Popping and grinding coming from rear wheel

[transposon]

A few months ago I started hearing a popping and grinding sound coming from around my rear wheel. This was only when I put a decent amount of pressure on the pedals. The sounds got louder and louder over time. I originally thought it was the bottom bracket. I took it to a bike shop and they tried replacing the bottom bracket, the derailleur, the freewheel, the big chainring, and the chain. Nothing got rid of the noise. Their guess is that something is wrong with the threading on the hub motor where the freewheel screws onto the motor or that there is something wrong with the axle of the motor.

Here is my setup:

Leaf 1500W rear hub motor with freewheel on a trek mountain bike frame.

Any thoughts on how to troubleshot this? If it is an issue with the threads or axle of the motor, is this something that is fixable, or do I have to get another motor?

Thank you.

 

[Hummina Shadeeba]

Post some video.

 

[E-HP]

I took it to a bike shop and they tried replacing the bottom bracket, the derailleur, the freewheel, and the chain.

I notice a lot of shop operate on trial and error nowadays; sometimes even on purpose.

 

[Diggs]

It sounds like rear axle bearings which is what conventional rear bearings would sound like if they have failed but hub motors usually use pressed-in beefy sealed bearings. What happens when you support the bike and spin the rear wheel by hand. Noises? Any wobbles (play)?

 

[transposon]

I took it to a bike shop and they tried replacing the bottom bracket, the derailleur, the freewheel, and the chain.

I notice a lot of shop operate on trial and error nowadays; sometimes even on purpose.

To be fair, I also requested that they install a larger big chainring and the other parts needed replacing anyway.

 

[amberwolf]

If you pedal pretty hard especially in the higher rear gears (farther from the side of the motor, closer to the frame), the sidecover of the motor can be repeatedly flexed in a way that cracks it around the freewheel mount. I imagine that could make some interesting sounds as it flexes.

If you can unscrew the freewheel and get good clear well-lit (direct sunlight, etc) pics of the sidecover, both straight-on and at varying angles, you might be able to see fatigue cracking in this case. If the cover is painted rather than bare aluminum, it may be harder to see, unless the crack also goes thru the paint, in which case it may be flaking away from the crack and make it more apparent. Sometimes the crack is more apparent from the inside of the cover, but that requires removing the side cover, which is usually harder than just removing the freewheel.


If it is an axle problem, or bearing, you'd have the problem when weight is applied to the wheel, and when that changes during a ride or when riding over bumps, etc., regardless of pedalling or not.

Sometimes taht's also true of the sidecover, but since the loading on it created by pedal torque especially at higher gears is not completely perpendicular to it, it is more likely to make the noise only during pedalling than the other things are.

Some examples of broken covers
https://www.endless-sphere.com/forums/viewtopic.php?f=3&t=6995
https://endless-sphere.com/forums/viewtopic.php?t=104215

A few months ago I started hearing a popping and grinding sound coming from around my rear wheel. This was only when I put a decent amount of pressure on the pedals. The sounds got louder and louder over time. I originally thought it was the bottom bracket. I took it to a bike shop and they tried replacing the bottom bracket, the derailleur, the freewheel, the big chainring, and the chain. Nothing got rid of the noise. Their guess is that something is wrong with the threading on the hub motor where the freewheel screws onto the motor or that there is something wrong with the axle of the motor.

Here is my setup:

Leaf 1500W rear hub motor with freewheel on a trek mountain bike frame.

Any thoughts on how to troubleshot this? If it is an issue with the threads or axle of the motor, is this something that is fixable, or do I have to get another motor?

Thank you.

 

[transposon]

If you pedal pretty hard especially in the higher rear gears (farther from the side of the motor, closer to the frame), the sidecover of the motor can be repeatedly flexed in a way that cracks it around the freewheel mount. I imagine that could make some interesting sounds as it flexes.

If you can unscrew the freewheel and get good clear well-lit (direct sunlight, etc) pics of the sidecover, both straight-on and at varying angles, you might be able to see fatigue cracking in this case. If the cover is painted rather than bare aluminum, it may be harder to see, unless the crack also goes thru the paint, in which case it may be flaking away from the crack and make it more apparent. Sometimes the crack is more apparent from the inside of the cover, but that requires removing the side cover, which is usually harder than just removing the freewheel.


If it is an axle problem, or bearing, you'd have the problem when weight is applied to the wheel, and when that changes during a ride or when riding over bumps, etc., regardless of pedalling or not.

Sometimes taht's also true of the sidecover, but since the loading on it created by pedal torque especially at higher gears is not completely perpendicular to it, it is more likely to make the noise only during pedalling than the other things are.

