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alevand
human power expert

USA
3574 Posts

Posted - 10/21/2019 :  12:56:37  Show Profile  Visit alevand's Homepage  Reply with Quote
Im conceptualizing a dual 700c FWD MWB dual(duplex)vps bike. I was hoping for a single stage drive, but it looks like the wheel hub might be too wide for ankle to cassette clearance. I ordered a 700x16c Alex rim and will redo the 26 inch wheel that has the narrowed hub, as shown on some previous post. I have a 18 tooth BMX freewheel sprocket. The freewheel, though is 1/2 inch wider than the threads on the hub, a fixed sprocket would be that much narrower.. Wheel base is about 60 inches, top of fairing bubble, about 32 inches, seat height 5 inches.

C:
Tony Levand

Edited by - alevand on 10/21/2019 14:11:42

warren
human power expert

USA
6482 Posts

Posted - 10/22/2019 :  10:17:35  Show Profile  Visit warren's Homepage  Reply with Quote
Cool! How will it be different from your dual 26" SWB VPS bike from a couple years ago? Sounds like this one will be lower.
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/22/2019 :  14:27:01  Show Profile  Reply with Quote
Now THAT is interesting! Please do it so I don't have to :)
Duplex VPS (with asymmetric trapezoids, mind) seem like an ultimate steering system - you can custom-tune your steering for pretty much anything you want! For instance, you can have zero 'real', but plenty of 'virtual' negative offset for flopless steering with ton of trail, yet neat hourglass wheel cutout... bit complex mechanically though.
Cannot wait to see what you'll come up with.

Edited by - Balor on 10/22/2019 14:28:07
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/22/2019 :  14:36:40  Show Profile  Reply with Quote
quote:
Originally posted by warren

Cool! How will it be different from your dual 26" SWB VPS bike from a couple years ago? Sounds like this one will be lower.



Well, for once it will certainly be TS FWD, not MBB, given MWB and mention of two-stage drive.
It does seem very interesting - due to 'no head tube', you can run the chain exactly coaxial to 'virtual head tube' I suspect, by placing the mid-drive on the upper trapezoid... at least that's what I think he is trying to accomplish.

alevand, don't be such a tease and post at least some sketches :)
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/22/2019 :  14:40:17  Show Profile  Reply with Quote
I think the narrowest possible 'drive' hub is front hub with disk brake replaced with a sprocket.
You can even retain disk brake capability by using a hub like this:
https://ru.aliexpress.com/item/32887090011.htm

(been eyeing it for a while)
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alevand
human power expert

USA
3574 Posts

Posted - 10/22/2019 :  19:17:39  Show Profile  Visit alevand's Homepage  Reply with Quote
Been busy working on carp fairing...

I may be able to use a single stage drive with a narrowed free hub...Need pedal extenders to reach, ie, a sort of a linear drive, which also allows my ankles to remain under the front axle and cassette for clearance and also does a lot of nice things for the fairing. Drive will be 3x7 speeds.

sketch 700c-2x-fwd-fbb-dvps-susp-ld




It could have a disk brake in back, rim brake in front.



C:
Tony Levand

Edited by - alevand on 10/22/2019 19:43:43
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/23/2019 :  02:25:17  Show Profile  Reply with Quote
"Need pedal extenders to reach, ie, a sort of a linear drive, which also allows my ankles to remain under the front axle and cassette for clearance and also does a lot of nice things for the fairing."

Hah, I've thought about that for my MBB (we need an other term for that btw, pedal extenders conventionally increase Q-factor), I think I should actually experiment with that now that you mention it, because there is a limit how short a cranks you can fit without losing power and messing about with transmission, and I'm not long-legged enough to fit suspension AND 700c wheel... talking about losing power though:
in road biking world there is a dogma that high "stack height" is EVIL and should be minimized by any means possible. On the other hand, I've found no convincing explanation WHY is that true. May be an other myth?

Maybe, you should try a similar arrangement on an other bent and see whether it will cost you power/pedalling ergonomics?

An other option is to find some retired goth and borrow his platform shoes :)

Edited by - Balor on 10/23/2019 05:22:44
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alevand
human power expert

USA
3574 Posts

Posted - 10/23/2019 :  08:20:43  Show Profile  Visit alevand's Homepage  Reply with Quote
Yes, Warren there is a much better LRR tire choice with 700c, even though the front wheel is too big.

quote:
Originally posted by warren

Cool! How will it be different from your dual 26" SWB VPS bike from a couple years ago? Sounds like this one will be lower.



