouts at all or did it just drop in? Seen a few vids where people had to file a bit off the dropouts for the axle to sit flush with the frame

Yes, but don't go overboard. The less snug the axle is in the dropout, the more you're relying on the torque arm to stop the axle twisting out. Use a Dremel with a fine grinding stone attachment, or a fine hand file.

I found I didn't need to file the dropouts when I had a 14mm axle.

Hi all, loving the site so far loads of good info!

I have however hit a snag, I am about to order http://www.ebay.co.uk/itm/201694028175?var=501469307840 this kit. It does not seem to state anywhere the axle diameter, I am aware there are 12 and 14 size torque arms available and I would love to be able to order the torque arm with the motor and not have to wait for the motor to arrive to measure it then order the arm. I obviously hate waiting as much as the next guy

 

If anyone has a definitive answer it would be much appreciated! Thanks

I don't have an answer to that question but wondered why you needed a 1000w motor...an ungeared one at that... in the first place. I had a 500 watt ungeared (i.e. direct) motor ordered in my ignorance from the US years ago. It has less torque than a later 350w geared bafang. It will be mighty heavy as mine was and your 48volt battery will need to be pretty hefty too if you want a reasonable range. Reputable motors like Bafang have all their dimensions on line so you don't end up with a motor too wide for your frame.

I don't have an answer to that question but wondered why you needed a 1000w motor...an ungeared one at that... in the first place. I had a 500 watt ungeared (i.e. direct) motor ordered in my ignorance from the US years ago. It has less torque than a later 350w geared bafang. It will be mighty heavy as mine was and your 48volt battery will need to be pretty hefty too if you want a reasonable range. Reputable motors like Bafang have all their dimensions on line so you don't end up with a motor too wide for your frame.

Apart from the weight, the 1000w ones aren't bad. They're very smooth and quiet, and they give reasonable torque that's enough for most hills, though efficiency isn't a strong point if you have a hilly ride.

I'm not convinced that there's any difference between the 1000w motors and your one. I think it's just the battery and controller that are different.

Apart from the weight, the 1000w ones aren't bad. They're very smooth and quiet, and they give reasonable torque that's enough for most hills, though efficiency isn't a strong point if you have a hilly ride.

 

I'm not convinced that there's any difference between the 1000w motors and your one. I think it's just the battery and controller that are different.

I'm glad that somebody knowledgeable is sticking up for the poor old DD hub motor. They get a bit of a raw deal on this forum, but I love 'em. One other thing they have going for them is that when you get the ebike bug and eventually end up craving more power, they can be fed many kW and be happy doing so while a geared hub would be sitting in a mess of its own gooey gears and busted freewheel.

Edited February 16, 20179 yr by danielrlee

I don't have an answer to that question but wondered why you needed a 1000w motor...an ungeared one at that... in the first place. I had a 500 watt ungeared (i.e. direct) motor ordered in my ignorance from the US years ago. It has less torque than a later 350w geared bafang. It will be mighty heavy as mine was and your 48volt battery will need to be pretty hefty too if you want a reasonable range. Reputable motors like Bafang have all their dimensions on line so you don't end up with a motor too wide for your frame.

Well, I suppose I didn't really need a 1000w motor but then who really needs an i7 CPU or 16gb of ram lol. I built my bike with top speed in mind, but my setup still has plenty of torque, I can hit over 35mph without pedaling and it carries me up hills like they aren't even there. I actually don't think I would want any more torque, it would be dangerous, the bike would be twitchy and have a tendency to wheelie. It already sets off like a missile hill or no hill, I think you are underestimating these DD motors because I literally don't want for anything, could not be happier. I hardly ever use full throttle for one, I did to get my max speed but it becomes scary after about 30mph anyway. Not to mention DD motors are more efficient at high speed so I can cruise at like 25 and use very little power, your little 250w would be screaming in agony at those speeds, yes they will do it but at the expense of longevity and efficiency. I agree for some folks the 250w motors are the best choice and always will be. I'm already considering building one in fact as a city bike. But for speed, and efficiency at speed, and the ability to overvolt the motor you wouldn't want anything else. I'm running a 14s 52v 16Ah lipo (2x 16Ah 6s + 2x 8Ah 2s in paralell to make a 16ah 2s which is then in series with the 2 6s packs) which should give me about 47 miles range (Without pedaling) and it gets me up to 35mph very quickly. It drops 5 to 10mph up steep hills regardless of what gear I'm in the motor is still doing its thing, which Is a good feeling! Again I see the benefit of smaller motors just for the "stealth factor" alone. However you can't beat a DD for smooth reliable power, I'm just another power hungry hooligan lol.

I'm glad that somebody knowledgeable is sticking up for the poor old DD hub motor. They get a bit of a raw deal on this forum, but I love 'em. One other thing they have going for them is that when you get the ebike bug and eventually end up craving more power, they can be fed many kW and be happy doing so while a geared hub would be sitting in a mess of its own gooey gears and busted freewheel.

That has always worried me too... What if the gears crack in half when your spanking down a hill at 30mph. Would it grind to a holt or would the wheel just stop... If the wheel just locked up that would be catastrophic... That would be a bad day lol. I also love the simplicity of the big DD motors. I come from an RC background and I know for a fact quadcopters with geared motors fail constantly. Adversely the big brushless out runners (our DD motors) are quiet, reliable, efficient enough for most purposes and usually you can add more weight in the form of battery because the motors have more power, so in theory yes more efficient but does it really matter when you can double the battery size? Not to mention the brushless motors are bulletproof compared to a nylon geared high rpm motor. Yes the geared motor has more torque and better efficiency, but who cares when the bigger slightly less efficient motor is quieter, more reliable, has better heat disipation, is smoother, is a lot faster and if it does break its not going to lock up solid and throw you onto the road face first. I think we can all agree road rash is the enemy right? Lol

The gears don't break on geared hub-motors because they're strong enough for what they're supposed to do, so let's not start spreading that myth.

Every motor has advantages and disadvantages. You have to choose one that's best for your type of riding. Generally, the larger geared motors like the Bafang BPM/CST and MAC win at speeds up to 25 mph. The standard 1000w/15000w DD motors win at speeds above that; however, everything depends on winding speed. If the DD motors would be about 230 rpm, they would be a lot more useful, but they're normally 400rpm or more.