Some examples of broken covers
https://www.endless-sphere.com/forums/viewtopic.php?f=3&t=6995
https://endless-sphere.com/forums/viewtopic.php?t=104215
Cao6PCf[1].jpg

A few months ago I started hearing a popping and grinding sound coming from around my rear wheel. This was only when I put a decent amount of pressure on the pedals. The sounds got louder and louder over time. I originally thought it was the bottom bracket. I took it to a bike shop and they tried replacing the bottom bracket, the derailleur, the freewheel, the big chainring, and the chain. Nothing got rid of the noise. Their guess is that something is wrong with the threading on the hub motor where the freewheel screws onto the motor or that there is something wrong with the axle of the motor.

Here is my setup:

Leaf 1500W rear hub motor with freewheel on a trek mountain bike frame.

Any thoughts on how to troubleshot this? If it is an issue with the threads or axle of the motor, is this something that is fixable, or do I have to get another motor?

Thank you.

Thanks amberwolf, I took a close look and there is a circular crack in the motor casing around the freewheel. Is this motor not safe to use any more?

 

[Chalo]

I took a close look and there is a circular crack in the motor casing around the freewheel. Is this motor not safe to use any more?

It will probably only continue to damage the part that's already damaged, at least for the near future. Contact Leaf to get a new right side cover. Maybe two, to be safe.

This is one of the major reasons I use front hub motors. My 1500W Leaf is on the front.

 

[transposon]

Thanks Chalo, that makes sense. I've contacted leafbike.

To prevent this in the future, what is the best solution?

Switch to a 16t single speed freewheel, hoping that it can keep the chain closer to the hub motor casing and accept the lower gear ratio?

Keep using the current 13t multi speed freewheel and make sure to use the larger gears when starting from a dead stop? Although I was really hoping to avoid needing to shift.

Or this freewheel with additional bearings? I am not sure I want to get too involved into making custom parts that I have to invest a lot of time into.

 

[Chalo]

If you don't want to shift, use a single freewheel and as large a chainring as you can.

If you want a little more gear range than that, you can use a 3 speed freewheel that isn't much wider than a single speed freewheel. Typically these are 16-19-22T. They won't index cleanly with the shifter you have, though. They're intended to be used with a friction shifter.

 

[transposon]

If you don't want to shift, use a single freewheel and as large a chainring as you can.

If you want a little more gear range than that, you can use a 3 speed freewheel that isn't much wider than a single speed freewheel. Typically these are 16-19-22T. They won't index cleanly with the shifter you have, though. They're intended to be used with a friction shifter.

Thanks, Chalo.


This is my car replacement until I can get my hands on an electric car. I need to be able to do a 32mile round trip for work. Which configuration do you all think is the most reliable - single speed or a multi speed?

 

[Chalo]

If you don't want to shift, use a single freewheel and as large a chainring as you can.

If you want a little more gear range than that, you can use a 3 speed freewheel that isn't much wider than a single speed freewheel. Typically these are 16-19-22T. They won't index cleanly with the shifter you have, though. They're intended to be used with a friction shifter.

This is my car replacement until I can get my hands on an electric car. I need to be able to do a 32mile round trip for work. Which configuration do you all think is the most reliable - single speed or a multi speed?

Reliable? Single speed for sure. Having more gear range is so you can pedal more, or so you can pedal both with and without motor power.

If you have a single speed rear freewheel, you can still have 3 speeds in front. 52-42-30 is a normal road triple, 48-38-28 is a "trekking" triple (that used to be ordinary MTB stuff). 42-32-22 MTB triple isn't useful for what you're doing.

I can imagine getting by with 3 ratios: one for making good time, one for tooling around, and one for limping home or climbing hills.

 

[transposon]

After the casing on my 1500W leaf motor cracked around the freewheel, I ordered a couple of replacement covers. Unfortunately the bearings on one of them does not turn smoothly and sometimes will make a slight grinding sound when turned. Is this something that I should be worried about?

Leaf claims that it is fine and that the bearings were inspected before shipment, but I am skeptical.

 

[transposon]

Thanks Chalo, those are sensible suggestions. I ordered two replacement motor covers and one has bearings that grind slightly and do not turn smoothly. Leaf doesn't think it is a problem.

 

[amberwolf]

At a guess, they pushed (or hammered) the bearing in by it's inner race instead of it's outer race, which puts pressure on the races and balls and can damage them, and can cause what you're seeing.

Unfortunately some sellers don't think *anything* is a problem, even if you show them the unopened undamaged package that's on fire still on the shipping truck.

 

[amberwolf]

At a guess, they pushed (or hammered) the bearing in by it's inner race instead of it's outer race, which puts pressure on the races and balls and can damage them, and can cause what you're seeing.

Unfortunately some sellers don't think *anything* is a problem, even if you show them the unopened undamaged package that's on fire still on the shipping truck.

 

[Chalo]

You can take the motor covers to an electric motor service shop and have them replaced.

 

[Bullfrog]

Best single speed freewheel is the White Industries "Green" Trials Freewheel. 72 points of engagement.

White also produces a two speed freewheel and their regular freewheel is better than most.