Problems with Sturmey Archer 8 speed
 

I've built a new wheel with a brand new Sturmey Archer 8 speed hub X-RD8(W).

The first lasted about 100km before losing the bottom 4 gears. The shop replaced it under warranty. The second has only lasted 60km before jamming in 4th, 6th, 7th and 8th. I've now dismantled this hub before returning it and found two small pawls have broken off.

Has anyone else had experience with this hub or am I just unlucky ?

I stripped the hub tonight and have attached some photos. The Sturmey Archer website provides a pdf with an exploded view of the hub. The problem was caused by stripping of some small pawls that lock up various stages of the 3 stage drive. :mad:
Hopefully this is a dodgy batch not a systemic problem.

I have one, I had it for a couple of weeks and it broke... the mfgr. replaced the internals of it free of charge, and so far it's been working fine. I've put a couple hundred miles on it, but I don't beat on it either... the bike it's on is slow. (it's the one in my sig)

My first one [yes, a new (W) ] lost gears. Sturmey appologized profusely, claimed the had a bad batch of piece parts and replaced the hub no charge and no further questions asked. The second one has been OK so far.

There are those that claim there is no way a planetary gear set can be made to withstand 3.25X up-gear, but I don't buy that. Still, these hubs are going to have to start proving themselves.

I've been tossing around the idea of moving my XRD8 to a traditional-frame bike, as on a chopper it's just not geared low enough. My only concern would be if it would hold up to my standing and cranking on it... to clear an intersection, for instance... without breaking. For half the price of a new Shimano, you know it can't be the same quality, but I guess I'm going to have to put it on an upright bike and see.

EDIT: Found this picture of a Sturmey show bike from last year, using the XRD8. Hopefully it would stand up to some abuse.

http://sphotos.ak.fbcdn.net/hphotos-..._4791011_n.jpg

Well, the Sturmey 3-speeds are less than the Shimano 3-speeds, but are beautifully built and have wonderful reputations.

Beyond that, you have to look at the way the hubs are designed. The XR*8(W) is really an innovative design with just three sets of planetaries, no clutch and no sliding elements. The Shimano 8-speeds are much, much more complicated - I'm surprised Shimano can offer the SG-8*31 for as close to the cost of a Sturmey 8 as they do.

Also, I believe the Alfine models are manufactured in Japan rather than in Shimano's IGH factory in Singapore, and that would account for a substanial chunk of the cost delta of those "premium" versions right there. (Sturmey is of course located in Taiwan.)

That's a good point, tcs. It's a very simple design, I just wish they could make it with a better overall gear ratio. I even pondered putting a BMX crank on my mountain bike with a 22T ring. I wonder.... hmmmm.

Did you de-grease the internals before taking those shots, or was it that dry to begin with?

I just recently completed a conversion using a wide ratio 8 speed in a 700c wheel bike. I used the lowest input ratio I could get with Sturmey Archer parts, at 30/25. It's still geared faster than I like, so I may be doing something like you suggest with a BMX crankset.
I did the conversion mostly to run a durability test on the hub with a low input ratio, but the OP's experience is not encouraging.

It's certainly worth looking into, and at less than $150, the hub is cheaper than some nicer single-gear hubs. If you experience any breakage, I would love for you to post about it here, because there's very few people running these on regular-sized wheels that I know of. I also noticed that the left-hand bearing race can get out of adjustment when putting the drum brake back together, which is what I think caused the failure in mine. Make sure the bearing races are snug after the brake is together.

in a 20'' wheel the low gear with a 1:1 [25:24 is close] drive train is .. 19,2"
23:24 .. 20.8"
many have considered it best used as a small wheel hub .

as all the other gears are overdrive ..

It was well greased, I cleaned it with turps so I could get the photos :)

This was built into a 20" wheel with a 44T tooth chainwheel and 25T sprocket. This mean 8th gear is insanely high but all the others are great.

That's encouraging.

