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-   -   Double decker tandem recumbent? (http://www.bikeforums.net/recumbent/349732-double-decker-tandem-recumbent.html)

beelz 10-03-07 08:39 AM

Double decker tandem recumbent?
 
I posted this as part of another thread, but since it's a separate subject in itself, hope to get more responses as a separate thread.

One idea I had that I haven't seen anywhere: A recumbent tandem trike designed so that the passenger seat is above the driver's seat, rather than behind it. A double-decker tandem, in other words. That would have a smaller footprint, and also, if the driver was riding solo, the top seat could be adapted (with foldouts or by other means) to be a roof to protect from rain and sun and/or to carry cargo. Also, the vehicle would be high, which solves the problem of recumbents being too low to be seen by other drivers.

I have no idea if this is workable or not, I hope people here will tell me if it could work.

One person already pointed out two possible shortcomings: a high center of gravity making turns less stable, and the top rider dripping sweat onto the bottom rider. These don't seem like necessarily insurmountable problems to me, so would love to hear more opinions/ideas. Also, a link if you've actually seen a double decker recumbent on the net.

cat0020 10-03-07 09:12 AM

What do you think of this one:

http://img.photobucket.com/albums/v5...o/SUC50229.jpg

Stoker sit in front of the captn, full view of vision for both riders..

beelz 10-03-07 09:37 AM

yeah, but it's criminal to make your passenger sit on a wedgie!

cat0020 10-03-07 10:24 AM

Actually, the passenger sit in front of the captn, who sits upright and control the tandem from behind the stoker.

BlazingPedals 10-03-07 10:42 AM

Double-decker tandem: How would the stoker climb aboard? Severe balance issues, as well as stability issues when braking or climbing. A double-decker would be extremely dangerous to ride!

The half-recumbent tandem is a Taiwanese version of the venerable Bilenky Viewpoint tandem, which is itself base on the older Opus III Counterpoint tandem.

jeff-o 10-03-07 11:02 AM

Quote:

Originally Posted by BlazingPedals (Post 5382375)
Double-decker tandem: How would the stoker climb aboard? Severe balance issues, as well as stability issues when braking or climbing. A double-decker would be extremely dangerous to ride!

+1.

It would have to be incredibly wide to counteract the balance issues while turning. A trike like this could only be a novelty item during parades.

vik 10-03-07 11:11 AM

Quote:

Originally Posted by jeff-o (Post 5382540)
+1.

It would have to be incredibly wide to counteract the balance issues while turning. A trike like this could only be a novelty item during parades.

+1 you wouldn't make it around the first corner upright...:eek:

BlazingPedals 10-03-07 12:53 PM

I wasn't even thinking in terms of side-to-side balance. With the center of gravity up that high, you'd have to have a long wheelbase or else gentle braking would tend to make the bike do an endo. Likewise, going up a steep climb, the bike would spontaneously tip over backwards. Giving it a longer wheelbase to fix the problem would put you right back where you started wrt having a small footprint, but with the disadvantage of how the stoker is expected to climb up to the 2nd floor seat.

beelz 10-06-07 08:34 AM

Look, it's simple. The upper rider simply steps on the stomach of the lower rider and the lower rider then raises his knees so the upper rider can then step on his knees to get up to his or her seat. You think I didn't think of everything? :D

As for the high center of balance...does it have to be that high? What about making the upper seat just as high as it needs to be in order to give the lower rider room for his reclined body and his pedaling motion, and no higher. Would that really be too high? I can't really picture it, so I'm just asking. Seems to me that you wouldn't need that much room.

beelz 10-06-07 08:36 AM

Actually, why couldn't the upper rider board the vehicle first, using the lower seat as a stepladder to get up to the upper seat? Then the lower rider boards.

You could also have some kind of lightweight ladder. Ladders can even be made of rope, can't they?

Floyd 10-06-07 09:04 AM

If you are talking 2-wheeler the balance issues are compounded...top rider leaning one way, bottom another... +1 on the possible, and that is only possible circus ride or in a parade.
peace

rohorn 10-06-07 02:07 PM

It seems nobody remembers (or ever saw) this one:

http://www.recumbent.com/cartoon2.jpg

beelz 10-07-07 08:35 AM

Rohorn, where did you find that cartoon??? But that's much higher than it needs to be.

beelz 10-07-07 08:37 AM

Imagine a really low recumbent trike. Then add a second deck to it, but only high enough to clear the lower rider's leg rotation. Would that need to be any higher than maybe 4 feet high? That's not that high, is it?

