Experience with Sturmey-Archer RF3 3spd Cassette Hub?

General cycling advice ( NOT technical ! )
sk716
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Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby sk716 » 30 Apr 2020, 3:34pm

Hi,

I'm thinking about installing a Sturmey-Archer RF3 3spd Cassette Hub to further widen gear ratios on my bike. Interested in hearing from folks who're using or repairing these hubs. Any positives/ negatives, especially around durability/ robustness. Thanks a lot!

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Mick F
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby Mick F » 30 Apr 2020, 5:04pm

I have a CS-RF3 on my Moulton with a Shimano 105 10sp cassette.
http://www.sturmey-archer.com/en/produc ... rf3-silver

I wanted one in 28h as Sturmey Archer say they make them in 28h, but the only hole-count they import into Europe is 36h so I had to buy a new rim as well.

The hub is excellent.
I really don't understand why they're not commonplace on bikes, other than some folk are worried(?) about weight as the hub is on the heavy side.

Main issue I had was fitting a suitable gear control on my dropped handlebars.
The hub pull ratio is designed for a left-hand MTB triple thumb shifter ....... which are the wrong diameter for a dropped handlebar.

I went for a 'bar end friction shifter.
The 3sp system is tight cable for 1st and sack cable for 3rd.
The 2nd gear needs to be aligned on the yellow mark on the toggle chain, and if you set the shifter to be inline for 2nd it's easy!
Never an issue at all.

I really don't understand why these hubs aren't more popular as they give a whole new ability for gear changing and available ratios, and they're not that expensive either.
Mick F. Cornwall

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Mick F
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby Mick F » 30 Apr 2020, 5:11pm

PS:
http://www.sturmey-archer.com/en/produc ... rf3-silver
This shows the LH end with one nut.
The hub arrives with two nuts.

With two nuts the OLN is 135mm
Remove one nut, and the OLN is 130mm

I removed one nut to make it 130mm.
Mick F. Cornwall

sk716
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby sk716 » 30 Apr 2020, 6:00pm

Thanks a lot!

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Tinnishill
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby Tinnishill » 30 Apr 2020, 6:29pm

I fitted one of these on a Tern Node and described it here;

viewtopic.php?f=5&t=107139&p=1060751&hilit=tern+node#p1060751

A couple of years further on and it’s been fine. I do have this niggling doubt, however, about the old Sturmey Archer injunction to never exceed a two to one ratio between chain wheel and drive sprocket. My biggest sprocket is 32 tooth and the chainwheel is also 32t, so am I over torquing the epicyclic bit ? Modern Sturmey Archer doesn’t seem to mention this sort of thing. I have had no indication of trouble but the thought does cause me an occasional worry.

It’s a nice, relaxed set up to ride, though.
Agitate, educate, organise.

sk716
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby sk716 » 30 Apr 2020, 7:16pm

Thanks, sounds great!

jimlews
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby jimlews » 30 Apr 2020, 7:36pm

Mick F wrote:I have a CS-RF3 on my Moulton with a Shimano 105 10sp cassette.
http://www.sturmey-archer.com/en/produc ... rf3-silver

I wanted one in 28h as Sturmey Archer say they make them in 28h, but the only hole-count they import into Europe is 36h so I had to buy a new rim as well.

The hub is excellent.
I really don't understand why they're not commonplace on bikes, other than some folk are worried(?) about weight as the hub is on the heavy side.

Main issue I had was fitting a suitable gear control on my dropped handlebars.
The hub pull ratio is designed for a left-hand MTB triple thumb shifter ....... which are the wrong diameter for a dropped handlebar.

I went for a 'bar end friction shifter.
The 3sp system is tight cable for 1st and sack cable for 3rd.
The 2nd gear needs to be aligned on the yellow mark on the toggle chain, and if you set the shifter to be inline for 2nd it's easy!
Never an issue at all.

I really don't understand why these hubs aren't more popular as they give a whole new ability for gear changing and available ratios, and they're not that expensive either.



Hi Mick,

Question regarding your friction shifter.

Aren't you always mashing gears when you try for second gear? Or are you using it as a two speed and never using second gear.

OK, that's two questions.

