SRAM, sturmey hub

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KM2
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SRAM, sturmey hub

Post by KM2 »

On a three speed hub with 8 cassette body, what is the hub ratios from the middle gear? I think it is 24% down and 33% up but memory is fading on that.
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Mick F
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Location: Tamar Valley, Cornwall

Re: SRAM, sturmey hub

Post by Mick F »

25% down and 33% up is the usual for a 3sp. Direct drive for 2nd.

This one's mine.
https://www.sturmey-archer.com/en/produ ... rf3-silver
Mick F. Cornwall
KM2
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Joined: 23 Oct 2008, 5:38pm

Re: SRAM, sturmey hub

Post by KM2 »

Thanks Mick.
brumster
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Re: SRAM, sturmey hub

Post by brumster »

Mick F wrote: 3 Feb 2023, 4:05pm 25% down and 33% up is the usual for a 3sp. Direct drive for 2nd.

This one's mine.
https://www.sturmey-archer.com/en/produ ... rf3-silver
Gear steps of 33% and 33% is quoted on the spec.
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Chris Jeggo
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Location: Surrey

Re: SRAM, sturmey hub

Post by Chris Jeggo »

brumster wrote: 3 Feb 2023, 6:59pm
Mick F wrote: 3 Feb 2023, 4:05pm 25% down and 33% up is the usual for a 3sp. Direct drive for 2nd.

This one's mine.
https://www.sturmey-archer.com/en/produ ... rf3-silver
Gear steps of 33% and 33% is quoted on the spec.
25% down and 33% up from middle (2nd) is the same as 33% up from bottom (1st) and then 33% up again to top (3rd).
rogerzilla
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Re: SRAM, sturmey hub

Post by rogerzilla »

That's for an AW or SRF3. There are vintage SA hubs with different ratios but you won't see many.

The SRAM 3-speed has a very slightly wider ratio than 33% but you are unlikely to notice much difference when riding.
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Mick F
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Location: Tamar Valley, Cornwall

Re: SRAM, sturmey hub

Post by Mick F »

brumster wrote: 3 Feb 2023, 6:59pm
Mick F wrote: 3 Feb 2023, 4:05pm 25% down and 33% up is the usual for a 3sp. Direct drive for 2nd.

This one's mine.
https://www.sturmey-archer.com/en/produ ... rf3-silver
Gear steps of 33% and 33% is quoted on the spec.
Screenshot 2023-02-04 at 18.41.41.png
Mick F. Cornwall
brumster
Posts: 510
Joined: 8 Sep 2009, 7:50pm

Re: SRAM, sturmey hub

Post by brumster »

Mick F wrote: 4 Feb 2023, 6:42pm
brumster wrote: 3 Feb 2023, 6:59pm
Mick F wrote: 3 Feb 2023, 4:05pm 25% down and 33% up is the usual for a 3sp. Direct drive for 2nd.

This one's mine.
https://www.sturmey-archer.com/en/produ ... rf3-silver
That's me told then ! Thanks for explaining.😁

Gear steps of 33% and 33% is quoted on the spec.
Screenshot 2023-02-04 at 18.41.41.png
KM2
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Joined: 23 Oct 2008, 5:38pm

Re: SRAM, sturmey hub

Post by KM2 »

I’m fine now. Thanks for all the replies.
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