imabeliever1

Planning on ordering the S/A 2 speed hub. My thoughts on setup were use a cog that puts the "high gear" in a comfortable range for me and local terrain. So, when I shift down (direct 1 to 1) I have an lower gear to get over a long hill or to use when tired.

Anyone here currently use or have some past experience with a kickback on a roadbike and what was your setup ????

Thanks for your time

SirMike1983 

It depends on the terrain and your riding style. Most of the kickbacks I've worked with are Bendix types from the 1960s. The basic principle is the same though as to setting your gearing up. If you're going to be going up anything more than very mild climbs, then I'd go with a larger rear cog with a normal-high hub. This is especially true if you're going to be coasting downhill. If you're just on flat terrain or you want to be able to "push" downhill too, then normal-high stock is often pretty good. The idea is just what you said-- pull the high down and make the normal a "climber". Bendix addressed this concern by making a couple different kickback hubs: "normal-high" and "low-normal". The user at home can tweak using the cog size as needed.

nlerner

The specs show the new SC2 as having gear 1 = direct drive and gear 2 = 138% of direct drive. So for all-purpose riding (i.e., no serious hill climbing or descending and assuming a 700c wheel), I'd get the direct drive gear around 55", which will give you a "high" gear of 76"; you can do that with a 45t crank ring and a 22t rear cog. Or gear it a bit lower so that the direct-drive is your hill climbing gear at around 48" and then you'll have a high/regular-riding gear of 66". You can do that with a 40/22 combo.

Neal

noglider 

And let us know how it goes once you have it going!

LWaB

I used a Sachs Duomatic 2sp hub for the 2003 Paris-Brest-Paris, top gear was around 70", bottom gear about 53". It worked well with no dramas.

BruceMetras

This is a bike project that I completed a few months ago .... I set it up for approximately 55/75 gear inches.. I ride this bike quite a bit in moderately hilly Marin county .. the ratio works out about perfect for me allowing cruising speeds in the 16 to 20 mph range.

Old Douglas Titanium road frame.



Sort of rare Sachs Duomatic 2 speed Automatic hub from 40 years ago modified to shift at 14mph at a cadence of approximately 90rpm.



Forward Components EBB kit in stock 68mm BB for chain tension adjustments.

Rocketcycles

Bruce,
That is a nice ride. I'm envious!
I would like to build a similar ride some day.
For now, I'm finishing a single speed 700c coaster with a Torpedo hub.
I'm in the market for a Duomatic though.

Did you build up the rear wheel yourself?

Regards,
Randy

imabeliever1

Got my hub on Thursday. The bearings were set very tight, but a little adjustment makes everything fine. Will get some spoke washers this week to begin lacing the wheels. With the parts I have on hand, 21t cog and a 38t chainring , it should be about 48/68 gear inches running 27" tires. I am looking forward to getting everything together and giving it a run.

Grand Bois

You think it needs spoke washers? I use them on steel SA hubs, but the new aluminum-shelled hubs have pretty thick flanges.

noglider 

That's really something, Bruce. Does it shift automatically? Both ways?

BruceMetras

Thanks Randy! I bought a Velocity track wheelset that was on special, then replaced the rear flip flop hub and laced in the Sachs Automatic.. it was straight forward and I am really pleased with the results.. been riding the heck out of it to the exclusion of my derailleur equipped bikes.. I did post the new removed flip flop in the fixed gear market place Here... if anyone is interested, feel free to shoot me PM.

BruceMetras

Thanks! Yes, it upshifts automatically when my cadence reaches around 90 (14mph), then away I go... the harder I pedal, the faster the shift.. you don't ease up on the pedals to upshift.. however, it will stay in high gear until your ease off on the pedal pressure (as if standing going uphill at say 10 or 11mph) .. if you approach a hill and are near the 14mph shift point, you just relax the pedal pressure and it drops into low gear.. if you are cresting a hill in low gear and heading down the other side at >14 mph, it will upshift automatically without even spinning the pedals.. you can modify the shift points by adjusting a little torsion spring inside the hub.... it's a cool piece, I'm hoping for long life!

mickey85

Crazy! I've got a sachs kickback that I love - it's in a bike I'm really not a fan of riding, but I absolutely love the hub. I will say though that with the kickback, I'm not a huge fan of stopping...you have to make sure you're in high gear, otherwise you'll be starting in high gear after you brake.

imabeliever1

I bought the steel shell model. So, yes I need the spoke washers.

philipw

Hi Bruce, beautiful bike! I'm putting a blue Sachs Automatic back in service, and I'm interested in how you modified the spring to shift later.

BruceMetras

Thanks ! .. there is probably the 'right' way to go about this, but as I really didn't know what I was doing, I just jumped in ...... with the shifting, I found there is some trial and error to get where you want to be .. first step is to find your baseline... spin it up on the stand (or take it to the street) and see what rpm/mph area it shifts...

Once you have the hub apart, you'll find a little torsion spring for the flyweights (there's only one in a stock hub) .. if you need minor shift adjustments (<3mph - approx.), you can get away with carefully bending the 'ears' on the spring.. if you need a later shift, you would increase spring tension.. earlier shift, decrease spring tension... if you need a much later shift (>3mph - approx.), then you can either add a 'second' spring to the other side of the flyweight plate.. or .. do what I did and try winding your own spring.. I got the some music wire that was slightly heavier gauge than my original spring, went on the web to see how to wind springs, and then made up a few .. if you wind your own, you'll need a sense of humor, because there is a bit of learning curve.. once you have made your adjustments (or springs), then it's back together, on the bike and test...

I almost ordered a bunch of different torsion springs that looked close from an online supplier, but decided to wind a few instead.. there is a German SITE run by Jens Hansen who is a specialist on the Sachs hubs and also can supply some of the parts... if he has stock springs, I'd order a handful and experiment. .. I'm running a Sachs Automatic on the 700c bike, and also on a 451 wheeled DAHON

philipw

Thanks for this - I'm definitely going to put your knowledge to work! I don't think it'll come to winding my own springs, but you never know...
I just got a new driving ring from Jens to replace the one I cracked last year with a hard pedal strike. When I broke it, he only had 10-knob rings, but I emailed him a few weeks ago and he had a 9-know one that fit my hub.

How are you liking the Mu Duo?

Philip

gaucho777 

Thanks for sharing. Impressive ride & jerry-rigging! Makes me want to try a similar setup.

BruceMetras

I am really impressed with it .. for a folder, it has a lot going for it.. stiff frame, light weight, no cables to the back to foul when folding, no derailleur to get knocked around, folds compactly without having to disassemble anything or remove wheels, looks great, and just plain rides nice.. with the 2 speed, it covers the territory I ride .. I have an Alfa Romeo repair shop, and sometimes shuttle cars to customer homes (sometimes 10+miles away), muffler shops, smog shops, paint shops, and I use the Dahon to get back and forth.. it will fit in the trunk of an Alfa convertible .. so for me, I love this bike..

BruceMetras

Thanks! sometimes it's nice to ride a basic, simple bike .. if you get it geared to your liking, you can really cover a lot of road on a 2 speed...

ginojames

Hi Bruce,
Thanks for sharing, I found this thread really helpful when i was adjusting my SRAM duomatic, I managed to twist the spring round another time so it was tighter, now the gear change is perfect for 20" wheels. Thanks again