Stu In Tokyo

I've been using my Charge Mixer 8 for just about a year now towing a trailer full of goods around on my deliveries here in Tokyo. Sometimes the weight of the trailer and product gets up there, 125Kg+ range. I have geared the bike down a bit, it came with a 39T front chain ring and an 18T cog, I went for a 23t cog. This was great, but I recently went from 700C wheels to 26" so I could run fatter tyres, the Mixer's frame is quite tight on the rear for tyre clearance. So I changed the rear cog to a 22T unit.
Recently I've had a lot of missed shifts and a few times where the crank just slipped a half rotation in an instant. I have about 3000Km on the bike, I use it most days, six to seven days a week, 95% of the time hauling a trailer full of product, we run a liquor shop.

Here are the six shafts from the Carrier Unit, these shafts hold the six planetary gears in the cage. They have needle bearings, but the shafts are in bad shape.

When I took the hub apart to clean it and do an oil bath, the entire guts of the hub were covered in metal shavings, or flakes.


Shimano does NOT sell parts for the carrier unit, (part #4) you have to buy the whole thing, which is going to cost me 10,400 yen or $135 bucks.


Yep that is a lot of parts, but I got it all back together as I need the bike for work, I hope the new part will get here this week, then I'll swap out the carrier units, I'll then go looking for a machinist who can make me six new shafts out of better quality metal, and I'll be doing an oil bath for the hub every few months.
Over all, for my application, which I admit might be extreme I'm not very impressed.
Maybe a Rohloff is in my future....?

My rig loaded.....

BlazingPedals

I ran a Sachs 3x7 (now SRAM) for years on one of my recumbents. Probably close to 20,000 miles trouble-free. It gave me a gear range of 17-144 inches. I finally took it off when I decided I didn't need that kind of range and returned the bike to 'stock' gearing. It's a slower machine, now, without that big gear. If I decided that I needed that kind of extended range again, I wouldn't hesitate to get a new SRAM Dual-Drive. I hear that Sturmey-Archer also has a similar hub, but I've never seen one.

wahoonc

Interesting. I am well aware of the lack of parts for Shimano hubs, one reason I am hesitant to use them.

In your case I wonder if converting the hub to oil bath might be a good idea. Drill a hole in the shell and add an oil cap, similar to the Sturmey Archer. I also wonder if you might be better served by one of the older style NuVinci hubs. I have seen a few of those being used for cargo duty with electric drive.

Aaron

OndrejP_SK

One of the earlier posts in this thread has made me wonder whether there should be a minimum recommended chainring:sprocket ratio depending on wheel size... or maybe minimum recommended gear-inches ?

With the same ratio if I use 20'' wheel on a folding bike, I travel distance X per revolution of cranks, if I use 28'' wheel I travel a longer distance. Simply from a layman's point, the hub is subject to more stress with a larger wheel...

Monster Pete

A recommended chainring/sprocket ratio makes the most sense. Changing the wheel size with the same ratio will affect the overall gear, with the result that you can have a lower gear with a smaller wheel without overloading the hub. For the same overall gear, the hub is under more torque with a larger wheel. That said, I've never found an official recommendation for SA 3-speed hubs to back up the 2:1 'rule' that keeps popping up. Indeed, you can get 3-speed hubs with splines for a cassette, indicating that you can run them with quite low gears without damage.

DCB0

No. The maximum stress on the hub will be when the wheel is blocked or jammed and the rider puts full force into the pedal, and this force is the same regardless of wheel size. Like Monster Pete says, the gear ratio alone is all that needs to be considered.

fietsbob

if there is a set of compound reduction gears inside the hub,
then there is less stress on the gearing with a bigger external ratio..
rohloff has a second reduction gear with low range further reduction of
#8+
so a 16/53 in a 20" wheel. is better than a 16/38 with a 26" wheel,
but the hub laces into the bigger hub so much nicer,
they did really make the thing for Mountain bikes , initially.

tandem they specify a bigger chainring.. in the owners manual..

no1mad 

Pardon the intrusion, but if a bike has a given o.l.d. of 120mm, does that mean any hub with less than that work? Or there other variables to consider?

DCB0

Ideally you want the OLD to match the spacing in the frame... if you have 120mm spacing in your frame you should find a hub with 120mm OLD. If the OLD is off by 5 or 6 mm (bigger or smaller), you can usually just squeeze it into place. Any larger than that should only be attempted with a steel frame which should probably be 'cold set' to match the OLD.

no1mad 

That clears things up a bit, thanks.

MichaelW

I think metal shavings are the result of initial break in period. Grease doesnt really remove it very well. I left my grease in for 2 years before converting to oil so if my Alfine may be worn like that thre is little to be done. I checked my oil after 6 months and found there was plenty sloshing around inside so I'm happy with an annual bath.

If you replace the worn shafts with harder material, take care that you do not wear down the planetary gears rather than the shaft.

fietsbob

may add spacers to the axle , but you may run out of thread,
to screw the outer nut on.

FWIW, all parts of Sturmey AW3 hubs are available ..

the galling on those planetary axis pins is ugly
the grease may not have penetrated well enough
to lubricate them adequately.
particularly in the cold months..
hauling 275 pounds may also be part of the problem.

perhaps the trailer needs a couple electric booster motor hubs.

OndrejP_SK

I'll add my experience with IGH.

1) Nexus 7 (7C21)
- Bought it used, just to try the concept. The hub had pitted bearing races, the cages have scarred the balls and the distorted balls damaged the bearing races.
- Really poor sealing on this hub.
- The efficiency is miserable, but I suspect that this is partly due to the bearing races + the coaster brake.
- There is no direct gear and all gears use 2 stages of planetary gears to adjust the ratio.
- What I liked about this hub is the jumps between gears. I would really love to try one of the last 7 speed models for roller brake (7R50).

2) Nexus 8 red band "premium" (8R36)
- bought new for 160€
- much much much better efficiency. I hardly feel any drag at all compared to the 7speed.
- not so even gear jumps (there is a huge 22% gap between gear 5 and 6 where I use it the most)
- different shifter which occupies more space on the handlebars

BTW I use it with drop bars mounted on the stem like Sheldon Brown:


And I'm looking forward to trying out the Alfine 11.

Micheal Blue

Recently I got an 8-speed Nexus hub for my Surly LHT. 38t chain ring, 21t sprocket.
Comes to about 24 gear-inches at the low end. That's about 7 or 8 km/h to about 27 km/h speed range. It works very well. I use it for commuting @ 40 km return trip. I also had it out of the city for a country ride in a (steep) hilly area. Worked great.
As mentioned in another post, Heins Stucke (sorry if I don't spell his name correctly) toured around the world on a BF Pocket Llama with a 7-speed Nexus hub. Fully loaded bike to all kinds of terrain. Shimano doesn't recommend lower ration than 1.9 or 2. So my gearing is right at that mark. The 11-speed Alfine adds gears on top, but nothing on the bottom, so for hill climbing it's as useful as the 8 or 7-speed hubs. Gearing-wise, the Alfine is for racers, not for tourers. I wish the Shimano engineers would make a hub for tourers.