jur

This weekend I took part in a social ride up the local peak, and about 2km from the top the hub made crunchy noises.

Full report here.

SesameCrunch

How old was the hub?

tgzzzz

Thanks for the good story, man. Lots of readers will be waiting to hear what you find inside the hub. I am bummed to hear about snow in Aus. I'd just never considered it.

jur

IIRC I bought it from aebike near the beginning of this year. About 9000km on it.

EvilV

Great report on Cycling Victoria forum Jur.

Does the SA 8 speed have smaller planet gears than the AW / SRF3? The structure in the 3 speed ones I have is very strong looking. I see what you meant on the other forum about being glad it didn't happen in the middle of Tasmania. Not exactly hand for spares I'd guess. Keep us informed if you would about the details of what broke and why. I need a full breakdown inquiry.

jur

Well it was as I feared - a broken planet gear. one of the gears split open on one side. Here are 4 images of the same thing:


This one shows the crack clearly.


Here at the bottom of the tooth there seems to be damage from a foreign body that got lodged in a tooth and probably caused the planet gear to split.


Clearer view of the tooth damage.

The foreign body seems still lodged in the tooth of the inner sun gear as it turns with some difficulty in some spots of the rotation. The assembly is riveted so I can't dismantle it further.

jur

The break was extremely difficult to find.

At first inspection everything looked just fine. I began to wonder if the problem was simply caused by cable adjustment and that in my blundering idiocy I forgot to check the adjustment.

But when I began to put the various parts back together and played with them I noticed the smallest planetary system was difficult to rotate. With a sharp pick I began to probe each gear groove to see if a tiny piece of grit was lodged in one of them, until I found one groove that felt very rough. To the naked eye I could see the groove looked a bit wider than its neighbours, and a magnifier showed the problem.

Nikon Coolpix did the rest.

jur

The damage seems to indicate that it wasn't excessive force or inadequate design that caused the break but rather it was contamination. And I doubt that it is a piece of the earth's crust that would be so hard as to not be ground to dust but force the gear to split open. It has got to be a piece of hardened steel.

stevegor

Jur,
Please reassure me that my 2 X 8 spd SA hubs will not do the same......

I read the posts about 6th gear being a pain at times, so I adjusted the setting and got it right, but now fifth gear is making noises like it's not just right, looks like more experimentation.
Maybe using the hub under extreme stress like hard climbing is not advisable, perhaps they're only meant for commuting??.

EvilV

Great analysis and investigation. I wonder how whatever it was got inside there. Do you think it was some junk that got in there at the factory, or something that broke off the unit? I'm hoping that the pounding you gave it broke something that smashed the planet gear, rather than random rubbish was left in there by the factory.

I can't imagine you have introduced anything yourself.

I've been inside my three speed SRF 3 a couple of times, I'll be damned careful after this that nothing comes adrift in there.

jur

During the first check-over I was looking for something that looked broken, but nothing turned up. Everything looks very good, no signs of mangling or damage anywhere until I found the crack. So at this stage I'm guessing the foreign body is something from the factory, but the planet gear rivets will have to be removed to be sure.

I don't think overwork was the culprit; even though I do ride very hard at times, I have a high cadence so the force on the gears wouldn't be that high. Of course sometimes climbing out of the saddle is involved but even there I have a tendency to 'dance' rather than grind. Having said that, there are a few places on my daily commute where grinding is required due to steepness. Anyway I would have thought that the gears are designed to withstand that.

I'll be writing to aebike about the guarantee issue, and make a call to Suntour in Taiwan about a replacement part. If Suntour don't want this sub-assembly I'll be drilling the rivets out to see what's going on in the sun gear.

Pine Cone

Sorry to hear about your troubles. As the owner of 3 bikes with this hub I am very interested in your findings.

Out of curiosity, what was your impression of the amount and quality of lube in the hub? I have always been suspicious of the "never lube" hype and have always figured the oil bath style of the older 3-speeds would flush away bits of dirt and broken bits of hub gears, etc.

9000 km is enough to break in the hub, but the pictures you posted don't seem to show excessive wear or other damage. I would like to think you could ride one 20,000 to 30,000 km before needing a re-lube or any other repairs.

jur

SA moved away from the oil-bath idea to a thin grease regime. If you compare the various manuals over the years, the early ones give instructions for oil through the port, while the later ones spec a thin grease. The later model 3sp hubs' oil seal labirynths were simplified to cut cost, presumably. The simpler seals are not enough to keep in oil but are OK for the grease.

The grease was everywhere when I opened it, so sufficient in quantity. It is presumably thin enough not to interfere with the pawl operation but is not runny like oil to go past the seals. It's like a gel, quite thin but doesn't run. My hub's grease was black, indicating metal particles from wear in suspension.

