Hub Motor Drag

[Deleted member 4366]

I was cycling home from work today on my new Giant BPM conversion, which had only covered about 20 miles from new, when I noticed noise from the motor when I was free-wheeling. I had the motor on minimal assist all the way home so it was no problem, but sure enough the clutch was stuck so that the motor turned when the wheel was turned in both directions.

I was going to disassemble it to free- it off, and then I had an idea. I turned the bike upside-down and hit the tyre with a big hammer in the forward direction. On about the third hit, the clutch freed itself.

maybe some of the people that have experienced drag with hub-motors got this same problem, which is probably quite common, so here's a simple solution.

 

[John L]

I was cycling home from work today on my new Giant BPM conversion, which had only covered about 20 miles from new, when I noticed noise from the motor when I was free-wheeling. I had the motor on minimal assist all the way home so it was no problem, but sure enough the clutch was stuck so that the motor turned when the wheel was turned in both directions.

I was going to disassemble it to free- it off, and then I had an idea. I turned the bike upside-down and hit the tyre with a big hammer in the forward direction. On about the third hit, the clutch freed itself.

maybe some of the people that have experienced drag with hub-motors got this same problem, which is probably quite common, so here's a simple solution.

How did you think to do that I have visions of you taking a sledge hammer and sorting out the clutch but crushing the wheel!

Seriously though thats worth knowing - cheers

John

 

[mechaniker]

maybe some of the people that have experienced drag with hub-motors got this same problem.

the BPM Motor clutch is a problem, some is failproduction and the trouble will come back, most time the only help is a new one

regards
frank

 

[Oxygen Bicycles]

I woudn't think about hitting it with a hammer but well done to a simple and quick solution.

all the best

Andrew

 

[indalo]

I turned the bike upside-down and hit the tyre with a big hammer in the forward direction. On about the third hit, the clutch freed itself.

Gosh, that seems a bit extreme! Were you a plumber in a previous existence?

Indalo

 

[mechaniker]

here is a photo of the inside clutch from a BPM-Motor. the problem is that the channel for the roller is to flat and the roller lock himself.

 

[Deleted member 4366]

Just to make it clear what I did: I hit the tyre in a tangential direction with a 2lb hammer. I didn't hit the rim or any part of the wheel.

Frank, nice to see you posting again, you've been quiet for quite a long time. Thanks for that useful information. Are all clutches the same or was it just a bad batch? If I need to replace the clutch, where do I get a good one from and how can I know that it's good? I'll keep you all informed whether it comes back again.

 

[flecc]

Smart move with that hammer blow d8veh. A few years ago I saw a VW mechanic do the same on a van when the drum brake had locked on solid. He used a club hammer and gave the steel wheel a brutal looking knock which instantly freed it.

 

[mechaniker]

Frank, nice to see you posting again, you've been quiet for quite a long time. Thanks for that useful information. Are all clutches the same or was it just a bad batch? If I need to replace the clutch, where do I get a good one from and how can I know that it's good? I'll keep you all informed whether it comes back again.

hi
the reason for that i´m so quiet, is i give up my business, i only make a sell out with the rest what i have in basement. I gave my business to my friend in China ebike accessory - BY Ebike Accessory Co., Ltd. (if it is to much comercial for somebody that i send this websiteaddress, sorry for that, i will not do again)

But sometime it is hard to stay away;-) so sometime i have a look around and if i see some intresting thread i answer.

Your problem with the clutch,
Bafang have in some charge problem with the BPM clutch, i have two original here as a sparepart complete with sprocket for in case.

BTW, i saw your thread about swxk as chaindrive, i still have a clutch for swxk with lock in other direction, in case you want monuting your sprocket to the right side. check this photo


regards
frank

 

[mechaniker]

A few years ago I saw a VW mechanic do the same on a van when the drum brake had locked on solid. He used a club hammer and gave the steel wheel a brutal looking knock which instantly freed it.

As a car mechanic, i say good way of repair
a good mechanic need a hammer and a pipe wrench ;-) more is luxury

have agood day
frank

 

[Deleted member 4366]

hi
the reason for that i´m so quiet, is i give up my business, i only make a sell out with the rest what i have in basement. I gave my business to my friend in China ebike accessory - BY Ebike Accessory Co., Ltd. (if it is to much comercial for somebody that i send this websiteaddress, sorry for that, i will not do again)

But sometime it is hard to stay away;-) so sometime i have a look around and if i see some intresting thread i answer.

I'm sorry to hear that you've given up your business. I saw that the things on your website were going down, which puzzled me.

I have one more question regarding crank drive, because I'm just starting a new project with a Cute motor. On my last one, the chain was jumping on the motor sprocket, which is a BMX single speed free-wheel 18 teeth. I added a chain tensioner to get more chain on the sprocket, but still it jumps sometimes. I will make the tensioner more rigid, which might solve it. I see the one on your website has a tensioner also, but none of the other German ones have a tensioner and they have smaller motor sprockets. Do you know if they have any problems with the chain jumping under high load? I want to know whether the problem I have is because the motor holding plates are not rigid enough, or if it's a problem of the sprocket or anything else.

