velomont

I have a winter bike which has been running with a Sachs Super 7 since 1996. It has worked beautifully and maintenance-free until about three years ago. My bike shop admits that they have rarely dealt with internal gear systems from a maintenance point of view but, for the most part, sorted it out though it since performed with a few very minor quirks. This year I brought it out, a few weeks ago, and the first (smallest gear inches) two gears are useless. It feels as though the pawls are failing to engage when pedaling. My winter riding has predominently been in Ottawa with lots of road salt and sand. I have three questions for those experienced with internal hubs:

1. Is this hub finished?
2. If not, is it practicable or even recommended for a reasonably capable amateur mechanic to strip, clean, and rebuild one of these himself? or
3. Should I try a different bike shop?

K6-III

Start by checking the clickbox, as it is responsible for indexing on the S7 hub.

Dan Burkhart 

When you say it feels as though the pawls are not engaging, do you mean it skips intermittently, or there is no engagement at all? Is the anti rotation washer in the non drive side dropout still intact? In early versions of this hub, this washer was quite flimsy and easilly mangled. If this has happened and the axle has turned under pedalling load, the bearing adjustment will be screwed up as a result, and this causes all kinds of internal problems, including engagement failure.
If this is not the issue, you may have internal problems such as a weak or broken spring, broken thrust washer, etc.
Good luck getting replacement parts, as Sram does not import parts for gearhubs to North America.
I have the internals of a Sachs Super 7 on my desk in front of me, useless for want of parts that I am not willing to send to Europe for. It makes a good visual aid for customers who are curious about the inner workings of a gearhub though, so it's not a total loss.

Dan Burkhart 

If you do decide to venture inside the hub, you may find this useful.
https://www.sram.com/_media/pdf/sram/...M_GHS_E_99.pdf

velomont

Thank you for replying, Dan and K6-III. In first and second gears, it will frequently fail to engage for perhaps half or 3/4 of a pedal stroke (possible more) and then engage intermittently. In third and above there is no problem at all. A few years ago, as the problem was first developing (as described in my initial post), I had emailed Sheldon Brown and he suggested a cable and/or clickbox problem.

Two years ago I actually downloaded the SRAM maintenance manual in your link, Dan, which looks rather daunting. Though I've done a lot of my own maintenance previously, including building a bike and building my own wheels, the planetary gear mechanism looks like it could be Pandora's box that I shouldn't meddle with. Would I simply be better off, after eleven years, simply replacing the hub?

Thank you very much.

Dan Burkhart 

Well, it could be a clickbox problem, so I wouldn't throw in the towel just yet. There were two types of shifter/clickbox combos for this hub. There was a thumb shifter which was paired with a non adjustable clickbox, or a rotary shifter with a mini clickbox. If you have the mini clickbox, it can be adjusted as per instructions on page 38 of the manual I posted the link to earlier. If you have ruled that out, along with bearing adjustments, and if you have no reliable means of having it repaired, it might be time to think about upgrading to Shimano Nexus or Alfine. The red band Nexus 8 is about the same price as the Sram S7, and a much better choice in my opinion. You did not mention what type of brake you are using, but if is coaster or drum brake, you could get a Nexus 8 with coaster, although not in the red band version, or a red band with a roller brake. If you are using rim brakes, I'd reccommend the Alfine. (I'm assuming your bike is not set up for discs, if it is, even better.) Believe it or not, the Alfine is a little cheaper than the red band Nexus.
I finally got my first shipment of aftermarket Alfine hubs and shifters, but I'm still waiting for the fitting kits which are backordered from Shimano.
Dealing in aftermarket gearhubs can be frustrating on this side of the Atlantic, let me tell ya.

rwahmad

Dear Guys,
I have also some problem in Sram/sachs S7 gear hub, I hope if anybody can guide me.. Actually, I forgot to tight coaster break nut and it during riding disappread and hub itself opened apart and stucked. Later on I repaired it with the help of helper at students' cycle workshop at Uni, but now 4,5,6 and 7 gears are working but 3,2,1 gears do not work or became difficult as 5,6 or 7. There is nothing missing or broken inside. Just bigger boll carrier was a bit de-shapped and with hand push again was good in shap and fit.
Can someone guide me? further how important is or not mounting tool to use on planetary gear carrier?
any guidance would greatly appriciated.
Regards,
Waqar,
Germany