Aleksey

I have a classical German city bike of 70-es with Sturmey Archer 3 speed rear hub.
I live on the top of the hill so it is difficult for me to ride home :-)
Will it be more easy if I replace the hub with Sturmey Archer 8 speed XRD8 ?
I have some doubts because they write that "Gear 1 - 100% (Direct Drive) " and maximum sprocket is 25.
I already changed the rear sprocket to 22 but I want more effect.
I want to go uphill very slowly but very easy. :-)
If XRD8 will not help then which hub could work for this case ?

Aleksey

Actually I tried to look everywhere myself and it seems like the choice is just from 3 rear gear hubs with pedal brakes and downshift:

SHIMANO

NEXUS Internal Geared Hub Coaster Brake and Disc Brake 8-speed SG-C6001-8CD
Gear ratio_Total 307%
Gear ratio_1 0.527
Gear ratio_2 0.644
Gear ratio_3 0.748
Gear ratio_4 0.851
Gear ratio_5 1
Gear ratio_6 1.223
Gear ratio_7 1.419
Gear ratio_8 1.615

SG-C3001-7C
Gear ratio_Total 244%
Gear ratio_1 0.632
Gear ratio_2 0.741
Gear ratio_3 0.843
Gear ratio_4 0.989
Gear ratio_5 1.145
Gear ratio_6 1.335
Gear ratio_7 1.545

Sturmey Archer

RX-RC5 5 Speed Coaster Brake Rear Hub
• Overall Range - 243%
• Gear 1 - 64% (Gear 2 - 25%)
• Gear 2 - 80% (Gear 3 - 25%)
• Gear 3 - 100% (Direct Drive)
• Gear 4 - 125% (Gear 3 + 25%)
• Gear 5 - 156% (Gear 4 + 25%)

And the Sturmey Archer is more expensive and more difficult to buy so in fact we have 1.5 producers of such things on the planet.

Andrew R Stewart 

Can you change out the chain ring to a smaller one? Way back SA was still made in England, I was suggested to have my SA AW 3rd gear be the flat road choice and 2 and 1 were for going slower/up hills. I have followed this since. Andy

Aleksey

Yes, perhaps this will be the next step if I do not invest in a new hub.

tyrion

If you're not going to change sprockets, you have to look at the gear ratios of the hubs. For instance this 3 speed hub

https://www.sturmey-archer.com/en/products/detail/s-rc3

has a lower gear ratio than this 8 speed:

https://www.sturmey-archer.com/en/products/detail/x-rd8

A more useful way to thing about is: the hub gives you a range of ratios, and the sprockets determine where that range is located. You can get lower gears with your existing hub just by changing the chainring (front sprocket).

Aleksey

I started from increasing the back sprocket.

Wilfred Laurier

In my experience, the Shimano hubs are reliable and probably readily suited to your needs.

Someone in this thread posted a list of the drive ratios on available hubs, the Shimao Nexus 8 has the lowest drive ratio on it's lowest gear. These are also very efficient and robust drive systems, in my experience.

I don't know about availablity but those are made with a variety of OLD sizes and brake types. Get the correct one laced into a beefy rim by a bike shop. Multiple gearshift options as well with these hubs.

GamblerGORD53

There is NO chance a new hub besides a 3 spd that will fit on that old bike.
I have those hubs, except for either 8 speed. I ride the 3 speed at 48 GI and get up 10% hills just fine.
The SA 5 and Nexus 7i have the same range. I rode them at 34 to 84 GIs for a while this spring, they do climb way better that way.
But I hate going slow and made them 38 to 92.5 GI or 46 to 110 or 115 GIs.
Coaster brakes are dumb anyway, get a SA drum brake.
The SA 8w has a 33% gap at both ends, so it's actually not great for hills. 1st gear at 35 GI, then 2nd at 45 GI or so, is higher than your low now. It is good that 1st is direct drive. This example is for 32/ 25T. One guy here uses 30/ 25T.
Shimano roller brakes are dumb for sure, with a lot of drag and heat.

tcs

KMC makes 27T and 30T sprockets (the "Shimano" will fit your Sturmey-Archer AW hub.)

dsbrantjr

This bicycle gearing calculator will allow you to compare two different drivetrain setups. It supports many types of internal-gear hubs: https://www.kstoerz.com/gearcalc/compare/