[Drew Diller]

I'm building a dingle speed (not a typo) mountain bike with a Hammershmidt crank set. I mean building, as in the frame also, so if the answer to the following is "no" I guess I will look at making one:

I think the HS shifter is kind of redundant. It has two speeds, not three. I want to press a lever to change gear, and press that same lever again to change back.

Does this sort of thing exist? Been searching a while.

I guess if I had to make one I'd fashion it after a ratcheting wire crimper: you squeeze up to a certain point, and it will hold there, but if you _really_ squeeze, the hold will release and the handles will back away when you let up. (Thinking aloud here I guess.)

 

[anthony.delorenzo]

Coupla thoughts, first is that the Hammerschmidt is not super efficient. You'll definitely lose some of the efficiency advantages of a singlespeed.

Second, if you're looking for the total simplicity maybe think about a Schlumpf mountain drive? Shift it with your foot. It also requires some customization of the BB so would be good for a custom project.

 

[Drew Diller]

True on efficiency, and the Schlumpf Triebwerk is unavailable (I asked). I'm not too keen on needing my foot in a certain position in order to shift, but I wouldn't know until I rode one. Admirably, the guy behind Schlumpf actually makes efficiency claims (95% to 97% if I remember).

I'm not super concerned as I am slow and this is going on a fat bike. I prefer to avoid front derailleurs in particular even if it costs me speed.

The HS is sitting in my kitchen and I will use it. Really just want to know if toggle shifters exist.

 

[dr.welby]

Some kind of a shock lockout lever?

Maybe look at lawnmower and other small engine throttles/brakes?

Old Bendix 2-speed shifters? Or redo the plates in the old style Sturmey 3-speed shifters?

 

[evrac]

I see what you're saying. Like the button on the back of a pen. Once for on, again for off.

Look at the new sram double-tap shifter. It works with one button, but handles many gears. Doubt it would pull the right amount of cable though, but maybe.

Looks like you'll need to design it.

 

[Drew Diller]

evrac, brevity is a skill, thank you!

I'll look into these, thanks guys.

 

[Drew Diller]

The SRAM double tap exists in flat bar form....

Doing some reading, it looks like the average SRAM cable pull per shift is about 3mm. This is well short of the ~11mm the HS shifter pulls.

That said, it would be far simpler to make a J-tek ShiftMate style pulley and couple that to a double-tap shifter.

 

[brent878]

what about something like this?
https://www.blueskycycling.com/view..._medium=feed&utm_campaign=GoogleProductSearch

I have one at home but haven't installed it yet. Not sure how much it pulls the cable. They also have a poplock adjust that you can adjust how much cable it pulls to a certain extent.

 

[Drew Diller]

brent878, even better... could I persuade you into measuring the cable pull if you have a caliper handy?

 

[brent878]

I'll try and do that tonight. I actually have the older poplock on my other bike too. It is the one in the bottom picture but it doesn't have the adjustment knob on it. So atleast I can give you 2 measurements but they should be the same as they are interchangable. The only unknown will be if you decide to use these is the one with adjust, I won't know how much it will allow you to adjust.

 

[brent878]

ok so I couldn't find my calipers but going off a tape measure it was around 3/4" of cable pull.

 

[Drew Diller]

Whoa, plenty!

Thanks a bunch

 

[brent878]

it doesn't have a spring so your deralier or what ever your going to hook it to will need to pull the cable back when you release it. If you need a more preciese measurement I can look for my calipers. I think I might remember the last place I put them, haha.

 

[Drew Diller]

Yep, the HS has a sufficiently strong return spring. No worries on the caliper, 3/4" is way more than I need

 

[brent878]

oh great. Hope the project works out. Sounds like a cool project. And by looking and holding the two remote lock outs I think the pushloc is better made and looks alittle better.

 

[orangeskill]

use a friction shifter. cheap, simple, no adjustments, lightweight. I use one for my 2x9 setup.

 

[Drew Diller]

Already ordered a PushLoc, and it arrived the next day (wtf?!). Quite pleased, it has a nice action to it.

It has more than enough cable pull, so I'll need to devise or find a little spring worm for pulling the extra slack that the Hammerschmidt doesn't quite pull back.

 

[Drew Diller]

So here's what I ended up doing (buying) to fix the excess cable slack problem.

I asked Ryan at Jtek Engineering if he'd make me a custom ShiftMate. He said sure, but that the ratio I was asking for was more extreme than he's accustomed to, so it would take some time to get a special sized bearing, and that it might not even work.

It took some time for the bearing to arrive, but it works great!

 

[Drew Diller]

Oh and since you guys aren't necessarily visitors of the Fat Bike forum, here is the first Fat Tire Bamboo bike I finished.