SRAM Automatix 2 speed hub.

[Wildcat]

The SRAM Automatix hub is a 2 speed hub that shifts by itself, you don't kickback or have a shifter. It shifts from low to high at about 10mph. I've used one in city traffic and really like it. It's always in low when you are stopped.
I had the coaster version on my 20" bike I used quite a bit, and I had a freewheel version in the box until I had it laced into a 24" wheel on my latest bike. But I wanted coaster brakes on my 24" wheel, so I opened up both my SRAM Automatix hubs to swap the guts between the two if possible. The coaster brake version and freewheel version use the same hubshell. I've used the coaster version for over a year and only have a couple miles on the freewheel version. I was able to do the swap easily in about an hour, taking my time.
The coaster hub has worked well for the year or so I have ridden with it. The brake is very good and the shifts are always smooth. I wanted to see how it looked inside after being rained on a few times.

To pull the guts, loosen the 2 nuts on the left side. Nothing needs adjusted on the cog side.

The end just slides off the axle and the whole assembly slides out the drive side.

I compared the 2, the coaster looks pretty good for a year's use, compared to the new freewheel one, pictured on the bottom. It uses a plastic insert in place of the brake parts. Plenty of lube in there from the factory.

So, the swap worked, everything interchanged and it was easy, even having never worked on one.

 

[tranimal]

Do you know if I could lace this hub to a vintage Schwinn S2 rim?


Sent from my iPhone using Tapatalk

 

[Wildcat]

It's a standard 36 hole hub, it should lace up.

 

[Bicycle808]

Nice little post, right there. Good to know that the 2 versions are interchangeable, and bood to see the F&S "dna" still intact in this recent design. I'm about to build a bike with the CB version of this hub; i'm pretty stoked about it.

 

[Wildcat]

The best price I found was on Amazon w free shipping. I accidentally ordered the freewheel version, so I bought another one, the CB version.

 

[mornview]

Thank you for the thoughts on this hub; I've been considering it for a long time. I've got a project I'd like to lace up a modern (ie, non-Bendix) 2-speed hub to, so it's basically gotta be either this or Sturmey Archer. I really want the ability to kick shift, but Sturmey Archer's kickbacks seem to get pretty mixed reviews, whereas I've heard nothing but praise on SRAM's hub.

 

[Wildcat]

My favorite hub was a yellow band Bendix until I got accustomed to the auto shift. The auto will stay in high gear until you let off the pedal, so you have a little control over the shifting, but that's it. Also, when coasting, it won't shift back by movement of the pedals, it will stay in the gear the rpm dictates.

 

[Bicycle808]

Yeah, I love kickback hubs, but the more I think about the auto, the more i see the advantages. I think the trick is to gear it properly, and you'll probably love it. I believe the folks who complain about shiftpoints and stuff more than likely have it over- or under-geared for their intended purposes. My plan is to gear it just slightly lower than what I have my singlespeed street cruiser geared at....

 

[Bicycle808]

Plus, of course, these new SRAM 2 speed hubs are supposed to have the best braking action out of any modern-day coaster brake.... I wanna try it before i believe it though....

 

[mornview]

I think my main reservation with this hub has just been it's longevity. I don't entirely know or understand the mechanism that controls the automatic shifting on the Automatix hubs (haven't seen or worked on one yet), but automated parts tend to have shorter lives/are less overhaulable than their manually operated counterparts as a general rule of thumb. And moreover I'm not sure how easy it'd be to get replacement parts for SRAM hubs either.

But I'm probably expecting too much out of a modern product, too; I'd like to be able to build up and continue to use this hub for decades to come, the way some old Bendix and SA hubs are still kickin' around after all these years. Probably not a reasonable expectation on my part .

 

[Wildcat]

Plus, of course, these new SRAM 2 speed hubs are supposed to have the best braking action out of any modern-day coaster brake.... I wanna try it before i believe it though....

I'll vouch for the coaster brake action. As good or better than my old yellow band brakes. I think it's working like the Bendix, off low gear so you get more leverage, and the two brake pads are pretty beefy.
As for gearing, I was tempted to adjust the spring when I had them open, but the shift point works well for me. I added a larger cog so I have a nice low gear to take off with and a high gear that's just a little higher than a normal one speed. My pedals are spinning at about 70 rpm when high gear kicks in.
Brake shoes:

 

[Wildcat]

I think my main reservation with this hub has just been it's longevity. I don't entirely know or understand the mechanism that controls the automatic shifting on the Automatix hubs (haven't seen or worked on one yet), but automated parts tend to have shorter lives/are less overhaulable than their manually operated counterparts as a general rule of thumb. And moreover I'm not sure how easy it'd be to get replacement parts for SRAM hubs either.

