Sturmey Archer SRF3 hub crunching & slipping.

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Mick F
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Re: Sturmey Archer SRF3 hub crunching & slipping.

Postby Mick F » 28 Jun 2020, 9:52am

Jdsk wrote:PS: How can I make that screenshot readable inline? Thanks.
Copy and paste.



Cons
Not NIG!
Pros
None.
This is NOT the NIG version. This is the original and very dangerous slipping-into-netural AW hub which, in my humble opinion, was never fit for purpose and should never have made it off the drawing board.

SJS Customer Service:
It's true, this IS NOT the NIG version (no intermediate gaps?) this is the design that remained pretty much unchanged from 1936 until some time around the 1990s when the NIG upgrade slipped quietly into production. Many millions of miles have been ridden on hubs with this design, it is however essential to a) correctly adjust the cable b) know HOW to change gear, easing off the pressure or better still momentarily pedalling backwards.
Mick F. Cornwall

Brucey
Posts: 39522
Joined: 4 Jan 2012, 6:25pm

Re: Sturmey Archer SRF3 hub crunching & slipping.

Postby Brucey » 28 Jun 2020, 10:25am

Well it looks like SJS screwed up. Surprising to me because you can tell at a glance if it is a NIG AW hub or not; for example the driver splines are a different length.

Image
pre-NIG AW; long driver splines, lockwasher on RH cone

Image
short driver splines, no lockwasher on RH cone (in recent years)


FWIW SA didn't "quietly slip NIG hubs into production in the 1990s"; they launched different models which were NIG type or not, and sold them in different markets. They continued to manufacture the pre-NIG AW hub right up until production ceased in Nottingham; I have seen examples of pre-NIG AW hubs with date codes in year 1999/2000. [There are plenty of LBS owners and mechanics who think that SA made a serious mistake in stopping production of the pre-NIG AW; to this day they will happily build a wheel using an old AW hub for a client safe in the knowledge that it is extremely unlikely to get broken and it is easily fixed should it ever occur. ]

The only reason SA started to make NIG hubs at all was that one of their customers was daft enough to use an AW-based coaster hub as a brake, no, the only brake on the bikes they built. Never mind that the 'dangerous fault' which means the brake doesn't work properly also means that you won't ever get going in the first place.... :roll:

If you let a pre NIG hub get out of adjustment and it starts to slip in second

a) to start with it will usually only slip under high pressure, you still get some drive rather than none and
b) simply pulling the gear lever will always give you a gear that allows forward motion at any pedal pressure

It is therefore far less 'dangerous' than (say) a chain that is slack enough to come off, or that might not accomplish a gear change, or that might get itself similarly out of adjustment and fail to provide consistent drive. So that is arguably less 'dangerous' than any bike using derailleurs, and less 'dangerous' than the majority of other bikes with slack chains. IIRC in Denmark, they let folk ride around with just one brake and that is usually a coaster brake; if the chain gets a bit slack and comes off, no forward motion, and..... no brakes! But apparently that is 'normal'..... :roll: And a hub that signals to you that it is out of adjustment as clearly as possible before the daftest rider smashes it to bits isn't.

Or something.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

a1b2c3

Re: Sturmey Archer SRF3 hub crunching & slipping.

Postby a1b2c3 » 28 Jun 2020, 11:06am

Edited.
Last edited by a1b2c3 on 1 Jul 2020, 5:52pm, edited 1 time in total.

a1b2c3

Re: Sturmey Archer SRF3 hub crunching & slipping.

Postby a1b2c3 » 28 Jun 2020, 11:14am

Edited.
Last edited by a1b2c3 on 1 Jul 2020, 5:51pm, edited 1 time in total.

Brucey
Posts: 39522
Joined: 4 Jan 2012, 6:25pm

Re: Sturmey Archer SRF3 hub crunching & slipping.

Postby Brucey » 28 Jun 2020, 12:29pm

a1b2c3 wrote:So, while in the neutral position, the coaster brake couldn't be operated on the AW (AWC?) coaster hubs? …


SA have included a tricoaster in their range since 190-something. The only version made from 1936 until some time in the 1980s was non-NIG AWC type and the brake would only work when the gear (any gear) was selected. This was OK for forty years or so until it suddenly wasn't, and thereafter SA mainly introduced new NIG models .

...A slack chain can be seen. The "pre NIG" AW hubs slip without warning in my experience. When using hub gears or single speed hubs on frames designed for them, such as roadsters, BMXs, there is often a contraption that maintains chain tension. In conjunction with a full chain case, maintenance is minimal.


if the hub is out of adjustment this can usually be seen too. I've been riding bikes for over fifty years and I still can't -not with any certainty- tell the difference between a slackish chain that will and won't unship. However I can see the gear adjustment on a SA 3s hub, and even if it is obscured in some way I know that if the control rod will pull further out (by ~1mm or more) when first gear is selected, the adjustment is likewise bad. In use, on a 3-2 downshift you can feel if the drive picks up well before the shifter clicks into position and that tells you if the hub is out of adjustment too. Probably there are things about Sachs/SRAM hubs that are 'obvious' if you have been riding one all your life; it seems pretty obvious to me when a SA hub is starting to get out of adjustment.

Chain tensioners should not be used on machines with coaster brakes and they are rarely used inside chaincases. I am a fan of chaincases but IME the chain can still get slack enough inside one that it will unship, only you can't see how slack it is; the chain usually starts to rattle well before it is very likely to unship but some folk may regard that as 'normal' and carry on riding anyway.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~