 

[mechaniker]

Do you know if they have any problems with the chain jumping under high load? I want to know whether the problem I have is because the motor holding plates are not rigid enough, or if it's a problem of the sprocket or anything else.

i never hear about jumping chains and i would be surpriced if the chain is jumping because i have driven many crankdrive´s.
The only one motor with problem in this way was my cyclone. The cyclone mounting-plate always was moving under higher load, so using was under hard conditions
But i have driven this cyclone at my cargobike with higher voltage and higher amps, after i see the problem i have weldingt a plate for the motor to the frame and then all was fine ;-)
have a look at this photo, i have designed and build the bike by myself complete in stainless steel with chaindrive and the front you can slanting in a angle to the rear so that the driving was more like bikeriding

Another company make a chaindrive with swxk (Motor come from me) and also never had problems with chain-jumps

regards
frank

 

[johnc461165]

As a retired engineer a hammer used correctly can be equal to anything done by a surgeon

 

[oigoi]

I'm sorry to hear that you've given up your business. I saw that the things on your website were going down, which puzzled me.

I have one more question regarding crank drive, because I'm just starting a new project with a Cute motor. On my last one, the chain was jumping on the motor sprocket, which is a BMX single speed free-wheel 18 teeth. I added a chain tensioner to get more chain on the sprocket, but still it jumps sometimes. I will make the tensioner more rigid, which might solve it. I see the one on your website has a tensioner also, but none of the other German ones have a tensioner and they have smaller motor sprockets. Do you know if they have any problems with the chain jumping under high load? I want to know whether the problem I have is because the motor holding plates are not rigid enough, or if it's a problem of the sprocket or anything else.

Dv8eh this sounds to me like a mismatch between the chain pitch and the sprocket teeth, possibly because of wear on either component. Might be worth trying a different chain.

It might also be the chain stretching under load so perhaps a stronger chain.

 

[vhfman]

I was thinking along the same lines as you oigoi re: the chain. d8veh I see you are using a BMX freewheel which are often designed for 1/8” chain and more than likely you are using a 3/32” chain and chain wheel, worth checking the compatibility of the chain and freewheel sprocket. Some BMX sprockets are OK with 3/32” chains.

Chris

 

[Deleted member 4366]

I was thinking along the same lines as you oigoi re: the chain. d8veh I see you are using a BMX freewheel which are often designed for 1/8” chain and more than likely you are using a 3/32” chain and chain wheel, worth checking the compatibility of the chain and free-wheel sprocket. Some BMX sprockets are OK with 3/32” chains.

Chris

I was thinking along the same lines, but the chain is a brand new BMX one from Halfords and there's no visible wear on the sprocket. They never talk about pitches and widths, only in speeds : single speed, 6 speed, 9speed, etc, which doesn't make sense to me. He said it was a single speed BMX chain, although it was their cheapest and seems to be stretching really fast. I tried a normal bike chain before but it didn't match the motor sprocket. I asked the guy at Halfords whether the sprockets were different widths or pitches and he only replied in speeds! Could someone give me a translation between speeds and dimensions? The German crank drive conversions seem to use a single sprocket out of a gear cassette and I guess a normal chain. Maybe that's better for some reason.

 

[flecc]

I was thinking along the same lines, but the chain is a brand new BMX one from Halfords and there's no visible wear on the sprocket. They never talk about pitches and widths, only in speeds : single speed, 6 speed, 9speed, etc, which doesn't make sense to me. He said it was a single speed BMX chain, although it was their cheapest and seems to be stretching really fast. I tried a normal bike chain before but it didn't match the motor sprocket. I asked the guy at Halfords whether the sprockets were different widths or pitches and he only replied in speeds! Could someone give me a translation between speeds and dimensions? The German crank drive conversions seem to use a single sprocket out of a gear cassette and I guess a normal chain. Maybe that's better for some reason.

Apart from some goods bike chains which have a 5/32" internal roller width, all bike chains are 1/8" or 3/32" internal roller width. 1/8" is for single speed or hub gear bikes, 3/32" for all derailleur chains.

The derailleur chain speed differences are in the external maximum width. All chains up to 8 speed usually have an external width of 7.1 or 7.2 mm. 9 speed chains have an external width of 6.8 mm, and 10 speed chains are 6.2 mm external width. So it comes down to a matter of the the side plate thicknesses and rivet end protusions. Hope this helps.

 

[Deleted member 4366]

Thanks Flecc. Nice and clear.

 

[Mussels]

Thanks Flecc. Nice and clear.

Halfords likes to be vague like that, they do sell some right rubbish so whenever I see them refuse to give basic technical info I just walk out and buy it somewhere sensible.

 

[oigoi]

Might an industrial 1/2" pitch chain provide a stronger solution? Not sure if it would mesh with the sprocket teeth correctly but if it did it would be a lot stronger. You could pop into a local supplier (I use thelocal branch of Eriks) and try it for fit to avoid expense of buying it if it doesn't fit. This kind of thing:

Buy Chains, Links & Accessories British std chain,080-1 12.7mm pitch Witra CW081-1 online from RS for next day delivery.