Author Topic: Gears in a can that don't suck  (Read 835 times)

quixoticgeek

  • Mostly Harmless
Gears in a can that don't suck
« on: July 28, 2020, 12:01:47 pm »

My experience of gears in a can is a bit limited, I've used SA 3 speeds, which are okish, in so far as all 3 gears are usable, but of course lacking in range. I've got a SA8 speed on the Brompton, it's ok, but 4th gear is rough as hell, to the point of being unusable, gear 6 is also rough, but is at least usable.

Is there a ~7/8 speed IGH that is affordable, but where all the gears are usable and smooth? A friend wants to replace the 3 speed SA on their bike with something that works when there's hills...

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

LittleWheelsandBig

  • Whimsy Rider
Re: Gears in a can that don't suck
« Reply #1 on: July 28, 2020, 12:09:15 pm »
Shimano Alfine 8 works well, even in MTB service. Smooth running and shifting is a Shimano trademark, even though the Alfine drag is greater than you might expect.
https://www.bikester.co.uk/shimano-alfine-sg-s7001-8-hub-8-speed-disc-center-lock-silver-517432.html

https://www.cyclingabout.com/speed-difference-testing-gearbox-systems/ compares various non-derailleur gearing systems but does not include the Shimano Alfine 8, which has somewhat lower drag than the Shimano Nexus Inter-8
Wheel meet again, don't know where, don't know when...

Re: Gears in a can that don't suck
« Reply #2 on: July 28, 2020, 12:30:18 pm »
Yes, Alfine 8, though I would say that...
https://yacf.co.uk/forum/index.php?topic=116330.0

Auntie Helen

  • 6 Wheels in Germany
Re: Gears in a can that don't suck
« Reply #3 on: July 28, 2020, 12:32:43 pm »
I like my Alfine 11 but perhaps more than is needed for the use case.
My blog on cycling in Germany and eating German cake – http://www.auntiehelen.co.uk


Re: Gears in a can that don't suck
« Reply #4 on: July 28, 2020, 12:46:06 pm »
I like the Alfine 11 but my Moulton TSR came with an 8 and I'm not finding any great disadvantage now I have made the bottom gear low enough for what I want.
Never knowingly under caffeinated

Kim

  • Timelord
Re: Gears in a can that don't suck
« Reply #5 on: July 28, 2020, 12:52:15 pm »
In my limited experience, the Alfine 8 is *much* smoother than the XRF-8.
Careful, Kim. Your sarcasm's showing...

Re: Gears in a can that don't suck
« Reply #6 on: July 28, 2020, 03:39:14 pm »
I'll put in a good word for Nexus 7; not super-efficient on paper, but feels nice to use because it shifts well, with nicer gear intervals than Nexus8/Alfine 8, and pawl drive rather than mushy feeling roller clutch drive.

Nexus 8 'red band' models have roller bearings on the planet pinions, like Alfine 8, so have the same gear ratios and are comparably efficient. 

SA 5s hubs have a wider range than 3s hubs but are a lot of trouble for a slightly wider range.

Apols if this is obvious but if you fit a larger sprocket to SA 3s, so that the high gear becomes 'normal' this makes first gear into a reasonable gear for climbing. This is an inexpensive way of avoiding the issue.

cheers

Re: Gears in a can that don't suck
« Reply #7 on: July 28, 2020, 05:15:40 pm »
I'll put in a good word for Nexus 7; not super-efficient on paper, but feels nice to use because it shifts well, with nicer gear intervals than Nexus8/Alfine 8, and pawl drive rather than mushy feeling roller clutch drive.

Nexus 8 'red band' models have roller bearings on the planet pinions, like Alfine 8, so have the same gear ratios and are comparably efficient. 

SA 5s hubs have a wider range than 3s hubs but are a lot of trouble for a slightly wider range.

Apols if this is obvious but if you fit a larger sprocket to SA 3s, so that the high gear becomes 'normal' this makes first gear into a reasonable gear for climbing. This is an inexpensive way of avoiding the issue.

cheers

I didn't know you can still find Nexus 7 hubs for sale. I have SA3, SA5 and Alfine8. Of all these the obvious one on paper is the Alfine and with 2:1 ratios (44/22, 38/16 etc) you are fairly well placed for most normal use, a bit short on the top end perhaps but low enough for most uses. I don't entirely trust mine but that's because it only cost me 30€ and I don't know its past history. Gearing is acceptably close, except at the ends (where  it doesn't matter so much). (I think I'm on 32/17 at present but it might be a 16).

