Noisy drivetrain

[Jan]

My S40 makes a loud creaking noise whenever I exert force on the pedals. I can't locate exactly where the sound comes from, because it travels up and down the boom. Has anyone else experienced this before? Any suggestions on how to diagnose and fix the problem?

 

[chicorider]

Hi Jan. I had a similar noise on my old V20, which had a similar design to your S40. In my case, the culprit was the clamp bolt that connects the boom to the steering column. Others have commented on this particular spot too, over the years. Some have solved it by checking/correcting the torque they've put on the bolt. Others have pulled the bolt out, cleaned it, and lightly lubricated the threads and the outer sleeve. I solved my creak by sliding very thin mylar washers between the inside of the boom clamp and the steerer tube top cap, where the bolt slides through. Most of the bolts on these bikes only need about 5nm of torque, but the boom clamp bolt needs more. The spec for my V20C is 10nm for that bolt. I would imagine that the S40 would be about the same.

Another area to check are the two clamps that connect the bottom bracket end of the boom to the chainstays. Those should be about 5nm all around, with even gaps at all four bolts.

I hope this helps.

 

[Jan]

Thanks for the quick response! I don't think that the noise comes from the steering column. The picture below shows the parts that can hold with my left hand whilst cycling. If the sound came from those connections, my hand would muffle it. It doesn't, so the sound must be coming from lower down. I initially thought that it came from the connection of the derailleur to the fork, which was only held by a very short M4 screw. I replaced this with a longer M4 screw. This new screw did tighten the connection but the noise actually worsened because of it.

 

[RAR2]

Thanks for the quick response! I don't think that the noise comes from the steering column. The picture below shows the parts that can hold with my left hand whilst cycling. If the sound came from those connections, my hand would muffle it. It doesn't, so the sound must be coming from lower down. I initially thought that it came from the connection of the derailleur to the fork, which was only held by a very short M4 screw. I replaced this with a longer M4 screw. This new screw did tighten the connection but the noise actually worsened because of it.
View attachment 19253

Jan,
The fastest easiest thing to do is pull that boom to steering tube bolt and grease it then put it back at the proper torque. Everything else takes longer and is more complicated.

I went through the same process and found that bolt was the problem.

 

[Boreen bimbler]

I used a little carbon paste (the stuff that helps seatposts ect grip) in all my S40 boom joints when I had creaks at the beginning. My theory was as it's designed for parts with lower torque settings it should do the job with no need to over tighten. Been fine for about 3 years now.

 

[Graham Mccollum]

Another thing to check out your wheel. I also had this issue and it was usually the headset clamp as described... But then recently a new creak sounded. I found my wheel rim had crack around some of the nipples so when the wheel torqued the rim was creaking! Wheel has now been condemned and replaced.