invisiblehand

Hmmmm ... so does this mean riding in "low" chainring/rear-cog combinations puts more stress on the internal hub? That is, does a 39t/16t combination puts more stress on the hub than a 52t/16t combination?

invisiblehand

Actually, I was wondering myself. Then again, there is a link in the previous post.

invisiblehand

BTW, Jur ... sorry to hear about your bad luck. I hope it works out for the best.

-G

EvilV

I suppose that anything that allows you to put more torque through the hub would increase its potential stress. Would that be right? If it IS right, a smaller front sprocket, or a larger rear one, would enable you to spin the legs hard and fast on a steep hill, and shoot up the hill. This potential to put power into the hub would possibly strain small parts more than higher gear ratios.

All of the above is a guess. I'm really just wondering aloud.

stevegor

When am I ever serious??.........

LittlePixel

Sheldon rocks - He was really helpful when I mailed him when I couldn't get the black collar off my UN-72 back in the day. I think he has a special email filter that favours bikes he likes so one is more likely to recieve some sage advice if it's about R20s than - say a Trek FX7100..

tcs

By-the-by, SunRace claims to have made some 20 changes to the three speed hub, some of which are supposed to make it even more robust/long lasting. Certainly the exploded diagram's part numbers list many differences between the old AW design and the new AW-NIG/SRF3.

TCS

tcs

I'm told SunRace Sturmey-Archer's grease is a synthetic gel, part number SA103A. Where a civilan might aquire some, or an 8 speed ball ring spanner, is unkown.

TCS

jur

Yeah, the SA103A is what is listed in the various manuals. I am going to use food-grade chain grease, it seems to have similar consistency.

I made the ball ring spanner from a piece of alum rectangular tubing and some hardened screws.

jur

Hmmmm... I just googled "lubricating gel." Not quite what I was looking for...

Sheldon Brown

The smaller the chainring, the more pull on the chain for the same push on the pedal.

The bigger the rear sprocket, the more torque on the hub for the same amount of chain pull.

Bikes with small wheels require less torque to drive the bike (but the have to spin faster.)

They also require less "power" from a hub brake, so hub brakes that are marginal on big-wheel bikes can work fine on small wheel bikes. A case in point is the Sturmey-Archer drums on my Greenspeed with 349 mm (16") wheels.

Sheldon "Moment Arm" Brown

stevegor

I wholeheartedly agree L.P.....I have found Mr. Brown a wealth of knowledge and only too happy to help....a bit different to the "elite and arrogant" snobbery one sometimes finds in racing cycles.

EvilV

The grease needs to be very slippy thin stuff. I have experimented with ordinary grease - the pedals went around like a fixy when coasting in top gear. Too much drag by far ( x10).

The real stuff is very lightweight.

I'm very happy just with a few drops of light oil now and then. My srf-3 has had no grease at all for a thousand miles - not even in the wheel bearings. Spin it up in top gear on a stand and it runs on and on like a perpetual motion machine. The back wheel spins longer than the front one which has grease of course.


Sheldon's website is a delight. Full of info about anything I ever need to know about bikes.


As for the Lubricating gel google surrprise, you get the same kind of thing if you google 'lubricant'. Considering the relative world demand for the two kinds of products, it tells you something about the interests of Internet users - or maybe Internet marketers.

jur

I wonder... I feel myself gravitating to using thin oil instead... the seals seem sufficient for oil... perhaps I'll put in an oil port a la EvilV.

invisiblehand

If you decide to take that route with an SA-8, I would be interested in the details.

Although the schematics for the 36-hole version do not quite match up with the 28-hole version of the hub.

EvilV

You can put the oil straight into the centre of the hollow shaft and let it run inside. The problem with that is that you can't really clean it of grit and stuff that may get into the axle and then get washed into the inner parts of the hub. I thought that a bad idea.

If you go for a port, I hope you'll execute it better than I did. I just used a hand held electric drill to put a 3mm hole in the shell. Then I tapped in a short bolt as a plug. It is horribly crude. I obviously did this without the gear unit inside teh shell. That way I could clean out the small bits of alluminium swarf from the drill.

