A picture's worth a thousand words....... (title edited)

[Miles]

I'm late to this discussion but allow to also add my appreciation of how great the drive looks and performs. What would be the possibility of adapting this drive system to use with a Sturmey Archer 3 spd internal/9 spd cassette hub described in this thread?

http://endless-sphere.com/forums/viewtopic.php?f=31&t=24449

Particularly for a dual right hand drive?

Rich

That's pretty much the set-up I have on my eMoulton.

 

[Miles]

gates 8mm poly gt 12mm drive belt / gates carbon gt 8mm 12 mm crank pedal belt

Someone else using the Strida pulley

 

[richmpdx]

Miles,

Thanks for the response. As a long time lurker, only occasionally posting, I am aware of your very nice Moulton build. It has a great many desirable features and I am sure it has helped motivate many to consider non-hub drives. However, your build seems out of reach for the fabrication/mechanically challenged, not to mention the unique electric motor. So I should have phrased my question better. If I understand Matt's drive correctly (which is certainly questionable), the large rear pulley is attached to the disc brake mount. Would Matt consider modifying the large rear drive pulley so that it could mount on the spline of the new 3 speed SA hub that has splines to accept a standard 9 spd cassette? Then his drive might be accessible for those not so capable fabricating adapters, etc.

Rich

 

[Miles]

So I should have phrased my question better.... Would Matt consider modifying the large rear drive pulley so that it could mount on the spline of the new 3 speed SA hub that has splines to accept a standard 9 spd cassette? Then his drive might be accessible for those not so capable fabricating adapters, etc.

Ok, I'm with you. I'll let Matt answer for himself

In case it's of interest, the earlier (MkII) Strida pulley fixed onto an 18t freewheel. It would be relatively simple to mount one onto the standard cassette driver, using a splined track sprocket.

It's possible that you could adapt Matt's existing pulley design by bolting a splined track sprocket to its six 44mm BCD holes (standard ISO brake mount)? A pulley on the RH side would probably need less offset, though.

 

[j3tch1u]

matt, do you know if those sprags are sensitive to heat? i want to weld a couple together.

 

[recumpence]

I am not sure about adapting the pulley.

As for heat, there are no rubber parts on the sprague that I can see. I believe it is all metal. Even the shields are a sintered material of some sort. The issue I have have with welding is warping.

Matt

 

[j3tch1u]

I am not sure about adapting the pulley.

As for heat, there are no rubber parts on the sprague that I can see. I believe it is all metal. Even the shields are a sintered material of some sort. The issue I have have with welding is warping.

Matt

does it appear as if the sprag can be disassembled? i'm thinking the springs would be susceptible to heat.

 

[Miles]

Ben,

The tolerances must be pretty tight - I should imagine that the slightest distortion and they're buggered.... as Matt implied.

Why do you need to weld them? Can you not just press them into a sleeve?

 

[j3tch1u]

Ben,

The tolerances must be pretty tight - I should imagine that the slightest distortion and they're buggered.... as Matt implied.

Why do you need to weld them? Can you not just press them into a sleeve?

no, there is not enough space for a sleeve. i'm using csk15 (35mm OD) which has just enough material to cut threads (for the fixed sprocket and freewheel).

csk12 is 32mm OD so the sleeve would be too thin. csk8--not strong enough and the shaft would be too small.

i may not need to weld them together if enough thread from the freewheel straddles over the second sprag.

was thinking of just tig spot welding 8 points around the circumference using the smallest tungsten i have. the 2 sprags will not see any radial force /w respect to each other since they'll be locked via key.

 

[mdd0127]

Doing anything heat wise or any machining on CSK will affect it's rating because the HAZ or machined/threaded areas will weaken the outer race. If they've got another chunk of metal screwed onto them though, it will reinforce them enough to cancel that.

I've had to tig a few sensitive little things together and usually just end up heat sinking anything that I don't want to get too hot.

In your case, I'd turn a piece of aluminum to slide both of the bearings on, then turn the ID of a piece of tube for the bearings slip fit in. Then cut a little window in the tube and make your welds through it. You'll have to let each weld cool and dremel it back smooth to rotate it for the next weld but it doesn't take too long. The pipe and mandrel will keep everything aligned and sink the extra heat off of the races. Also, make sure to leave a tiny space between the two bearings when you weld them. Things expand a lot. You just want to heat each side alternating back and forth until you get a tiny puddle going on each size. They'll join up when the time is right. I've done precision shafts in industrial gearboxes, rock crawler drive shafts, and some jewelry work using this method and it works.