Up gearing reduces the torque so should be OK, it's down gearing that increases torque.
I agree, this hub has not got my confidence. On my bike it replaced a 10 year old 7sp Shimano Nexus that kept having problems with the right side cone seal. The Shimano internals looked as good as new.

fastbike;

Thanks for posting the information and photos. There hs been very little information on the SA 8(W) hubs reliability posted so far so your contribution is appreciated. I have posted a link to this thread on the Yahoo geared Hub Bikes group, linked to in my signature block below, for those interested.

The broken pawls look to me like a possibly overhardened parts indicating poor manufacturing process control and QA.

My pleasure. I have had 5 spd SA Sprinter gears on bikes since the early 90's and ridden them quite hard. They've been very reliable. It comes as a complete shock that they cannot maintain manufacturing quality with a new factory in Taiwan.

I've also taken the opportunity to recalculate the gear ratios. The values shown by the factory are rounded to get a nice even 13% step between gears 2 to 7 :) Reality is slightly different.

My actual calcs to 2 dp show:
1=1.00
2=1.30
3=1.48
4=1.68
5=1.93
6=2.19
7=2.49
8=3.24

and the jumps (calculated from the unrounded ratios) are 30.3%, 13.7%, 13.2%, 15.1%, 13.2%, 13.7% and 30.3%.
Aside from the large jump from 7 to 8 this hub has a great set of ratios. If only they could get the build quality up.

I've done some more research. After the first hub failed the bikeshop suggested sending just the hub internals (i.e. axle and gear mechanism) to save weight on postage. I posted the internals off and waited for the replacement.
When it arrived unfortunately it was the 175mm axle unit (my hub has the integrated drum brake and requires the 185mm axle). The bikeshop sent a replacement 185mm unit when I phoned them and told me to keep the 175mm unit (as spares). I've no complaints about the service from the bikeshop (so far).

I've now dismantled the 175mm unit and had a look at the internals. There is a fundamental difference between my "broken" 185mm unit and the "replacement" 175mm unit.

The gear pawls (used to lock the planetary carrier to the ring to achieve unitary drive when the sun gear is unlocked from the axle) are different: on the broken unit the pawl has two teeth which sit over a tooth in the ring gear. The replacement pawl instead has a single tooth which sits in the valley between two adjacent teeth in the ring gear.

So my question is now: given that the design of the pawl has changed, which is the new design - the pawl with the two teeth (the broken part) or the pawl with a single tooth (the replacement part) ?

Look forward to some feedback.

Sunrace Sturmey Archer have come to the party and sent me a new internal mechanism to fit to the existing hub shell :) I did check the design of the sun gear pawls - and they have been changed to have only one tooth.

Hopefully better luck this time. I'll post a progress report in a couple of weeks when I pull the hub apart for an inspection.

On a side note I wonder if they have QA issues as the final drive pawls were binding in their housing. I had to swap this part out from the original hub :)

I've now run about 200km on this hub. After the first 50km I dismantled in to check how it was faring - seemed OK.

I have replaced the grease with a gear oil EP80 which makes it very noisy especially in any ratio using the 1:68 step (i.e. 4th 6th, 7th and 8th). I'm now thinking of dismantling for a clean and regreasing it. The noise makes my city bike sound like an MTB with knobblies in 4th gear :(

I don't think an EP oil is appropriate for this application. That stuff is for hypoid gears as found in truck axles.
I've only got about 100 km on mine, and it's ticking merrily along. It does emit ratcheting sounds from 2nd gear up, but I find the sound to be much softer and less irritating than the Sram iMotion 9 it replaced.
It shifts much more smoothly than the Sram as well.
I will resist the urge to dismantle the hub, as my stated purpose was to do a long term durability test on the hub as delivered with the factory lube.
I don't want to taint any results by unwarranted tampering.
At some point, if it continues to hum along, I will dismantle it to inspect the internals. and of course if it explodes, there will need to be an autopsy.

Good for mountain biking
 

I am interested in an IGH for my MTB. Anybody have any thoughts on the SA XRD8 for mountain biking?

Thanks,

The Sturmey Blog Guy said their hubs were not meant for off road riding.