Cassette

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KM2
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Joined: 23 Oct 2008, 5:38pm

Cassette

Post by KM2 »

Does a 7 speed free hub take an 8 or 9 cassette, if they are narrower?
rjb
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Location: Somerset (originally 60/70's Plymouth)

Re: Cassette

Post by rjb »

You can fit 8 sprockets from a 9 speed or 9 sprockets from a ten speed cassette. You will need 9 or 10 speed shifters if you want indexed shifting.
8 or 9 sprockets can be installed on a 7-speed hub, using 9- or 10-speed spacing
from Sheldon Brown.
https://www.sheldonbrown.com/speeds.html
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
crazyfrog
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Joined: 8 Jun 2023, 10:13am

Re: Cassette

Post by crazyfrog »

rjb wrote: 8 Jun 2023, 8:42pm You can fit 8 sprockets from a 9 speed or 9 sprockets from a ten speed cassette. You will need 9 or 10 speed shifters if you want indexed shifting.
8 or 9 sprockets can be installed on a 7-speed hub, using 9- or 10-speed spacing
from Sheldon Brown.
https://www.sheldonbrown.com/speeds.html
It’s possible he’s got a spacer on his freehub.
NickJP
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Location: Canberra, OZ

Re: Cassette

Post by NickJP »

Here's one of my bikes that has a 7-speed hub (a 1990s Shimano Deore DX) on which I used a 9-speed cassette with the smallest cog discarded. So the 11-32 cassette became a 12-32. I had to replace the 11t lockring that was provided with the cassette with a 12t lockring, as the 11t one was too small an outer diameter to engage with the 12t cassette cog. That was the only faffing around needed to get it to work.

The only caveat is that the freehub needs to be one that is internally threaded at the end to take a lockring. Some of the oldest 7-speed ones require a uniglide cassette where the smallest cog is threaded to hold hold the cassette on - the Deore DX freehub that I used here here is both internally and externally threaded, to take either a lockring or a threaded cassette cog:
IMG_0109.jpg
KM2
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Joined: 23 Oct 2008, 5:38pm

Re: Cassette

Post by KM2 »

I’d better check for spacers etc. it’s a Sachs 3 by 7 hub gear with cassette.
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531colin
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Location: North Yorkshire

Re: Cassette

Post by 531colin »

Is there anything to suggest that these Sachs 3 speed hubs were ever built to take more than 7 speeds?
steve.y.griffith
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Location: North London

Re: Cassette

Post by steve.y.griffith »

As Sachs copied Shimano spacing I think you will struggle when I tried an 8 speed on a7 Shimano I could not screw the locking . However one option is fit an 8/9 freewheel body
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Sum
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Joined: 17 Jul 2010, 9:13am

Re: Cassette

Post by Sum »

KM2 wrote: 8 Jun 2023, 8:28pm Does a 7 speed free hub take an 8 or 9 cassette, if they are narrower?
I think so. An 8 speed cassette should fit if you remove a sprocket and a spacer. The sprocket spacing is close enough between 7s and 8s that it might work with existing 7s shifters. I've ran a 7s cassette with 8s shifter for a short while and that worked.

Ditto for a 9s or 10s cassette if a sprocket and spacer is removed, as already posted by rjb and NickJP. This may be best done by removing the smallest sprocket, as described by Sheldon here (also includes a brief mention of a Sachs 3 x 7 hybrid-gearing hub).:
https://www.sheldonbrown.com/k7.html#897

Sheldon mentions that you may need then to replace the second sprocket with one that has a built-in flange, but NickJP seems to have gotten away with simply using a larger lockring.

NickJP warns that some 7s freehubs are uniglide, rather than hyperglide. Also some 7s hyperglide freehubs are not the modern compact design and won't work with a 11t sprocket. According to John Allen, this may apply to the Sachs 3 x 7:
https://www.sheldonbrown.com/sachs-inte ... #favorites

However, if you're not using the 11t sprocket, then this may not be a problem.
KM2
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Joined: 23 Oct 2008, 5:38pm

Re: Cassette

Post by KM2 »

Thanks very much. I’ll have to give it some thought, probably not worth it for a single sprocket increase but maybe driven to do something as the quality of 7 cassettes is likely to be low and it’s a tandem.
Thanks again
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531colin
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Location: North Yorkshire

Re: Cassette

Post by 531colin »

Hang on, re-wind a minute.....
You have a Sachs 3x7 on a tandem.....probably not specified for tandem use?
What does the 3 speed do? 1 gear will be direct drive. then you may have 1 gear geared up a bit and 1 gear geared down a bit; or you may have 2 gears higher than direct drive, or 2 gears lower than direct drive....depends on the design.....I don't know.**

where are you going with the extra gear? do you want lower gearing or higher gearing?
What are the current chainwheel(s) and sprockets?
Rohloff won't warranty their hub gear if you drive it at less than 2:1 gearing, ie 42 chainwheel, 21 sprocket, and thats for a solo
What are the limits for Sachs?

What are you suspicious of with 7 cassettes? tooth profile? hardness?

**Rohloff gear 11 is direct drive, you have 12 to 14 geared up, and 1 to 10 geared down
KM2
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Joined: 23 Oct 2008, 5:38pm

Re: Cassette

Post by KM2 »

The Sachs is standard for a bike Friday, either single or tandem.
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