Thorn Cycles Forum
Community => Rohloff Internal Hub Gears => Topic started by: Andre Jute on July 11, 2010, 10:15:26 PM
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We speak often of what fabulous engineering the Rohloff gearbox is. The point of modern engineering is interchangeability. Yet we have a good deal of correspondence on how Rohloffs differ in, for instance, the noise in various gears. And there is the infamous one per cent that requires adjustment at the factory. On the other hand, Rohloff gearboxes, once they work, have a reputation of working forever with minimal maintenance, and to be hardy even in the presence of neglect.
The Rohloff punctilio thus appears to be more the kind practised by artisan fitters and turners, giving each gearbox a slightly different character. Nothing wrong with that, of course; people pay extra for that sort of special craftsmanship; my Bentleys were none the worse for being substantially handmade (and I'm on record as saying that any modern Dagenham Ford is damned good car, because it is). Sorry for the car analogy, but it is what made even a short journey in a Bentley an occasion whereas the Porsche I drove for many years as a young man were (after the 356) merely tools of transport. A ride on a Rohloff-equipped bike is similarly an occasion and likely to remain so forever whereas a ride on the best Shimano Nexus (the fully-auto Di2 Cyber Nexus (1)) soon became just exercise.
It would be interesting to hear from those with two or more Rohloffs in the family, or those who got a second Rohloff in quick succession to the first one, if they notice differences in character.
Andre Jute
(1) Description of Di2 Cyber Nexus autobox and electronic adaptive suspension at:
http://www.audio-talk.co.uk/fiultra/BICYCLE%20%26%20CYCLING.html
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Andre,
I just got my second Rohloff (the first one was stolen :-[)
This one (internal) is smoother to change all gears, the first one (ex box)was sometimes a bit notchy changing up into 3, 5 and 10, 12 and the 7/8 change up had to be smooth and slow to avoid an interim kick into 14.
I prefer my second one so far!
Julian.
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This one (internal) is smoother to change all gears, the first one (ex box)was sometimes a bit notchy
This is what I mean. The collective wisdom on the trail is that the EX box is smoother-shifting. But here you go, preferring a new internal box to a presumably well-run-in external box. There might of course also be an element that Rohloff, with a 100,000 gearboxes under their belt (extraordinary if you consider the elevated price) is simply building a more consistent/smoother box. -- Andre
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My Rohloff didn't seem to be behaving properly, so I sent the wheel back. It came back with Rohloff saying there was nothing wrong (excellent service from SJSC, by the way). It seemed the same as before.
One issue was that, especially after I had recently changed from 8 to 9, there would be a click, as if the gear had changed, but it seemed not to have.
Another is that at times the gear seems to "catch" and throws my feet off the pedals. I do try to ease off or to ensure I change with the cranks vertical.
Any comment, anyone?
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Pyjamas,
How many miles has your hub done and when was the oil changed last.
My first hub improved noticeably with a couple of oil changes early on and continued to get smoother with a few thousand more miles. It was stolen at 4000+ miles, so I doubt I will find out how much better that particular hub gets with more mileage ;)
Julian.
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My Rohloff didn't seem to be behaving properly, so I sent the wheel back. It came back with Rohloff saying there was nothing wrong (excellent service from SJSC, by the way). It seemed the same as before.
One issue was that, especially after I had recently changed from 8 to 9, there would be a click, as if the gear had changed, but it seemed not to have.
Another is that at times the gear seems to "catch" and throws my feet off the pedals. I do try to ease off or to ensure I change with the cranks vertical.
Any comment, anyone?
Wild guess, but could the cables be too tight?
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Julk, I sent it back at 2,500 miles and the oil was changed then. I changed it again at 5,500 miles.
Geocycle, I don't think so! But I'll have a look.
Anyway, thanks both.
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Pyjamas, my Rohloff developed a nasty kickback in 3rd gear and phantom changes around gears 5 or 6. The 3rd gear kicks would have thrown my feet from the pedals but for the strapless toeclips. Problem was solved by removing the rear wheel and whacking the axle a couple of times with the sole of a shoe (the Rohloff approved solution involves a rubber mallet but I had no idea what the Thai word for rubber mallet was nor how to mime 'rubber mallet' to a Thai hill tribe so the shoe would have to do). The problem developed 11,000km into a tour and the hub was about 1,000km overdue for an oil change. Is running fine now and will gets its even more overdue oil change when I get home next week.
