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Old 11-26-07, 06:52 AM   #76
tgzzzz
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On my Swift I can average 30.1km/h to work - it is much faster.
Is the big difference in ET mostly due to the weight differential, Swift to modded-but-still-heavy R20, or would you credit the efficiency of the Swift, i.e. the upgraded wheels & hubs/narrow tires, less drag of the derailler compared to the SA8 hub, maybe more aero positioning, ...?

On the hub immersion deal, I'm dissapointed to read of rust after one incident when we know your "new" hub was full of oil. The old 3 speeds were indestructable in comparison.

When I had the LBS install my sealed BB, she made a big point (too big I thought at the time) about NOT washing the bike. I thought she meant because of the BB, but what's the big deal if it's sealed? Now I wonder if she was warning me about the poor sealing of the SA8 hub. I live at the beach. Rinsing things is a way of life. I don't ride my new DT on the beach, however. It's too cool. And I have my passed-over hybrid for that.
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Old 11-26-07, 05:39 PM   #77
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Originally Posted by tgzzzz View Post
Is the big difference in ET mostly due to the weight differential, Swift to modded-but-still-heavy R20, or would you credit the efficiency of the Swift, i.e. the upgraded wheels & hubs/narrow tires, less drag of the derailler compared to the SA8 hub, maybe more aero positioning, ...?
I don't think there is one single thing that makes all the difference. The much lighter weight would be a big thing, accelerating all that extra mass on the R20 tends to tire me and I have therefore less energy left over. But the other items, ie no suspension soaking up some energy, thinner tyres so more aero (this is true of the whole frame, really, especially the forks), and drivetrain efficiency all play their part. Another item where derailers shine is in being able to shift under load - you can just keep pedalling with just a small momentary easing off, whereas with the SA hub you need to stop pedalling for a moment.

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On the hub immersion deal, I'm dissapointed to read of rust after one incident when we know your "new" hub was full of oil. The old 3 speeds were indestructable in comparison.
Well perhaps it is not reasonable to expect labyrinth seals to keep water out under those severe conditions. I was disappointed too. Hopefully the silicone grease will tend to mix less with water and not form an emulsion which will cause rust.

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When I had the LBS install my sealed BB, she made a big point (too big I thought at the time) about NOT washing the bike. I thought she meant because of the BB, but what's the big deal if it's sealed? Now I wonder if she was warning me about the poor sealing of the SA8 hub. I live at the beach. Rinsing things is a way of life. I don't ride my new DT on the beach, however. It's too cool. And I have my passed-over hybrid for that.
I wash my bikes but take care not to direct a hard water spray near the bearings area. In fact I usually use a bucket with sudsy water and a paint brush, and use a compressor to blow it dry, again not directing an air jet at the bearing seals.
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Old 11-27-07, 08:04 AM   #78
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Well perhaps it is not reasonable to expect labyrinth seals to keep water out under those severe conditions.
I hadn't heard of this kind of seal but a quick turn to Wikipedia fixed that. Interesting indeed. And to build a hub with a water/oil tight seal adds a lot of friction apparently. I suppose that's why it was filled with the higher viscosity gel-type lube initially. Most of us would never notice the higher friction. Look for my hub in your mailbox along with Stevegor's at maintenance time.
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Old 11-28-07, 09:46 PM   #79
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Someone wrote:

"...it was filled with the higher viscosity gel-type lube initially."

The "gel-type lube" is more commonly called "grease." ;-)

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Old 11-28-07, 09:57 PM   #80
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Someone wrote:

"...it was filled with the higher viscosity gel-type lube initially."

The "gel-type lube" is more commonly called "grease." ;-)

Sheldon "Cyclexicographer" Brown
Ah, but you haven't seen this stuff. It doesn't draw threads or peaks like common grease. It feels very 'thin' like oil yet doesn't run like oil.
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Old 04-28-08, 10:44 PM   #81
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My R20's SA8sp hub is proving very problematic. The bearings are all rusted up again. I fixed this a previous time after freshly rebuilding the hub. This morning I thought I might take the R20 for commuting seeing that the weather was wet, so I tested the hub action and it sounds like it's grinding rocks so bad it is. I haven't ridden it for a while now since I was using the Swift for commuting in preparation for the Fleche-Opperman 24h trial.

Looks like the 3sp wheel is going back on. I am a bit dis-hearted by my lack of progress on this hub. Not sure what I'm doing wrong, because the Mini's hub is just fine (but that one hasn't ridden in the wet to the same degree). I feel like ditching the hub. Nothing is worth that much maintenance.
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Old 04-29-08, 12:25 AM   #82
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I wish I read this post long ago. I took my Downtube VIIIH onto the beach two weeks ago, since then, it started to have some grinding sound, though, its quite and not exactly noisy, its making me paranoid.
I called one of my LBS to have it serviced, but I was told they don't do Internal gear hubs. I'm afraid the other LBS would say the same.
It still shift and works fine, it just have the anoying sound. I hope this is not the beginning of its end yet, as I really like this bike.
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Old 04-29-08, 02:00 AM   #83
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Sad reading this when Sheldon passed away recently. I'm relaively knew to the cycling forum but soon learnt who this wonderful character was. 63 was quite young really, very sad.

When I spoke to Steve Parry the other week in the UK he advised against modifying a Brompton with an 8 speed SA hub and that they are prone to breaking within 6 months in some cases. I guess it isn't just the early models and the quality isn't as good as the older SA hubs since they transferred production to the Far East.
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Old 04-29-08, 11:37 AM   #84
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From the failures posted so far, the failures seem to be attributable to poor metallurgy for the planet gears and planet cage. The suns/planets need to be made of good hardened steel, with very careful machining to avoid stress concentrations. The planet cage looks like it could use a redesign, perhaps with carbon fiber reinforcement, to make it stronger with minimal weight penalty.

We'll have to see how the updated "wide range" Sturmey 8 plays out.
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Old 04-29-08, 06:38 PM   #85
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The wide(r) range hub is evidently a slightly modded version of the current one; the step-up ratios are slightly larger but the mech is identical with 3 cascaded planetary systems. The hub appears a little bigger so is likely to be a bit heavier too. The shift adjustment sensitivity has also been addressed.
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Old 05-04-08, 05:52 PM   #86
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I stripped the hub again this weekend, completely washed out all previous lube. The bearings weren't rusted as I thought. I am not sure at all why it was 'crushing rocks'. Perhaps the graphite powder I mixed in with the oil was to blame.

I put in a new product I got last weekend, Rocol cable grease with moly. It goes on very thin, frothing, then thickens up a bit as solvent evaporates, won't run out and the moly eases friction. It feels great now, better than when new I imagine. Used it to commute this morning, all is fine again.

This time for sure?
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Old 05-04-08, 09:36 PM   #87
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Jur,

I had that sound as well, and also as hub felt like it was dragging on something, but when it was dismantled there were no obvious causes, so the bearings were washed and re-greased, the hub put back together and it still made that sound. On closer examination, the plastic disc, (can't remember the proper name for it), that the gear cable hooks into had a tiny groove wore into it from who knows what, maybe a bit of grit, but after another clean, it's all clear..so far as well.
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Old 05-05-08, 07:32 AM   #88
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Well tonight after 1 day of commuting, I imagine it is already not as smooth as before. I am such a bloomin perfectionist. I probably need to back off the left cone a tad.
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