Motor issues - CX Performance

[andrewmorgan90]

Hi guys, looking for some advice. Went out for a ride yesterday, nothing too crazy just normal off-road stuff. On the cycle track back home noticed there’s a clicking noise coming from my motor but only when freewheeling? Or riding above the cut off point. Anyone had similar experiences?

 

[Doomanic]

When you are freewheeling the motor shouldn't be turning, if it is there's a problem.

@Bearing Man any ideas?

 

[Bearing Man]

Hi guys, looking for some advice. Went out for a ride yesterday, nothing too crazy just normal off-road stuff. On the cycle track back home noticed there’s a clicking noise coming from my motor but only when freewheeling? Or riding above the cut off point. Anyone had similar experiences?

I have to agree with Doomanic. From your explanation, the motor is clicking when freewheeling and by default, not turning. And it's also clicking whilst riding above cut-off and therefore, turning!
But not clicking when riding normally? This may sound a bit of an odd question, but, do you have Crank Brothers wheels by any chance? When the spokes become loose, they can click when not under load.
Failing that, I can't think of anything inside the Bosch motor that would click while no rotating?

 

[andrewmorgan90]

I have to agree with Doomanic. From your explanation, the motor is clicking when freewheeling and by default, not turning. And it's also clicking whilst riding above cut-off and therefore, turning!
But not clicking when riding normally? This may sound a bit of an odd question, but, do you have Crank Brothers wheels by any chance? When the spokes become loose, they can click when not under load.
Failing that, I can't think of anything inside the Bosch motor that would click while no rotating?

Thanks for your response. Yes, it’s a bizarre one. Turned the bike upside down tonight and can not replicate the noise so I’m thinking there may be something that’s worked itself loose. I’ll do more investigating and keep you posted!

 

[Bearing Man]

Thanks for your response. Yes, it’s a bizarre one. Turned the bike upside down tonight and can not replicate the noise so I’m thinking there may be something that’s worked itself loose. I’ll do more investigating and keep you posted!

Ahh, in that case, there is a circlip behind the metal crankshaft gear that can snap and then the bits are floating around in the motor. This is normally accompanied by a metallic whining sound when the motor is under load and wouldn't explain the clicking noise while free wheeling?
Does it do it if you get off the bike, lift the back wheel and pedal the motor round? Also the most common cause of "clicking" is loose motor bolts. Give them a nip up and see what happens.

 

[SquireRides]

My previous, broken, CX motor had one symptom when freewheeling: The chain and chaining would turn!

Crazy I know, but it must be something to do with the motor disengaging. The problem was my drive side bearing had gone. The main symptom was the motor being very noisy when turning the cranks. But I also had situation where the cranks seized (couldn't roll the bike *backwards*) and also where the chain/chaining would move when freewheeling or pushing the bike.

So, yeah, it *is* possible that a motor problem could be evident even when freewheeling, if you're seeing similar symptoms to me.

 

[Bearing Man]

My previous, broken, CX motor had one symptom when freewheeling: The chain and chaining would turn!

Crazy I know, but it must be something to do with the motor disengaging. The problem was my drive side bearing had gone. The main symptom was the motor being very noisy when turning the cranks. But I also had situation where the cranks seized (couldn't roll the bike *backwards*) and also where the chain/chaining would move when freewheeling or pushing the bike.

So, yeah, it *is* possible that a motor problem could be evident even when freewheeling, if you're seeing similar symptoms to me.

This is odd!? I don't dispute that it happened, stranger things and all that. I just can't quite work out how this happens? When you stop peddling i.e. freewheel, the rear cassette should take over and stop the chain moving? The motor crankshaft can't move because your standing on the pedals. The drive sprocket had a freewheel mechanism (one way clutch) inside the motor, so is it possible that the rear cassette freewheel has become stiff and is "pushing" the chain round? As you state, this happened even when you pushed the bike without the motor engaged. This is intriguing and I would love to get to the bottom of it.

 

[SquireRides]

This is odd!? I don't dispute that it happened, stranger things and all that. I just can't quite work out how this happens? When you stop peddling i.e. freewheel, the rear cassette should take over and stop the chain moving? The motor crankshaft can't move because your standing on the pedals. The drive sprocket had a freewheel mechanism (one way clutch) inside the motor, so is it possible that the rear cassette freewheel has become stiff and is "pushing" the chain round? As you state, this happened even when you pushed the bike without the motor engaged. This is intriguing and I would love to get to the bottom of it.

I know right! First time it happened (and it happened a lot before i had the motor replaced) I was staring at it like WTF??

When it happened I could tap the chainring with my foot and that was sometimes enough to then engage the rear hub freewheel instead, so the chain/chainring stopped moving.

The crank shaft seems to be able to move independent of the pedal, which makes sense thanks to that 2x multiplier the CX puts out (1 crank turn = 2 chainring turns, or something like that) - They can't be physically directly coupled.

Maybe something other than the bearings seized? Or... I dunno. Something in the motor was deciding to freewheel itself, and must've needed less force to engage than the rear hub freewheel. I had thought it was a freehub problem, and indeed it did feel a bit 'sticky' when i tried to service it (never did, didnt have the massive hex key you need).

Anyway, hasn't happened once since the new motor...

 

[Doomanic]

My first motor did the same thing, it was the first indication to me that failure was imminent.

 

[andrewmorgan90]

Thanks for all your advice, it’s much appreciated. Just to keep you updated. Gave everything a tighten as suggested, and took it for a quick ride that includes a big hill. For the most part there’s no clicking when freewheeling anymore however when I put any real pressure through the cranks then the click returns. Starting to think it maybe the crank arms/ pedals. But bike mechanic I ain’t, it’s all new to me!

I’m going to invest in a bike workstand tomorrow to take a proper look at it. It’s driving me mad ?

 

[SquireRides]

Top 3 things i spend my time doing as a mountain biker:
1. Looking at things on the internet to buy.
2. Riding.
3. Trying to work out where that noise is coming from....

 

[Wiltshire Warrior]

Hi Andrew - have you figured it out yet?

 

[andrewmorgan90]

I think it has to be the cranks. I can’t reproduce the sound when it’s in the stand but when there’s weight/ power going through the cranks there’s a creak/clicking sound.

 

[Bearing Man]

Bit of grease on the crank should sort that. But, if it doesn't? Look at your front sprocket. If it is dry, or a cheap, stamped out sprocket, lube it or change it.

 

[Couchy]

We had this on a mates Bosch bike, when he put a lot of pressure through the pedals it clicked or creaked. In this case it was the motor mounting bolts that needed a tighten up simple as that

 

[pamartia]

My motor (Bosch Gen4 Trek Rail )started making noises when coasting. I removed my feet from the cranks and the cranks were moving forward. Any ideas?

 

[Mteam]

My motor (Bosch Gen4 Trek Rail )started making noises when coasting. I removed my feet from the cranks and the cranks were moving forward. Any ideas?

Sounds like your freewheel hub on the back wheel is not actually freewheeling like it should when you coast.

Take the hub apart and clean it all up and look for issues with the ratchet mechanism

 

[Bearing Man]

My motor (Bosch Gen4 Trek Rail )started making noises when coasting. I removed my feet from the cranks and the cranks were moving forward. Any ideas?

When the cranks were moving was the motor still driving the bike forward?

 

[pamartia]

When the cranks were moving was the motor still driving the bike forward?

I solved the issue, it was the rear hub that was engaging and moving the cranks forward when freewheeling