My SRF5 W is quite nice to use in a different sort of way, but fussy, fiddly and, I would guess fragile. I need my reading glasses every time I need to take the wheel out because it never seems to go back in quite the same way and I can only see the yellow dot with close glasses. 44/21 or 22, I would need to look to be sure. It's on a steel 80's race frame for a bit of fun but I don't use it as much as I should.

The AW is on a "vintage"style bitza and runs 46/24 which gives gearing for getting up Limousin hills. Reliable relaxing ride and doesn't need anything over the 67"top (I think that's what it is, about 5.4m in post Brexit currency - although I had to look that one up, it doesn't mean anything to me  ::-) ) The old style Sturmey trigger just below the brake lever is also a much nicer thing to use than the SRF5's ratchet that I have mounted on the stem (lhs means that the lever can't go into sensitive body parts during crash stops). The Alfine has now been fitted with a twistgrip (on flat bars) which I find easier than the rapidfire trigger with my arthritic thumb. The 5 is going to get a barend shifter.
 Of all three the one that does most work and that I definitely would not want to lose is the Alfine.

Edit Late idea. If your friend is already running a SA 3sp, have they considered simply putting a second sprocket on to get some lower gears? Something like 18-21 (the sprocket combination used by the Sachs 2x3 Torpedo, although others are possible) works quite nicely. Three tooth differences seem to split the gaps; I have not tried working out the bigger sprocket differences.

Re: Gears in a can that don't suck
« Reply #8 on: July 29, 2020, 01:23:50 pm »

I didn't know you can still find Nexus 7 hubs for sale.

yep. They redesigned it a few years ago so that the way the axle works to lock the sun pinions is similar to the Nexus8 now, i.e. pawls in the axle rather than pawls hidden inside each sun.

Despite the redesign they have (I think) retained the Nexus 7's killer advantage, being that every single Nexus 7 hub internal (non coaster type) will swap into every single N7 hubshell, going back at least 25 years.  You can't say that about nexus 8....

Also shimano now make a Nexus 5 hub; this is, internally, pretty much a hamstrung Nexus 7, but ought to be no worse, and in flat territories, the 5 gears ought to be enough.

cheers

nicknack

  • Hornblower
Re: Gears in a can that don't suck
« Reply #9 on: July 29, 2020, 03:26:56 pm »
I've had a Nexus 8 for the last 10 years or so. It's been completely trouble free.
There's no vibrations, but wait.

Re: Gears in a can that don't suck
« Reply #10 on: July 29, 2020, 04:10:06 pm »
BTW all hub gears need maintenance.  For example here is  Nexus/Alfine 8s hub which has not been maintained;



cheers

Re: Gears in a can that don't suck
« Reply #11 on: July 29, 2020, 06:49:59 pm »
BTW all hub gears need maintenance.  For example here is  Nexus/Alfine 8s hub which has not been maintained;



cheers
Was it repairable?
Never knowingly under caffeinated

quixoticgeek

  • Mostly Harmless
Re: Gears in a can that don't suck
« Reply #12 on: July 29, 2020, 07:51:58 pm »
BTW all hub gears need maintenance.

Someone should tell the Dutch that...

Quote
For example here is  Nexus/Alfine 8s hub which has not been maintained;



cheers

Blimey, that looks ugly. Seal failure? Did you manage to resurrect it?

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Re: Gears in a can that don't suck
« Reply #13 on: July 29, 2020, 10:19:51 pm »
not my photo but I've seen plenty similar.

They can look as bad as that mere weeks after water gets in, seemingly because shimano think it is OK to use grease in their IGHs which is notable for its lack of corrosion inhibitors.

If you catch it early enough it is usually possible to save the hub.  But if it looks like this for more than a couple of months there is likely to be more extensive damage. Hubs that are so bad they have to be scrapped are commonplace. Often the ring bearing fails first, which tells you where the water is probably getting in.

