NuVinci Hub
- Thread starter kennyb
- Start date
espokestech
New Member
If you are experiencing a "thrumming" with your gates drive, then it is likely that your belt is too tight. Max tension is 50 psi, and should be adjusted with a Gates "clicker" tool. Many bike shops and owners unfamiliar with Gates belts tend to overtighten them, treating them like a fan belt on a car. My advice is to loosen the dropout bolts and look in the back of the dropout for a 3mm hex bolt. Turning them clockwise loosens the belt, counterclockwise tightens. Turn them in a turn or two, and wiggle your wheel back and forth to make sure it moves forward. Torque the dropout bolts and give it a go. If your belt slips a tooth or two, you're too loose. If it thrums, too tight.
Too tight can damage the bearings on most hubs, and damage the shift mechanism on your NuVinci. The only NuVinci hubs I have seen with damage are from this issue.
Good Luck!
Dan at eSpokes
Too tight can damage the bearings on most hubs, and damage the shift mechanism on your NuVinci. The only NuVinci hubs I have seen with damage are from this issue.
Good Luck!
Dan at eSpokes
Thanks! Makes sense. I'm travelling out of country and will try this and report back when I get back in October.
Unfortunately, no. Tension has been confirmed as being correct. Lowering tension slightly (still within correct range) had no effect on thrumming. Pedalling with the motor off (for exercise) still exhibits thrumming. I've only approximately 200miles on the bike (as I've been travelling a bit) and have yet to convince myself that the problem will disappear with break-in time. Oh, well...
My local bike shop was in contact with R-M Germany. According to R-M there are known problems with some dropout systems (the little metal things that hold your wheel and are connected to the frame - http://www.slowtwitch.com/Tech/Dropout_and_Hanger_101_3354.html).
My shop has ordered the 2 new parts. Fingers crossed that will solve the annoying vibration...
My shop has ordered the 2 new parts. Fingers crossed that will solve the annoying vibration...
It's harmonics. The belt is of a given length, tensioned between two points, like a string on a violin. The two points vary slightly when the cogs rotate, so the fundamental frequency varies, and produces a 'strumming' effect. It would be interesting to mount a wheel halfway on the tensioned portion of the belt. It would not have to provide any force; it would be like a violinist's finger resting on a vibrating string, but it would serve to halve the sound's frequency, and may move the "noise" into a less objectionable realm in the frequency spectrum.
Simplistically that makes sense, but I think it is not the answer. First, many people have told me that as the belt breaks in the vibration will diminish (without requiring a change in tension). Second, I had the tension of the belt only bike reduced (still within recommended range) with no change in the "thrumming" sensation. I hope I'm not wrong, as the vibration is annoying. My experience with this bike has turned me off to the belted Tinker.
Got my bike back today and the vibration problem seems to be solved. I had a vibration free trip this afternoon. My LBS installed a new drop-out system and re-aligned the rear wheel. Apparently the rear wheel allignement needs to be spot on. In some cases a bad drop-out can make perfect allignement imposible. According to my LBS (and R&M) that caused the problem...
In the case the vibration should return the bike will be sent back to R&M. Hope that won’t be necesarry. Keep you posted.
In the case the vibration should return the bike will be sent back to R&M. Hope that won’t be necesarry. Keep you posted.
Unfortunately the vibration came back after a few days... My LBS got back in touch with R&M en they will now replace the sprockets. They believe the vibration comes from the sprockets that are probably to small. They will replace them with larger ones...
PS: I'm no longer the only one with this problem at my LBS. So this problem could very well be more general.
PS: I'm no longer the only one with this problem at my LBS. So this problem could very well be more general.
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In the meanwhile for the techies among us:
http://ww2.gates.com/IF/facts/documents/Gf000379.pdf (see 2.4: chordal action)
en http://chain-guide.com/basics/2-2-1-chordal-action.html
http://ww2.gates.com/IF/facts/documents/Gf000379.pdf (see 2.4: chordal action)
en http://chain-guide.com/basics/2-2-1-chordal-action.html
Alasdair Macfarlane
New Member
That article about roller chain drives and it's discussion about "chordal action" is very interesting and seems to support my theory that the "thrumming" is a function of a small chainwheel rotating at 2.5 times the crank rotation. My Delight has now clocked up 5500 km and I have got used to and accepted the thrumming on this bike. It is a fantastic bike in every respect except for this small annoyance. I will say that I have recently replaced the chain because it was showing 7% stretch but I would think that is reasonable for a mid drive motor and I have been riding in hilly terrain and towing a BOB trailer.
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To be really really sure, in a desperate attempt, the bike has been tested with a different rear wheel and was driven with a different Bosch motor. Vibrating was still there.
The bike is now sent back to Germany. Vibrating is most probably caused by a bad frame (because all other components can be ruled out by now)...
The bike is now sent back to Germany. Vibrating is most probably caused by a bad frame (because all other components can be ruled out by now)...
Robert W Green
Member
I've heard that about the Nuvinci but don't recall ever hearing why. If I ride conservatively and don't purposely tax the drive won't it be ok, or will just know that it's hooked up to a 750w mid drive and fry itself? Why don't they make one that is rated for an American ebike instead of trying to make us conform with restrictive European laws.
Hi, did you ever get to the bottom of the problem ? I have a Reese and Muller with the same problem.
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