The purpose of lube is to prevent direct metal-to-metal contact. It seems to me that as long as it doesn't dry out and is enough to coat all parts, then no further maintenance would be needed for the normal life of the product. If we're talking extreme long use say several decardes, then one could expect the grease to have dried out to some degree and a washing and replenishing would be good.

pm124

That's some great riding on a broken hub! It sounds like it is under warranty, yeah? Repairing these hubs via drilling borders on heroic. Wouldn't it be easier to ask for a new hub and rebuild the wheel?

jur

Asking for a new hub is not without its own problems: I would probably have to send the hub back to the US which would require a wheel un-build, postage (expensive), wait ages for a replacement and then rebuild my wheel. Plus they would hit me for postage to send me the new hub. It is probably worth just buying a new hub outright. I have written aebike and Sunrace but I'm not holding my breath about hearing from Sunrace.

Getting in the sub-assembly would be far less costly all round, assuming it is available in the first place. I wouldn't have to drill to repair, that is just for inspection of the broken sub-assembly.

EvilV

I think the pictures you showed here should be all they need to see what has happened. No sense at all in demanding a chunk of scrap be transported half way around the world as evidence, surely. I hope you get decent treatment anyway. You ought to.

When they send you a replacement hub, it would be the obvious answer just to dismount the internal unit and pop it into the old shell. No need to rebuild wheel or anything, unless you suspect wear in the non-drive side bearing cup.

I think the manuals recommend servicing and re-greasing from time to time.

I've been running my SRF-3 on 10:30 engine oil for a good while now - about 1000 miles. I find that little and often is the best approach, or the oil comes out along the spokes. At first I was putting in about 6cc, but the surplus is spun out pretty quick. Now, I just put in about a half teaspoonful every couple of hundred miles, and it stays put. The old SA hubs didn't exactly have an oil bath either - they recommended two or three drops every month. Overfilling always caused the oil to escape - I know you know this because you have them yourself. As this oil thing was an experiment for me, I have taken out the internals to inspect them for dryness. There has always been a small amount of oil in the bottom of the shell, and the internals were completely soaked in oil, even after a couple of hundred miles. I could probably do it a lot less often than I have been, but it's so easy that there is no reason not to add a few drops. I drilled the shell and made an oil port which is sealed rather nastily with a short bolt screwed in a few threads.

The hub spins VERY easily with the oil regime. If I upturn the bike and pedal it up, the wheel spins on and on for ages, so there is no internal drag. It definitely spins on much longer than before. It changes very easily and is quieter than it used to be too.

Of course, there was no need at all to mess about like this, I just wanted to play around with the hub. As it was supplied it worked fine and is very robust, and quite straightforward in construction. A marvelous piece of kit really.

owenfinn

I had to bring my new Curve SL back to the LBS after only 50km. Same situation - a bad crunching sound from the SA 5 hub after a steep hill climb. I never saw the inside of the hub but the Japanese LBS owner said "something was cracked". He ordered a new hub - Dahon initially sent him the SA 3 speed. Finally, after waiting 3 weeks, I can pick up the bike complete with new SA 5 hub this Thursday. Just to be safe, I think I'm gonna now stay way clear of steep climbs whenever possible.

tgzzzz

Yet another reason to own multiple bikes.

EvilV

That's a rotten thing to happen with a new bike. I wouldn't let this put you off. A multi geared hub is designed for climbing hills and should easily cope. If it doesn't there's something wrong unless you are built like the Hulk and pounding the thing uphill at 25 miles an hour. A hub should normally cope with any NORMAL amount of pedal power. You've had a bad one, maybe with a foreign body inside that broke something. I wouldn't expect that to happen again.

Sheldon Brown

You don't say what sprocket ratio you were running, but given that you were on 20" wheels, I'm guessing that it was rather higher than would be used on a bike with full-sized wheels, so even though you appear to be a strong rider, you would actually be stressing it less than a rider with full-sized wheels (and appropriate sprocket sizes) would be doing.

That's SunRace, not SunTour. Totally different company. If you send 'em those pictures, I have no doubt they'll send you whatever parts you need or a new hub.

Sheldon "Epicyclic" Brown

jur

Ah. I thought they were the same. I have written to Sunrace in Taiwan and sent them the photos as well, and referred to the exploded diagram in the manual to which part I need for a repair.

The sprocket ratio is 42x25. Tyres are 406x50.

kb5ql

You got a reply from Sheldon Brown???? Jur is the king of the folding sub-forum...

jur

Heh heh, I cheated by emailing him...

stevegor

Who the heck is Sheldon Brown?..........................

jur

ha ha, very funny

* wonders if stevegor is being serious or not *