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[XAP]Bob
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby [XAP]Bob » 30 Apr 2020, 9:40pm

I use one on my trike as well, although it’s not been on there for a while as I have a hub motor there for commuting, then had to stop for medical reasons a couple of years ago :(

I basically treated it as a 5 chainring system (the normal three and +/-1 from each)
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby Brucey » 1 May 2020, 12:53am

Tinnishill wrote: ….I do have this niggling doubt, however, about the old Sturmey Archer injunction to never exceed a two to one ratio between chain wheel and drive sprocket....


where might this be writ, exactly? FWIW in old SA 3s hubs the usual limiting factor in hard use was that the sun pinion was riveted to the axle. [Modern SA hubs have one-piece axles which are an inherently stronger design; indeed you can upgrade an older SA AW hub with a new style, stronger axle. ]

re CS-RF3; I have seen one or two of these hubs blow up, and the cause of the blow-up appears to have been a crap gear cable, that wouldn't allow the hub to shift itself all the way into third gear. This resulted in the high gear clutch slipping and this wrecked the hub. (*)

The 'window' for second gear to be safely selected is quite wide, so you are unlikely to come to grief this way; IME the most likely time for a 'distress shift' is when selecting the low gear in the hub, which again has a very wide 'window'. [In essence the hub internals have been modified to allow a MTB RH shifter to be used, which has a much longer cable pull than is 'normal' for a 3s hub. The result is that gear 2 and gear 1 have a wider 'window' than in many other 3s hubs.]

Some models of shimano LH thumbshifter/bar end shifter (which are otherwise friction shifters) have a tactile detent in the middle position; one of these would be ideal for this hub, I would have said. However I don't think I've ever seen a list of shifters that have this feature; I don't think any of the current models do.

(*) if the high gear clutch -which has sharp edges- gets chipped, the fragments stand every chance of jamming the plunger pawls in the planet cage. To my mind this means if the hub slips in high gear, even once, then it should be stripped and cleaned, else reliable operation subsequently cannot be guaranteed.

cheers
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Mick F
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby Mick F » 1 May 2020, 8:55am

jimlews wrote:Question regarding your friction shifter.
Aren't you always mashing gears when you try for second gear? Or are you using it as a two speed and never using second gear.
OK, that's two questions.
These hubs don't need a back-pedal like the old hubs. Just take the power off for a second (or less).

The bar end shifter is aligned parallel with the drops in second. All the way down for third, and up as tight as it will go for first.

My shifter is this one.
https://www.sjscycles.co.uk/gear-shifte ... left-hand/

It moves downwards silently, and clicks when going upwards.
I did some detailed experimentation, and produced this.
Lever Clicks.png


As for the second part of your question, the bike tends to be in second gear mainly. This is "direct drive".
I have a triple chainset but because of having small wheels on the Moulton, the gear ranges available aren't wide enough for me. Fitting the CS-RF3 was a cheaper and easier solution.

First is used to extend the bottom gears for climbing the steeper hills, and third to extend the top gears for roaring down them.
The bottom gear is 16" which is excellent, but the top gear of 135" is a bit too high for some folk perhaps .......... but I love it! :D
Mick F. Cornwall

Brucey
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby Brucey » 1 May 2020, 10:20am

Mick F wrote:….These hubs don't need a back-pedal like the old hubs.....


old hubs don't 'need' a back pedal either. IME easing off as you describe works with every shift on pretty much every SA hub.

If there is a problem with this, it is that "legs can be clumsy" and not everyone actually eases off fully when they should.

cheers
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jimlews
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Re: Experience with Sturmey-Archer RF3 3spd Cassette Hub?

Postby jimlews » 1 May 2020, 12:56pm

I don't think that counting clicks is quite my 'thing'. Especially in the heat of the moment.

A bit of thread drift:
In the dim and distant past, using AM, AW, FW hubs, I used a top tube quadrant changer and when accelerating used to pre-select a higher gear, then just ease off the pedals and the hub would snick into the desired gear. Delightfull! Only worked on upchanges.

With the FW, I positioned a peg on the top tube, about 6" behind the quadrant, so I could lift the (bare wire) gear cable onto it to select first gear.
Much more positive than Sturmey's own four speed trigger. That always had to be held in first gear if the least bit worn; to stop it slipping out of gear.

Happy days.

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Mick F
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I could

Postby Mick F » 1 May 2020, 4:47pm

jimlews wrote:I don't think that counting clicks is quite my 'thing'. Especially in the heat of the moment.
You don't have to at all.

I did it because of the long thread about this hub before, and quantified the shift pulls required.

So long as 2nd gear is correct - or nearly correct as it's not critical with these hubs - 3rd is slack and 1st is tight.
You are supposed to align the yellow mark on the toggle chain for 2nd gear as the yellow mark exits the hollow axle.
My yellow mark is fading, and within a year, I reckon it will have worn away.

I know that when the shifter is parallel, it's in 2nd.
I also know that when the shifter is all the way up, the cable is tight.
Without the yellow mark, I could still set it up knowing how the shifter is all the way up when the cable is tight.

Simple.
Forget the clicks, it was just research.
Mick F. Cornwall