Phaser g-boxx style middrive

crossbreak

crossbreak

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Moved from the ES BB drive thread http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=45313&start=60#p661409

This is the phaser g-boxx jackshaft design with build-in 9-speed shift transmission. Gear range is 544% (28T to 12T)

Feel free to post your ideas and develop it further, plz also post cross references.

The Daniele Phaser g-boxx patent WO 2006/087750A1 looks a bit different and cannot work at all IMO, since the chain strength is exceeded. Due this fact I guess it will never be build in series as patented. But this could still be a patent violation. I solved that issue by an additional overdrive stage. The construction may also get in conflict with the g-boxx patent of SR due this.
 

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Awesome!
I'll admit up front I have a bias towards folding bikes. But the bike I'm riding as my workhorse now, a folder with rear (full actually) suspension lends itself to a design like this. Notice in the picture below that the center of the bike shown has four outside attachments, plus the bottom bracket/cranks: The front hinge, the suspension pivot, the shock mount, and the seat post mount.
Folder%2520Center.jpg

The rest of the structure can be yanked out of the existing bike and replaced with something very similar to what you've drawn.

What's great about this is the modularity. Folding bike or not.

I can imagine a small run of 10, 20 or 30 sets of parts someone designs and builds (maybe KickStarter funded) that are modules people buy, and build a bike around. An ES design, that meets enough of our needs to have great design, and enough sales to make the price workable.

For all its other advantages, this middrive can be so much more... It's modular. Think: Farfle's Genesis swing arms, only designed to mate with this drive.

**Subscribed**, this is brilliant.
 
g-con is a modular standard by Universal Transmissions GmbH check this link for reference http://www.g-boxx.org/07-transmission-suspension.html

Miles said:
I like your use of concentric shafts....
Click to expand...
this indeed has some advantages. they are listed on the reference page above.

I made a short calculation about the chain force in a Phaser gearbox without primary overdrive, I made some assumptions that may not meet the actual drive:

riders weight force: 1000N
crank arm length: 175mm
resulting pedal torque: 175Nm
smallest sprocket: 13T
sprocket diameter: 53.06mm

resulting chain force: 175Nm/(53.06/(2*1000))=6596,3N which is far too much IMO, as stated in the first post. The breaking force of a bike chain is about 8200N. With 3:1 overdrive we would get 2200N which seems to be acceptable.
 
crossbreak said:
I made a short calculation about the chain force in a Phaser gearbox without primary overdrive, I made some assumptions that may not meet the actual drive:

riders weight force: 1000N
crank arm length: 175mm
resulting pedal torque: 175Nm
smallest sprocket: 13T
sprocket diameter: 53.06mm

resulting chain force: 175Nm/(53.06/(2*1000))=6596,3N which is far too much IMO, as stated in the first post. The breaking force of a bike chain is about 8200N. With 3:1 overdrive we would get 2200N which seems to be acceptable.
Click to expand...
Well....... there are a lot of assumptions there but, leaving them aside, you have introduced the overdrive which reduces torque through the gearbox from the pedal input but you have added a torque input from the motor........ The chain between the gearbox and the wheel can be any type you like, of course.
 
This is a very interesting design. Are you BUILDING the box or is it something you can buy?
 
It would be quite a challenge to build... Something based on the Petespeed would be easier but wouldn't have as great a range. I think I would just go for a one chain for each sprocket pair type, four wide ratios.
 
I was thinking of something like a normal derailleur, between the jackshaft and the wheel but with the cassette on the jackshaft. 4 speed, heavy duty 1/8" chain....
 
I was thinking of something like a normal derailleur, between the jackshaft and the wheel but with the cassette on the jackshaft. 4 speed, heavy duty 1/8" chain....
Click to expand...

This would be a non-enclosed setup which is all I want to avoid. An enclosed drive would survive multiple times as long when used by me (not the one who does much cleaning). Now that I have to use a rear hubmotor with cassette, since my tongxin drive with i-motion-9 gearhub is gone, I really learn how much suffer an unenclosed derailleur in fact is.


BUT... an enclosed jackshaft derailleur drive at the rearwheel would be technically awesome IMO. Would just look really ugly.
 
You have a single sprocket on the rear wheel. The 4 speed cassette is on the jackshaft and can be moved across it. The point where the chain exits the gearbox restrains it laterally when the cassette is shifted. One less drive stage. Higher pivot point.
 
Ok I get it. This is a great idea!

It would be quite wide when using more than 4 sprockets. for a 4-speed drive this seems reasonable. It would also meet the criteria of being universal fit for almost every bike (I aim on the ES BB drive topic). People that want more than 4 gears and the pain of a rear derailleur can also still use it. 3speed would be also something worth thinking about.
 
One could also just use a normal front derailleur. Keeps the possibility to use an enclosed chain to the wheel and is even simpler to build.

Since one can use 3 much smaller front sprockets, the distances between the 3 chain outputs are smaller.
 
I guess 3 or 4 depends a bit on what range you need, given that there's a limit to the jump between sprocket sizes that can be easily changed. 3 would be more compact.....
 
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