C:
Tony Levand
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/25/2019 :  09:52:32  Show Profile  Reply with Quote
A small question concerning VPS: do you think whether using a large rubber isolator (say, cylindrical, 2 by 2 inches, rated for 100kg) will work as a rubber ball joint for simplex vps? Or, likely, a stack of two in series.
Seems nice - service free, built-in steering damping and return to center force, a couple cm of suspension travel, zero backlash. Am I missing something? It is a bit on the heavy side, perhaps, and not really low profile.
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alevand
human power expert

USA
3574 Posts

Posted - 10/25/2019 :  10:27:05  Show Profile  Visit alevand's Homepage  Reply with Quote
Might work on the frame side of the link to have a flex joint, would have to flex in 2d for both steering and suspension. Rubber isolator would have too much compliance. A ball bearing might work if its on a flex plate. The ball joint rod ends would be best, not hard to come by. These have more rotation than the Helmholtz type ends, with seal: https://www1.mcmaster.com/catalog%2f125%2f1294 I cut the female threads off and weld it to the frame. When they wear and get play, just hit the end with a hammer to close it up some. 3/8 or 7/16 size work.

quote:
Originally posted by Balor

A small question concerning VPS: do you think whether using a large rubber isolator (say, cylindrical, 2 by 2 inches, rated for 100kg) will work as a rubber ball joint for simplex vps? Or, likely, a stack of two in series.
Seems nice - service free, built-in steering damping and return to center force, a couple cm of suspension travel, zero backlash. Am I missing something? It is a bit on the heavy side, perhaps, and not really low profile.



C:
Tony Levand

Edited by - alevand on 10/25/2019 18:09:36
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/25/2019 :  11:27:44  Show Profile  Reply with Quote
Yea, I'm choosing between a rod end like this and a large rubber isolator. Both have merits - rod is lighter and smaller but might develop play (interesting point about 'percussive maintenance'), isolator is nearly indestructible and actually allow for some suspension and, most importantly, add some return-to-center force that is not dependant on trail or negative flop.

"Rubber isolator would have too much compliance." Isn't it the whole point of a having a BALL joint instead of a bearing - to have side-to side (and back and forth, in case of suspension) compliance, due to axle performing complex articulations during steering? And a ball joint have 100% compliance until you hit a limit (which you should design not to).

It may not have *enough* 'twisting' compliance for steering, in fact, so I think about using two in series, that should likely do it.

What am I missing?
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alevand
human power expert

USA
3574 Posts

Posted - 10/25/2019 :  11:57:14  Show Profile  Visit alevand's Homepage  Reply with Quote
No, rotation but not translation. isolators are made for linear compliance. They isolate vibrations. You might mean a rubber bushing, commonly found on car suspensions, annular rubber encased in a tube, ID and OD with radial stiffness some axial compliance and free rotation in one axis.

C:
Tony Levand

Edited by - alevand on 10/25/2019 18:06:48
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/25/2019 :  13:01:38  Show Profile  Reply with Quote
quote:
Originally posted by alevand

No, rotation but not translation. isolators are made for linear compliance. They isolate vibrations. You might mean a rubber bushing, commonly found on car suspensions, annular rubber encased in a tube, ID and OD with radial stiffness some axial compliance and free rotation in one axis.



C:
Tony Levand



Well, it was not designed for that, but I *think* it can be used anyway.
That's what I mean:

https://www.youtube.com/watch?v=ALfOHBuz36M

That's 20mmx20mm isolator rated for 15kg axial load, it has quite enough compliance, including 'twisting' compliance, in all directions - and provides tangible 'return to center' force. Similar isolators are often uses as 'steering dampers' on handcycles, and also used as standard equipment on Flevobikes for same purpose. Replace it with a 50mm x 50mm isolator and it should work.

Obviously it does not "like" shearing loads, but lower links 'triangulate' the steering and take all the braking loads, so it should never actually experience them.

My only concern is that twisting it too much (40+ deg in one direction) might delaminate the rubber, hence 'two in series'.
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purplepeopledesign
recumbent guru

Canada
702 Posts

Posted - 10/25/2019 :  15:33:27  Show Profile  Reply with Quote
I upgraded the trailing arm rear suspension of a cargo trike with lateral control links comprised of threaded rod, Nyloks and faucet cone washers. Each end of the link mounted to plates in the following order: Nylok, cone, plate, cone, Nylok. The threaded rod was about 6" and the end would swing through about 1.5" of arc. Maybe not as precise as a spherical bearing, but it works great as a way to keep camber under control during a turn.

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/
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Balor
recumbent guru

Russia
800 Posts

Posted - 10/25/2019 :  16:47:28  Show Profile  Reply with Quote
quote:
Originally posted by purplepeopledesign

I upgraded the trailing arm rear suspension of a cargo trike with lateral control links comprised of threaded rod, Nyloks and faucet cone washers. Each end of the link mounted to plates in the following order: Nylok, cone, plate, cone, Nylok. The threaded rod was about 6" and the end would swing through about 1.5" of arc. Maybe not as precise as a spherical bearing, but it works great as a way to keep camber under control during a turn.

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/



Sounds interesting, but how about a photo?
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alevand
human power expert

USA
3574 Posts

Posted - 10/25/2019 :  18:09:10  Show Profile  Visit alevand's Homepage  Reply with Quote
I received the rim, though I don't want to tear apart my 26 inch wheel for the hub. I need to find one that I can cut down.