The hub works on centrifugal force on 2 arms, in the middle of the hub. They are controlled by a spring which has tension to allow them to open and catch high gear. As you slow and lose centrifugal force they swing back closed. If you unwind the spring, you need more force or speed to engage high gear. I've heard it's not new, that SRAM (Sachs) had this same type of hub years ago. Since the new hub came out just a few years ago, you probably have to get with the factory to get parts.

 

[Bicycle808]

+1 Fichtel and Sachs produced an Automatic hub way back when, mid to late 60s. When SRAM bought out Sachs, they put their name on the company, but acquired the tooling, patents, etc. The new SRAM Automatix is a new rendition of the venerable Torpedo Automatic. More info here: https://hubstripping.wordpress.com/fs-torpedo-automatic/ Keep in mind, the author's primary language isn't English, and this article was written before SRAM (re)introduced the Auto hub, so comments about how centrifugal force clutches haven't been used in IGHs since are no longer accurate.

This hub should be very reliable, and it should last a very long time with proper lubrication and adjustment. But yeah, you're right: parts availability for SRAM IGHs is dismally bad. Sheldon Brown once suggested on his site that anyone buying a new Sachs/SRAM IGH ought to buy 2--- one to lace into the wheel, and the other to cannibalize for parts, if/when things go wrong.
http://sheldonbrown.com/sachs-internal.html#technical (Scroll up for his opinion, obviously no longer current, on SRAM's parts/support for IGHs in the States...)

My plan is to run the hub on a cruiser that probably won't see much mileage, and do my best to keep the hub maintained regularly. If/When it dies, I'll buy another hub if they still sell'm, or I'll just relace the wheel around an AWC or a singlespeed coaster hub. Hopefully, it'll last forever. (I trashpicked a 40 year old "manual" Torpedo Duomatic, and it works perfectly.) But, if it dies in a few years, I'll more'n likely get over it pretty quick.

 

[Bicycle808]

@Wildcat
Can you confirm whether or not the Automatix uses a 10x1mm axle, or a 10.5x26tpi? I've heard that they updated it to a 10x1, but i have my doubts, and the SRAM site doesn't offer much in the way of specs....

 

[Wildcat]

@Wildcat
Can you confirm whether or not the Automatix uses a 10x1mm axle, or a 10.5x26tpi? I've heard that they updated it to a 10x1, but i have my doubts, and the SRAM site doesn't offer much in the way of specs....

They overtorqued the nuts when my tire was changed and stripped them on my coaster hub, so I stole the 2 from the other hub and have looked everywhere for what I'm pretty sure is the size, 10m x 1. The shops here have 1.25 but that's still not the right thread. I'm making a trip to Manila later this month, and I'll hit the big bike shops so I can get my 20" freewheel version going. I got the info on the size here awhile back, so I'm fairly sure that's the size.

 

[Wildcat]

One downside to the hub I noticed, if you hit a good bump in low gear, it will shift up momentarily. But it goes right back into low gear. That's normal, because it uses centrifugal force, the arms move with a certain amount of force.

 

[mornview]

Ah, I knew SRAM had aquired F&S, but I didn't realize this hub was based on an existing design. Now what are the odds they'll revive the Duomatic (especially at the old 112mm spacing)?

One more question - can anyone tell me what the chainline measures on this hub? I'm thinking of using this hub for an upcoming build; just wondering how much screwing around I'll need to do to get it to work.

 

[Tinkerbull]

M 10 X1 is standard tread on older torpedo hubs.

Check out here for nuts
https://www.boltdepot.com/Product-Details.aspx?product=6891

Mopeds like the Puch Maxi has this tread on the flywheel nut and 14 mm hex

 

[Wildcat]

The cog is concave, I flipped it to get a better chain line alignment on this bike, my other bike worked better the opposite way. Is the chain line is measured from the center of the hub to the cog, or from the dropout to the cog? I'll measure it and post up what is is once I find out.

 

[Bicycle808]

M 10 X1 is standard tread on older torpedo hubs.

Check out here for nuts
https://www.boltdepot.com/Product-Details.aspx?product=6891

Mopeds like the Puch Maxi has this tread on the flywheel nut and 14 mm hex

Torpedo Duomatics and Torpedo Automatics, and the three speeds, and most every Fichtel&Sachs or jus' Sachs IGH run 10.5mmx26tpi axles. Not sure about the singlespeed coaster hubs. I got a Torpedo Duomatic and it definitely ain't m10x1. It's 10.5x26tpi, the way Gott intended it.