I have seen hubs which were badly greased in the factory and the water got in, such that much of the grease still looked clean, but the ring bearing was worn out (via a corrosion-erosion mechanism) and the roller bearings on the planet pinions were seized solid and had to be, uh, 'percussively maintained'......

cheers

Re: Gears in a can that don't suck
« Reply #14 on: July 29, 2020, 10:32:45 pm »
I'll put in a good word for Nexus 7

That’s what I have on the e-bike. Can’t fault it, although I rarely stray out of 4th and 5th. Shifting is good with only the occasional “hang”, usually because I haven’t briefly eased off at quite the right moment. Wheel removal is easy enough too.

Re: Gears in a can that don't suck
« Reply #15 on: July 29, 2020, 10:53:45 pm »
FWIW you can see the difference between N8 and N7 gearing here

http://ritzelrechner.de/?GR=SNI8&KB=38&RZ=18&UF=2185&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=SNI7&KB2=38&RZ2=18&UF2=2185

N8 has one much lower gear but also has wider gaps (18%, 22%) in the midrange, and less uniform intervals overall (14% to 22%), where N7 has closer and more uniformly spaced (17%, 14%, 17%, 16%, 17%, 16%)  intervals .

N8 premium and A8 use more efficient roller bearings in the planet gears (good) but also use roller clutches (bad, for some folk). So N8 premium and A8 ought to be more efficient for smooth pedallers but N7 might still feel nicer to ride on.

there are two N5 models but the most recent (I think) appears to be comparable to N7 apart from

-N7's gear 1 and gear 3 are missing and
- N5 uses a direct drive gear in second where the same ratio (near enough) in N7 (4th gear) does not use direct drive.

This version of N5 has intervals of 33%, 16%, 15%, 16%. Compared with N7 here

http://ritzelrechner.de/?GR=SNI5&KB=38&RZ=18&UF=2185&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=SNI7&KB2=38&RZ2=18&UF2=2185

cheers

Re: Gears in a can that don't suck
« Reply #16 on: August 02, 2020, 10:55:10 am »
I've been running an SA-8Sp X-RD8 for 5 years or so and 4500 miles. I too had a crunchy sounding 4th, although 6th was fine. At 4000 miles the LBS were asked to maintain it, and for the remarkably low sum of £80-odd just replaced the internal assembly since they couldn't sort the crunchiness.

Since then it's run-in nicely and now going excellently. It's comfortably the cheapest IGH for 315%, and I suspect that the unwanted noises were a function of water getting in unnoticed and doing some damage; or maybe just poor initial assembly. Anyway, I'll put in a good word for it 'cos no one else will.
Cruzbike V2k

quixoticgeek

  • Mostly Harmless
Re: Gears in a can that don't suck
« Reply #17 on: Yesterday at 10:26:46 am »


Does the alfine 8 require any special tools to open up and service? Anything inside that shouldn't be coated in grease?

J
--
Beer, bikes, and backpacking
http://b.42q.eu/

Tim Hall

  • I want to eat the fleeting shade of your lashes
Re: Gears in a can that don't suck
« Reply #18 on: Yesterday at 10:31:05 am »


Does the alfine 8 require any special tools to open up and service? Anything inside that shouldn't be coated in grease?

J
No special tools that I recall. There's a pingfuckit circlip that needs to be prised off (and then retrieved from the depths of the garage if it escapes). When I was I/C maintaining an Alfine 8 speed I didn't grease anything but dunked it periodically in automatic transmission/power steering fluid.
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)

Re: Gears in a can that don't suck
« Reply #19 on: Yesterday at 12:00:10 pm »
It is not difficult to add a lube port to N7 or N8 (eg using the cap from A11); it just requires a drilled and tapped hole.

The hub can then be run in oil (eg. added to the grease that is already there). This concoction doesn't inherently resist corrosion much better than the original grease does (and nor does ATF BTW) but much as with IGHs of old, if there is something coming out, there is unlikely to be water getting in either, so if there is enough lube inside to make a bit of a mess externally, the hub is probably OK inside.

In the long term cleaning the internal and running the hub in a better specified SFG (with more corrosion inhibitors etc) is much the best plan.  In theory if the SFG has solid lubricants in it, it might interfere with the operation of the roller clutches. In practice this doesn't seem to happen.  If you want to buy something off the shelf  that will do the job, the type of SFG which is specified for use in Land Rover front swivel joints is pretty good; it resists wear very well, and is chocca with corrosion inhibitors.

cheers