C:
Tony Levand
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purplepeopledesign
recumbent guru

Canada
702 Posts

Posted - 10/26/2019 :  03:31:04  Show Profile  Reply with Quote
Relationship with client ended before I could take photos. You'll just have to imagine it. Works like a Weissach link.

:)ensen.

Those who claim to be making history are often the same ones repeating it.

Video of my trike
http://www.youtube.com/watch?v=MdSLRD_2vzc
Photos of my trike
http://www.flickr.com/photos/purplepeople/
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alevand
human power expert

USA
3574 Posts

Posted - 10/30/2019 :  12:30:33  Show Profile  Visit alevand's Homepage  Reply with Quote
I ordered a steel threaded hub, that I hope I can narrow up and inch or so. I don't know if I could use a 7 speed parallax freehub on drive side and steel on hub half on the other, that way the steel side spokes will be further outboard , thus the hub could be 3/8 inch narrower or maybe its not worth the effort.

C:
Tony Levand
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alevand
human power expert

USA
3574 Posts

Posted - 10/31/2019 :  09:32:38  Show Profile  Visit alevand's Homepage  Reply with Quote
Im thinking along these lines:

C:
Tony Levand
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alevand
human power expert

USA
3574 Posts

Posted - 12/13/2019 :  16:13:53  Show Profile  Visit alevand's Homepage  Reply with Quote
I may be able to fit this with the Black Stallion fairing, if I cut the fairing top off and narrow it 4 to 5 inches.

C:
Tony Levand
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alevand
human power expert

USA
3574 Posts

Posted - 01/02/2020 :  12:36:04  Show Profile  Visit alevand's Homepage  Reply with Quote
I decided not to try to marry an aluminum cassette free hub to a steel hub, I will just use a 7 speed freewheel and threaded steel hub, I will narrow it 1.25 to 1.5 inches, 36 spokes. I have reversed the non-drive side flange and its even with the axle lock nut. I will also grind off some of the shoulder, this will move the freewheel inboard maybe 1/8 inch. I should have enough clearance for my ankles.

... I will cut it 1.44 inches, but I cant use a tubing cutter since the hub tapered.


.... I forgot to clock the flanges, oh well good enough...

I ordered a 7 speed freewheel, 14-28. Not much choice there.

I ordered 282 mm spokes for cross 2 x 36.

C:
Tony Levand

Edited by - alevand on 01/02/2020 17:07:58
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alevand
human power expert

USA
3574 Posts

Posted - 01/20/2020 :  08:06:56  Show Profile  Visit alevand's Homepage  Reply with Quote
Don't buy spokes from SourceBMX, they are not in Kentucky as claimed, but ship from the UK and takes a month to get them. Jerry had the same experience with them.

C:
Tony Levand
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alevand
human power expert

USA
3574 Posts

Posted - 01/22/2020 :  12:03:33  Show Profile  Visit alevand's Homepage  Reply with Quote
I laced up the wheel cross 2, no dish. I needed spoke washers, as the steel hub is thinner than an aluminum. I used aluminum rivet backup washers, 1/8. Hub is 82 mm wide lock nut to lock nut and will have a 7 speed freewheel, it is 38 mm flange to flange an has about the same spoke angle as a standard dished wheel drive side.



Im thinking of making the forks from 7/8x.028 crmo tube,it harder to work with than 3/4x.035, about same weight but 30% stiffer. I am going to use the Sun Tour S5 braze on derailleur,the hanger brazes to the stay in front of the axle, in this case the fork above the axle.This derailleur doesn't stick out like the dropout mounted ones do.

C:
Tony Levand

Edited by - alevand on 01/22/2020 13:17:52
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alevand
human power expert

USA
3574 Posts

Posted - 01/23/2020 :  16:36:19  Show Profile  Visit alevand's Homepage  Reply with Quote
I made progress on the fork today, though I need to cut off the length under the freewheel and put a wiggle in it to clear my calf and ankle. The steel hub and freewheel are heavy.

C:
Tony Levand

Edited by - alevand on 01/23/2020 16:36:44
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Balor
recumbent guru

Russia
800 Posts

Posted - 01/24/2020 :  02:55:47  Show Profile  Reply with Quote
You still intending to use 'offset pedals'? I suspect making the 'offset' too long may upset pedalling dynamics after all - a few cm seems fine though.
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alevand
human power expert

USA
3574 Posts

Posted - 01/24/2020 :  07:32:52  Show Profile  Visit alevand's Homepage  Reply with Quote
Half a meter.

I cut off and welded in a wiggle in the drive side of the fork.

I cant use the sun tour s5 derailleur, because the fork is too far behind the axle, I will weld in a hanger for a more standard one.


Some parallax, imported into cad...



C:
Tony Levand

Edited by - alevand on 01/24/2020 17:35:03
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