The oil sticks around for ages in there - it doesn't need to be swimming in it, though I did try that and got messy wheels. Little and often is the best regime for oil.

jur

No hollow shaft on this one. A port is the only way. I have an old hub with a port lying around which probably will never see a wheel, I may use its port. Depends on whether I can drill a suitable hole in the hub in between the spokes. Maybe from the inside. All this depends on whether a spare part will ever reach me. In the interim I may revert back to 3sp, that wheel is gathering dust at the moment.

I have also seen oil ports on ebay recently.

maunakea

jur, search for a 90 deg. geared "elbow" fits in your drill chuck. Failing that, a flexible shaft. Drill on the bottom of the hub, so the swarf falls away from the workpiece. To take it one step further, run your shop vac hose as close as you dare, and if the hub shell is steel, run a little magnet (like as magnetized screwdriver tip) and a bent Q-tip around inside the new hole. Swarf is your enemy.

jur

Good tip on the elbow.

Swarf is the least of my problems right now - this hub is ally and stripped down to the shell so any swarf will be vanquished when I wash it upon receiving the spare part (still no word from SunRace).

jur

I have installed the 3sp wheel again, after washing everything internal and external, and put thin (Singer) oil in. I have to agree, it feels good. Tomorrow's commute will tell me how it will go.

I also washed the 8sp planet systems even cleaner, there was still gel in the sun gears, shown by drag on the gears. After washing, very little drag. I'm definitely going with thin oil for the 8sp also. I put all the internals back together, pending getting the spare planetary system, just to pop it in and ride (I hope).

Still no word from SunRace though.

EvilV

I'm surprised they haven't responded. When i asked for instructions from Sugino about how to secure my left hand crank after it came loose, they air freighted me instructions AND a new left crank within five days. It wasn't their fault either.

Don't you have any recourse to the seller of the Hub? I'm assuming it is quite new. In the UK you will almost always get a year's guarantee on new items. Some try to wriggle out by alleging misuse though, or offer to send it back to the manufacturer, but in law, the buyers recourse is to the seller. People don't always realise that here and can be fobbed off. Obviously, different legal systems do things their own way.

Don't be surprised if some of your singer oil comes out at first. It took me a while to realise how little was required.

jur

Yes, I also wrote to the seller (aebike) and they wrote to SunRaceUSA and copied me.

I had another look at the 8sp seals; the seal at the big ball race seems rudimentary, I wonder if I would lose the oil there. I'll see if I can find a description or I'll post some pics for opinions.

jur

Well I received the 'spare parts' hub from aebike this past Friday. It is a used hub and missing some external parts such as the LH cone and the shifting disc on the RH side. It had been laced to a wheel as the spoke holes showed marks.

Anyway I had trouble opening it since there was nothing to hold on to when unscrewing the ball ring. I finally accepted my son's suggestion to screw it to a piece of timber, only I used nails and hammered it to a board after using a hole saw for the LH side piece to lie in. That worked well enough, once I put in big enough nails for the job, not those sissy panel pins I tried first.

The gear mech looked relatively unworn, compared to mine. I debated just dropping it in whole or just replacing the broken part, I did the latter in the end, as I like the idea of the parts being broken in and therefore running smoother.

After putting the mech back together (nope, I had no parts left over ) I oiled it using light Singer oil. I still have to drill an oil port in the hub and am also waiting for new high quality bearing balls since the old ones show signs of wear.

I will probably reassemble it to the bike in a week or two.

Still no word from Sunrace Taiwan. I actually called them and got the email addr of someone in the co. to correspond directly with. No avail. I won't be pursuing that any further. But if I did, I could probably get together another fully working hub as the one sent to me from the US appears to be fine besides the missing parts issue.

EvilV

Great - keep us informed as to how it goes.

Simple Simon

This is a fascinating thread Jur- please tell us how it works out ... maybe 'in anger' up that climb that killed it

I totally agree - thats why I prefer this folding forums than the roadie ones .... there is much more new stuff here .... less BS and less testosterone (and any there is, is 100% self generated !).