In an article a month or so back we looked at the NuVinci N360 as a fat-bike friendly hub with a standard chain drive and the promise of a belt drive setup using the Gates CenterTrack system to come. Well, here it is!
To install a belt drive system on your bike you will either need a frame like the Northpaw we used that was built specifically to accommodate a belt drive system and uses a Paragon sliding drop to tension the belt along with a belt break at the drop on the seat stay or you can have a belt split welded in to the seatstay by a frame builder. Either way, that is how you get a belt with no way to break it onto the drive cogs. Note that you will need someway to tension the belt so suitable frames will have a horizontal or track drop or an eccentric BB to tension the belt.
Since this bike was already built up using the Nuvinci and a chain previously the conversion to the belt was pretty straight forward.
First order of business was to swap out the older freehub body on the NuVinci for the new, belt compatible version. This is fairly easy if you are mechanically inclined and have some experience with small parts, snap rings and such. If not, your local bike shop can do this for you. If you got your Nuvinci in the last couple of months this may not be necessary because the modified freehub is a running change to the N360. A call to Fallbrook can help you identify your freehub. (888-NuVinci).
A great resource for those of you who want to work on your NuVinci is:
and, while there are no belt specific tips, the rest of the info is very valuable and includes a section on changing the freehub, needle bearings etc.
Next we needed to get the 24T, NuVinci-specific Gates Cog installed. The cog needs to go on with the lettering facing out. To put it another way it needs to be installed so the teeth are closer to the hub rather than further away. A snap ring holds this on. It can be a bit of a bear to get that snap ring seated, make sure to start with the end at one of the recesses, but as long as the diameter of the snap ring when installed is 39mm or less you are gravy.
Then, follow the NuVinci instructions to install the shifter interface, non-turn washers, etc. and get the wheel ready to bolt on to the frame.
The standard belt line on the NuVinci N360 using the Gates rear cog is 47.5mm so adding in the 17.5mm offset that a fatbike uses that makes for a 65mm belt line at the front cog. This should be no problem to achieve on most fatbikes. I mounted the Gates 39T front cog to an e*13 100mm fatbike crank on the inside of the 104mm BCD arms and am spot on at 65mm. Nice! In some other installations it may be necessary to fiddle here a bit. The belt line of the Centertrack system is not as finicky as the old system, you might have a millimeter fudge factor, but getting it right on should be the goal.
The rest was simple. Break the frame at the belt split, install the belt and re-attach the splitter bolt and tighten that baby up. Slide your wheel forward and get the belt on the cogs. Slide the wheel back to tension the belt and tighten the axle bolts. Reset your disc brake if needed, attach your Nuvinci shifter cables and go ride!
With several rides, including a couple of wet and wild beach rides on the belt drive fat-bike I can say it is great! The drive has weathered sand, seaweed, being completely submerged and has not complained once. The 39-24 cog combo is perfect for the beach with low enough gearing to make spinning through the soft stuff possible while having enough top end to cruise. Plus, cleanup post ride is very easy. Note that on transition stages on the road I can top out at about 20mph with this drive ratio.
We will do a longer term testing report down the road. See ya then!