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The Rohloff punctilio thus appears to be more the kind practised by artisan fitters and turners, giving each gearbox a slightly different character....
It would be interesting to hear from those with two or more Rohloffs in the family, or those who got a second Rohloff in quick succession to the first one, if they notice differences in character.
Andre Jute
My wife and I both have bikes fitted with Rohloff hubs. I think that subtle differences in performance between individual hubs is less indicative of a romantic notion of craftsmanship. Rather, it is symptomatic of tight tolerance engineering design. Variances in these tolerances, even small ones, are more significant than they would be in a car gearbox which is larger and heavier with less gears. This results in subtle variations in running efficiency and often noise.
I have yet to read a satisfying explanation of why gear 7 is the noisiest. Gear 3 and 5 should be in theory as they utilise all three planetary gearsets, whereas gear 7 uses only 2.
The two Rohloffs I purchased are similar serial numbers. Yet my wife's tends to be quieter freewheeling and running than mine.
Mine had to be returned to Rohloff because of gear slippage in gears 1-7. The verdict was that a small quantity of Loctite had penetrated into the reduction gearset. Given I had only performed oil changes up to that point I'm not clear where the loctite came from. Possibly fitted originally by the factory when assembling the Ex box plate?
Cheers,
Tony
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The two Rohloffs I purchased are similar serial numbers. Yet my wife's tends to be quieter freewheeling and running than mine.
Mine freewheels a lot quieter in gears 1-7 than 8-14 which is quite noisy, opposite to noise levels when pedalling, is this normal?
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It probably is. I've noticed at least quite a variation in freewheel noise from gear to gear.
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Mine had to be returned to Rohloff because of gear slippage in gears 1-7. The verdict was that a small quantity of Loctite had penetrated into the reduction gearset. Given I had only performed oil changes up to that point I'm not clear where the loctite came from. Possibly fitted originally by the factory when assembling the Ex box plate?
The grub screw that closes the oil hole in the hub has Loctite on it from new, and the grub screws that come in service packs of oil and syringe also have Loctite already on them. So, every time you perform an oil change, there is a chance for some Loctite to fall into the hub. I'm amazed to hear that it has the effect of stranding your bike while the hub is sent to Germany.
Andre Jute
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The grub screw that closes the oil hole in the hub has Loctite on it from new, and the grub screws that come in service packs of oil and syringe also have Loctite already on them. So, every time you perform an oil change, there is a chance for some Loctite to fall into the hub. I'm amazed to hear that it has the effect of stranding your bike while the hub is sent to Germany.
Andre Jute
Actually, I was returning to Australia anyway, so had to pack up the wheel from Perth (when I got home) and send it to the service centre in Brisbane.
They stripped the thing down and that was the only conclusion they came to. It is certainly fine now.
However, two year on it still leaves me a little perplexed and wondering, if it was Loctite (as Maria from Rohloff suggested), whether it has happened to anyone else, and whether it will happen again...
Cheers
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I have seen advice in an old post to use a new grub screw at each oil change, but if you reuse the old grub screw with new loctite to let the loctite dry before inserting the grub screw.
This to avoid the chance of liquid loctite entering the hub.
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I have seen advice in an old post to use a new grub screw at each oil change, but if you reuse the old grub screw with new loctite to let the loctite dry before inserting the grub screw.
I remember seeing that too.
I was wondering the other day whether the Loctite on the grub screw has a sealing as well as a locking function. Earlier, as reported elsewhere on this board, after finding pools of oil under my bike and hearing squeals of protest every time the brakes touched the rims, I drained the Rohloff's oil, after consultation with the experts here found it enough and, since it was clean from a recent full service, just put it back in, reusing the grub screw. Some weeks later I noticed that oil was leaking onto the hub from the grub screw, smears rather than pools, but still enough to have my attention drawn to it in the first instance by noisy brakes caused by a few drops on the rims. On removal the grub screw proved to be utterly bare of any Loctite. I wiped the screw thread in the hub with a cotton earbud and inserted a new Loctited grub screw that I had in stock as a spare (I bought a handful of Herr Rohloff's grub screws with the bike on hand of experience losing hard-to-find -- eventually found them at Petra Cycles -- rubber grease hole bungs from Shimano roller brakes, which then flung their grease out and next locked solid at 50kph just as I was coming up to a sharp turn with gravel on it -- fortunately it was the rear that locked up but now I'm sensitive to small buy but crucial parts that can fall off!). The oil leak stopped. Hence the thought that the Loctite maybe seals as well.
