It's got a Gates belt drive. I assumed,perhaps rashly, that such new fangled gubbins didn't need a guard.
First ride on a Foffa NuVinci Black
- Thread starter annirak
- Start date
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Pale Rider
Legendary Member
The bike has two interesting technologies, but the weakness of both - according to some - is a little extra drag.
NuVinci talk a lot about ebikes on their website, I suspect because the extra drag of the hub is one of the reasons it hasn't caught on on push bikes.
i've ridden a couple of NuVinci ebikes, one with the clever auto shifting.
Both rides were not long enough to work out if I liked the constantly variable transmission or not, but I did detect a tiny bit of extra drag.
One of those ebikes also had a belt drive.
The design of the belt is a compromise, the teeth need to be deep enough to grip the sprockets, but make them too deep and there is stiction as the belt un-meshes, which it is doing all the time at the bottom of the front ring and at the top of the rear sprocket.
Gates, who make the belt, will tell you there's no extra friction over a chain, but some cyclists will tell you otherwise.
I suspect the combination of belt and hub on the OP's bike means it does have a tiny bit more drag than an identicial bike with chain and derailers would have.
http://nuvincicycling.com/en/products/harmony.html
NuVinci talk a lot about ebikes on their website, I suspect because the extra drag of the hub is one of the reasons it hasn't caught on on push bikes.
i've ridden a couple of NuVinci ebikes, one with the clever auto shifting.
Both rides were not long enough to work out if I liked the constantly variable transmission or not, but I did detect a tiny bit of extra drag.
One of those ebikes also had a belt drive.
The design of the belt is a compromise, the teeth need to be deep enough to grip the sprockets, but make them too deep and there is stiction as the belt un-meshes, which it is doing all the time at the bottom of the front ring and at the top of the rear sprocket.
Gates, who make the belt, will tell you there's no extra friction over a chain, but some cyclists will tell you otherwise.
I suspect the combination of belt and hub on the OP's bike means it does have a tiny bit more drag than an identicial bike with chain and derailers would have.
http://nuvincicycling.com/en/products/harmony.html
OP
OP
annirak
Veteran
- Location
- Cambridge, UK
I was well aware of this on both counts before I purchased. The interesting thing about the marketing of both products was the way they dismiss the drag:
- NuVinci says that you make up for the extra drag by being able to go between gears.
- Gates says that a brand new clean chain is lower drag, yes, but who has a brand new, clean chain?
I was looking at replacing chains every 3 months since I do about 16 miles/day in all weathers with 50kg of trailer and child. Cogs, probably every 9 months. Because of that commute, I was looking for:
- Steel frame
- Belt drive
- Disc brakes
GrumpyGregry
Here for rides.
It's a clever spec for the target use at a keen price I guess the built to order bit speaks volumes about the target market and how conservative we are as British cyclists.
GrumpyGregry
Here for rides.
What spec would a dynohub need to have to meet your needs though?
mjr
Comfy armchair to one person & a plank to the next
- Location
- mostly Norfolk, sometimes Somerset
As long as you've a low enough gear, I think you get the energy back on the descent. The only bit you don't is the added friction drag which is proportional to weight.
mjr
Comfy armchair to one person & a plank to the next
- Location
- mostly Norfolk, sometimes Somerset
Wind resistance is there no matter how you get to that speed, but braking is a fair point.
OP
OP
annirak
Veteran
- Location
- Cambridge, UK
I should have taken pictures yesterday... No racks yet!
OP
OP
annirak
Veteran
- Location
- Cambridge, UK
Probably about 20W. That's sufficiently high that I don't think I'd want to ride with it.
The supplementary question then is "what are you hoping to power from the dynamo?"
GrumpyGregry
Here for rides.
That's quite a lot of watts, what?
- Location
- Inside my skull
Maybe he is going to mount a slow burn toaster?
swansonj
Guru
...and just to spell it out, the reason @User is right is that wind resistance is non-linear with speed.
If wind resistance were proportional to speed (linear) you would indeed gain as much from reduced wind resistance at lower speeds up hills as you lost fromhigher speed downhill.
But wind resistance is proportional to the square of speed (and power dissipated against the wind therefore proportional to the cube of speed). So you loose a lot more pushing the wind at the higher speed downhill than you save uphill.
OP
OP
annirak
Veteran
- Location
- Cambridge, UK
It's a 5m long light strip attached to the trailer. It's got 300 LEDs on it! I use it to outline the trailer which makes it quite visible on the dark nights!
OP
OP
annirak
Veteran
- Location
- Cambridge, UK
@annirak Let's have some pictures!
Photos!
The little hill as a "gear" indicator is clever.
The "chain guard" doesn't quite cover the front of the belt. I'm considering trying to adjust it.
Drive side...
Mounting the front mudguard was interesting, due to the disc brake. SKS suggests using spacers (shipped with the mudguards) to space the front mounts out from the disc brake. I needed a 30mm bolt, but the SKS Longboards only came with a 25mm bolt, so I had to hit up the LBS for another one. They only had a 35mm bolt, so I ended up using a few more spacers, but I'm reasonably happy with the result.
The trailer hitch mounts to a special axle nut. It took some research, but one of the Thule adaptor nuts for SRAM hubs matches the Nuvinci hub. I'm glad I have a torque wrench. The fixing torque for this nut is so high that I wouldn't have believed that it was on that tight.
Non-drive side
