Hub gearing question

[Dec66]

A mate of mine, who doesn't cycle a great deal, is about to do L2B on his hybrid, which has Shimano Alfine 8-speed hub gearing.

I'm trying to work out what his ratios would correspond to in terms of the teeth on an 8-speed cassette if he had a derailleur setup (upfront is a single with 39 teeth). Would any clever people who understand this stuff be able to calculate rhat, based on the following ratios:

0.527
0.644
0.748
0.851
1.000
1.223
1.419
1.615

Ta

 

[raleighnut]

Put the info into this calculator, you can change all of the parameters but it has an nexus 8 speed hub in the built in options

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=2ahUKEwiO-v6qsqjdAhUIDcAKHUFWCe8QFjACegQICBAB&url=http://www.sheldonbrown.com/harris/gears/internal.html&usg=AOvVaw02pYO2olsvX3alikWM247K

 

[Dec66]

Put the info into this calculator, you can change all of the parameters but it has an nexus 8 speed hub in the built in options

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=2ahUKEwiO-v6qsqjdAhUIDcAKHUFWCe8QFjACegQICBAB&url=http://www.sheldonbrown.com/harris/gears/internal.html&usg=AOvVaw02pYO2olsvX3alikWM247K

It doesn't have the 8 speed Alfine in the drop down, sadly

 

[Moodyman]

I run Alfine 8 with 170mm cranks and 32mm tyres. Bottom gear is 31 inches and top is 93 inches. Broadly comparable to 50-34 x 9 speed derailleur set up.

Your friend/you can get the exact inches for every gear via Sheldon's gear calculator:

https://www.sheldonbrown.com/gear-calc.html

Edit: Nexus 8 and Alfine 8 are the same internally.

 

[Dec66]

I run Alfine 8 with 170mm cranks and 32mm tyres. Bottom gear is 31 inches and top is 93 inches. Broadly comparable to 50-34 x 9 speed derailleur set up.

Your friend/you can get the exact inches for every gear via Sheldon's gear calculator:

https://www.sheldonbrown.com/gear-calc.html

Edit: Nexus 8 and Alfine 8 are the same internally.

Ok ta, was sure I'd seen different ratios on the Nexus though

 

[Moodyman]

Ok ta, was sure I'd seen different ratios on the Nexus though

Nexus came out in several interations. The final version (Nexus Premium 8) has identical internals to Alfine 8. The only difference being the shifter and hub sealing - better on Alfine.

 

[mjr]

https://gear-calculator.com should have more modern hubs on its presets.

 

[TheDoctor]

Assuming your friend has the 18T sprocket, then that's like having a 9.5 - 29.1T cassette.
Specifically, a 9.5 11.6 15.3 18 22 25.5 29.1T cassette.
Those weird fractional values are why you don't normally try to work this out!
You're probably better off considering the actual gear inches, development or some other measure.
Or even just an overall percentage.
I'd be far more interested to know that if I geared for, say, a 25" first gear, then my top is 77" for that hub. Lower than 25" I may as well walk, and I can spin 77" up to about 30mph (but not for long!)