Andre Jute
http://www.audio-talk.co.uk/fiultra/Andre%20Jute's%20Utopia%20Kranich.pdf
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Wow, getting kicked by the pedals does not sound fun. Sorry to hear about the folks who have had problems with this. However, I am very encouraged to hear that should I ever run into this problem, it can potentially be solved with a shoe! Luckily I carry 2 on every ride. The thought of sending a wheel to Germany from the states has always sounded like a real headache.
Fortunately for me, my hub has been nothing but stellar. And as others have mentioned, it certainly does have personality. My freewheel noise changes pitch and speed with the seasons, with the level of oil and with whatever neutral routing my hub chooses at the moment (from what I understand, this can be a few different paths, depending on what gear you are in). Sometimes while maintaining a coasting speed, my freewheel noise will audibly shift as the hub decides on an easier neutral output.
Besides that, just the standard whirring noise while pedaling in gears 6 and especially 7. I love the noise because it reminds me of the mechanics happening inside.
By the way, I'll take a stab at the 6th and 7th gear noise:
-First, let’s set the stage. Imagine standing behind the bike, looking at the hub. Drive sprocket on the right.
-I theorize that it is a misalignment of the spur gear teeth where the twin planet carrier meshes/ouputs to ring gear 2.
-I think the twin planet carrier has a touch of slop (not the assembly itself, but how much space is allowed between its planets, and the ring/sun gears that they mesh with), which is good for manufacturability, and also raising efficiency. If you think about it, it MUST have slop, since it interfaces with so many other gears. When I think of the twin planet carrier, I think of it “floating” in between the 4 sun gears inside and the 2 ring gears outside. I have seen a picture of this assembly and the planet-to-sun gear mesh does look a bit loose.
-So, while in gear 6 or 7, ring gear 1 is locked to the right side of the twin planet carrier and also to the first two sun gears.
-Now the left side planets walk within ring gear 2, but perhaps it is being leveraged by the firmly-held right side of the twin planet carrier, ring gear 1 and the first 2 sun gears?
-Basically all the tolerance or slop is being forced to the left side and it causes the left side of the twin planet carrier to misalign or torque (slightly) with the interior of ring gear 2.
-Spur gears are noisy by nature with their large contact faces, but a touch of misalignment during the meshing really turns up the noise.
-So now imagine all three planet gears on the left side of the twin planet carrier, being slightly tilted as they walk around the inside of ring gear 2.
-Does this also explain why most efficiency tests rate 6 and 7 as the least efficient gears?
-Gear 6 rates slightly better, and I imagine this is because only 2 gears are mating (planet and sun gear). Gear 7 is worse, because now 3 gears are mating (planet, sun and ring)
-So why only 6 and 7?
-In gears 1 and 2, the left side of the twin planet carrier is locked, and the right side (ring gear 1) is walking the planets. Seems like it would perform just as noisily as gears 6 and 7, however ring gear 1 is very close to three sets of supporting bearings and closest to the input drive (sprocket), so I envision less flex or tilting happening on this end.
-In gear 4, the twin planet carrier is locked on both sides, so there is no gear meshing happening anyway.
-In gears 3 and 5, the planets are being walked in both ring gears 1 and 2, which seems like a balanced distribution of force on the twin planet carrier.
-So, since gears 6-7 and 13-14 are essentially the same, why are only 6 and 7 noisy?
-I don’t know. Maybe 13 and 14 are as noisy, but at those speeds and the difference in typical cadence, it just isn’t as easy to hear.
-Or, maybe the locking of planet set 3 in gears 13-14 helps balance the load of the twin planet carrier between ring gear 1 and ring gear 3?
-Lastly, I wonder if the interface (possible slop) between ring gear 3, planet carrier 2 and sun gear 3 are behind all of this. No, that cant be, because in theory all gears 1-7 would be noisy if that were the case.
-And last but not least, maybe I am totally off point, and the whole thing is just an acoustic phenomenon.
Looking forward to hearing others thoughts,
Beave