Risk of water entry to Sturmey Archer hub through hollow axle

[Yim]

I have a Sturmey Archer CS-RK3 hub on my recumbent bike. The bike has sort of unusual rear forks that sit well below the chainstay, I think so that the chain doesn’t pass through the rear triangle:



Because the dropouts are below the chainstay where the cable stop is, the gear selection chain runs upwards out of the hub’s axle. I assume it’s intended to run slightly downwards or at least horizontally. I’m concerned that if I get caught in a downpour then water might get into the internals of the hub through the axle, either carried down the chain like a wick, or probably more likely by pooling inside the nut cover. The cover is only open where the chain comes out, so if water gets in that upward facing opening it can’t drip out again and has nowhere to go except into the axle.

Is this a realistic concern? I have a few ideas on how I might fix it: simplest would be getting rid of the nut cover, though that would leave the axle vulnerable to direct splashes and water running down the chain. Or I could drill a hole in the lowest sitting part of the cover to let water out. Or I could try to mount the cable stop lower than the axle, either by hanging some sort of support from the chainstay or using an SA fulcrum lever.

The fulcrum lever seems like the best solution, but I’m not sure if it will push the guide nut too far out on the axle for it to securely hold the wheel on.



It looks like there are a couple of spare mm of thread, although the inside of the nut is threaded even around the edges of the holes. I’m not sure how wide the fulcrum lever is.

Can anyone advise? Am I overthinking this?

[pjclinch]

Look at a Brompton with a Sturmey/Brompton rear 3 speed hub (which have the toggle chains pulled from above) and then stop worrying too much about it!

I did have a rusty toggle chain snap recently when I had the back wheel off to change the sprocket, but it was about 25 years old...

Pete .

[Carlton green]

Can anyone advise? Am I overthinking this?

imho yes, you’re overthinking it.

Whilst responding one of the photos seems to show the knurled locknut on the chain adjuster is not ‘locked’ against the adjusting barrel - it should be.

The rod through a hollow axle arrangement has been used for many decades and current arrangements are less exposed than was once the norm. I’ve never heard of water ingress being an issue, but I understand your concern and on my own bikes the rod is greased to impede the ingress of water and other unhelpful stuff. Mine is likely an unnecessary precaution, but it’s easy to do and it keeps my mind at ease - perhaps you might choose to do similar.

As an experiment you could try using a watering can over the connection and control chain, and then check for water ingress into the cover.

The SA three speed hub is pretty tough, even if you ended up with a bit of water ingress the likely consequences - if any - are minor.

[cycle tramp]

I think.. you're over thinking it. However if I was concerned about it I would drill a hole in the bottom part if the plastic cover just to let any water out.

[rogerzilla]

The slots for the sliding axle key are in line with the dropout slot so it is rare for water to get into the internals except by total immersion:

https://www.sjscycles.co.uk/hub-spares/ ... mm-hsa621/

Unless you have a SA hub with an indicator that protrudes from the LH end of the axle (some of these, like the AM, are best converted to an AW clutch and toggle anyway), using an acorn nut on the LH is preferable.

The rod of the toggle should be *lightly* greased or oiled with a thick oil. You don't want globs of grease inside the axle where they might trap water.

[Brucey]

I have always held the view that if there is not hub lubricant coming out here, there probably isn't enough of it in the hub. IME water can enter the hub via this hole, but it takes diligent abuse to do it. For a while, my hack bike used an FW hub, but fitted with an AW control toggle, effectively making it a medium ratio 3s hub. There was no control rod of any kind on the LHS, within the hollow axle (I'd had a close-fitting pushrod there previously, for many years). Because the bike lived outdoors, eventually water did get into the hub via the hollow axle. Even then, I daresay I could have prevented it's entry by use of waxoyl or other hydrophobic coating.
In your case I would consider it prudent to drill a drain hole in the plastic cover and to apply waxoyl to the metal parts, despite the fact that you probably don't really have much to worry about.

[plancashire]

Find a small thick piece of rubber, cut it into a disc about 10mm diameter then push a needle through the centre. Push this onto the puller chain and pull it downwards so it forms a downwards-facing cone. It will shed most of the water running down the chain. Some grease around the axle end will do the rest.

[Yim]

Thanks for the responses, puts my mind at ease a bit. I’ve checked the adjustment and tightened the locknut (I’m sure it was locked before but maybe not tightly enough), thanks Carlton green. When I get a bit of spare time I’ll drill a hole in the bottom of the cover and grease the indicator.