Use a Nexus nternally geared hub in rear wheel

Currently sourcing and building a ebike , at first was going to use the RM Element f/s bike but the more I read the more I want to make street ebike and leave the mnt bike as is for trail riding.

So I changed plans am now building up a mid 90's Qunitanna Roo panracer mnt bike frame have had for years most the parts are in a box it was missing a wheel set and the derailleurs / shifters.

Right now have a 26" front wheel / geared motor coming on the slow boat from China and since Im still needing the rear wheel went online when came across the Nexus internally geared hubs that cost about a $100 on eBay.
Ended up buying the nexus 4-spd version after reading it was durable and had high gears. I ride in 46 - 12T 90% of the time as it is without adding a motor.



This is the one I picked up it weighs 1370 gr / 3lbs without the roller brake on ( which it didn't come with and I don't want )
When i did the math using the weight weenies site I will be breaking even with the many removed parts and the added heavier hub and single grip shifter.

The Cranks have a 53T chain ring in them now it will stay and I'll remove the two other chain rings.
It works out to 3lbs of weight off in XT gear parts and 3lbs of weight on from a Hub and single gear changer.

The hubs on order now , the cool part is that 3lb hub will balance out the feel from the 5lb 250/350w geared from hub motor making for a well balanced / handling ride.

Using Sheldon Browns online gear calculator I found that my current rides 4th gear with a 46T front chain ring matches what that hubs 1st gear will be like using the 19T sprocket that in it and a 53T front ring.
To get a feel for what the gears will feel like , on a ride home today I started off in 4th gear and noted it took off quick fast until 15Kmh when the speed stalled due to leg spin , it seems like a a good road 1st gear to get to speed fast before engaging the flux drive

As a comparison a few normal bikes gear ratios
a 53/11T gear ratio = 9.4
A 19/53T ratio = 5.2

here the Nexus 4 speed ratios using 19/53T gears

4th = 10

3rd = 8.1

2nd = 6.7

1st = 5.4

The hub is in and weighs in at 1420 grams / 3.13 lbs which feels beastly in the hand hope it feels better on the bike.

Since last post discovered need to use a chain Tensioner as the frame has vertical drop outs. So picked up the shimano alfine ( internal hub ) chain tensioner.

The Alfine chain tensioner allows the use of two front chainrings with a max tooth difference of 16 between them.
So I will be using the bike with a 39t and 53t front rings with a 16T or a 19T rear sprocket ( the smallest sprocket shimano suggests to use with the hub )



With a 16T rear at 60 rpm at a relaxed 60 RPM vs speed in Kmh

39 Ring
1st) 4.6 = 18.2
2nd) 5.7 = 22.6
3rd) 6.9 = 27.2
4th) 8.4 = 33.5

53 Ring
1st ) 6.2 = 24.7
2nd) 7.7 = 30.7
3rd) 9.4 = 37.0
4th) 11.5 = 43.5

At a 100 rpm top gear was 75 kmh ..

Pretty high gears so will install the 19T sprocket first to try with its more reasonable speeds / gearing.

19T rear sprocket top speed

60 rpm = 38.3 kmh
100 rpm = 63.8 kmh