Gates belt drive and vibrations

little_harry

New Member
I have a bike with a Gates belt drive, Rolhoff and a Bosch CX Performance (gen2) engine.

I do experience a lot of vibrations from the belt. I have the mechanics at the shop to look at it, and they say "it's normal". They also checked the tension on the belt.

My question is simple: How much vibrations is normal for a belt drive setup?
 

Alaskan

Well-Known Member
I have the gates belt with Rohloff and Bosch high speed motor - no vibrations. What you are experiencing is definitely not normal. Ask the shop if they have the gates krikit tension checker tool or if they use the phone app to check the tension level. These are the two best ways to check for proper tension.. Here is a video demo
I suspect your tension is too low. The phone app is free but some find it hard to use (it is spot on for me) for starters you could download the app and see if it gives you consistent readings. https://play.google.com/store/apps/details?id=com.gates.carbondrivecalculator
 

Over50

Well-Known Member
I have a bike with a Gates belt drive, Rolhoff and a Bosch CX Performance (gen2) engine.

I do experience a lot of vibrations from the belt. I have the mechanics at the shop to look at it, and they say "it's normal". They also checked the tension on the belt.

My question is simple: How much vibrations is normal for a belt drive setup?

I could have sworn something was discussed in an older thread and it wasn't caused by improper tension but by another component. Something about a strumming sound at higher speeds. But alas I couldn't find anything when searching the threads. There are comments on some regular bike forums but that is perhaps apples to oranges. But anyway, has your shop checked other components that might lead to a small misalignmen? Is this something that has always occurred on your bike or something that just recently cropped up? Age on the belt?

I found this at bike forums . net so maybe it supports the case that there could be another component involved that needs to be checked/trued etc:

1580576313163.png
 
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little_harry

New Member
I could have sworn something was discussed in an older thread and it wasn't caused by improper tension but by another component. Something about a strumming sound at higher speeds. But alas I couldn't find anything when searching the threads. There are comments on some regular bike forums but that is perhaps apples to oranges. But anyway, has your shop checked other components that might lead to a small misalignmen? Is this something that has always occurred on your bike or something that just recently cropped up? Age on the belt?

The bike is only 3 months old. So everything is quite new.

I have checked the tension on the belt with the app and it looks OK. May a little tight. I measured 60 Hz and that's recommended for "single speed", but for internally geared hub its recommended 35-50 Hz. But the recommendation is just a starting point. But now I know the tension it's not to low.

I think it's more sound/vibrations when I pedal really hard.

Maybe misalignment could be the answer?
 

indianajo

Well-Known Member
Maybe misalignment could be the answer?
When belts did this in the factory, either the belt was warped, or the flange of one of the pulleys was dented in or it was mounted crooked or the shaft was bent. If the frequency of the vibration is same as one of the pulley diameters, spot on. If the frequency is the belt rotation frequency, that's it. But you don't have a variable freq strobe to spot the problem as we did. You put a chalk mark on the pulleys and the belt and make them stand still with the strobe to see the frequency of that component. If the belt is wiggling with the chalk mark standing still on one of the pulleys, the cause is not that one. If it is neither pulley, it is probably the belt.
Of course very difficult to get constant speed rotation on a bicycle. Electric motors do that all day.
 

SwiftySanders

Member
Region
USA
City
New York, NY
I have this same issue. 🤔🥺🤦🏾‍♂️

To me it feels like the belt pn my bike. It seems like it happens in rotation or something. Feels like something is caught up in the belt. Im gonna ask them to check for belt or cog issues.