Remember it's a trike, not a bike...

also maybe with smaller wheels it can get lower.

lee_rimar 10-07-07 11:27 AM

Well, I see these aroun Portland sometimes...

http://en.wikipedia.org/wiki/Tall_bike

---
http://upload.wikimedia.org/wikipedi...3/Tallbike.jpg
---
So tall isn't necessarily impossible (even tough I've never seen how someone mounts/dismounts a tall bike). But you'd only have to make it a little taller & longer to leave room to stack more than one rider...

vik 10-07-07 02:18 PM

Quote:

Originally Posted by beelz (Post 5407800)
Imagine a really low recumbent trike. Then add a second deck to it, but only high enough to clear the lower rider's leg rotation. Would that need to be any higher than maybe 4 feet high? That's not that high, is it?

Remember it's a trike, not a bike...

also maybe with smaller wheels it can get lower.

A trike is much worse for a vertical tandem than a 2 wheeled bent. A high two wheeled bent can lean in corners where a vertical tandem trike will just fall over.

This is why 2 wheeled "tall bikes" like the one pictured above are ridable.

rohorn 10-07-07 09:54 PM

Quote:

Originally Posted by beelz (Post 5407796)
Rohorn, where did you find that cartoon??? But that's much higher than it needs to be.


http://recumbent.com

I first saw it in RCN around 8 years ago.

BlazingPedals 10-08-07 10:58 AM

Quote:

Originally Posted by rohorn (Post 5404770)
http://www.recumbent.com/cartoon2.jpg

Rohorn, where did you find that cartoon??? But that's much higher than it needs to be.

What is too tall about it? Do you expect to obscure the lower rider's view? I don't think you've completely thought everything through, especially starting and stopping. If the top rider mounts first, the other rider must hold the bike. It would be almost assured that the bike would tip away from the holder, ensuring the top rider would fall before getting started. If the top rider got in the top seat, the lower rider would then need to roll the bike and get in while the bike was rolling (without upsetting the bike) - a hopeless task. Making the lower rider power and/or balance the thing while the top rider climbs and mounts would be similarly tricky. The only conclusion I could make is that it would be impossible to get it safely started or stopped without bracing against a tall ladder.

StephenH 10-08-07 11:32 AM

One of my brainstorms is the 2-story backpacking tent, and I've had problems working the details out there as well.

On mounting the bike above...put a rubber tire around the upper sprocket, maybe 16" tire or so. Fix the seats back a little further. Tip it over frontwards with the guys standing, and get started like that. Then on 3, they do a wheelie and flip it to the back wheel and off they go.

beelz 10-12-07 09:31 AM

Quote:

Originally Posted by BlazingPedals (Post 5414035)
What is too tall about it? Do you expect to obscure the lower rider's view? I don't think you've completely thought everything through, especially starting and stopping. If the top rider mounts first, the other rider must hold the bike. It would be almost assured that the bike would tip away from the holder, ensuring the top rider would fall before getting started. If the top rider got in the top seat, the lower rider would then need to roll the bike and get in while the bike was rolling (without upsetting the bike) - a hopeless task. Making the lower rider power and/or balance the thing while the top rider climbs and mounts would be similarly tricky. The only conclusion I could make is that it would be impossible to get it safely started or stopped without bracing against a tall ladder.

Um, it's a TRIKE, are you aware of that? Not 2 wheels, 3. Do your criticisms still apply?

BlazingPedals 10-14-07 07:54 PM

For a trike you could build a ladder into the frame (more weight, but who cares?!!) Stability would depend on how big the base triangle was, but the bottom rider would probably have to mount first in any case. Trikes get most of their stability by having the weight down low, so a two-story trike of normal track and wheelbase would be very susceptible to tipping over in turns, and maybe even in a straight line if the road had enough of a crown.

mtnbk3000 10-14-07 07:55 PM

Quote:

Originally Posted by lee_rimar (Post 5408411)
Well, I see these aroun Portland sometimes...

http://en.wikipedia.org/wiki/Tall_bike

---
http://upload.wikimedia.org/wikipedi...3/Tallbike.jpg
---
So tall isn't necessarily impossible (even tough I've never seen how someone mounts/dismounts a tall bike). But you'd only have to make it a little taller & longer to leave room to stack more than one rider...

the time i rode one i was next to a pile of logs and just hopped on

pengyou 10-29-07 06:26 AM

The main reason why 'bents are so effecient is that they have such a low profile. If you have a 2 story bent, now matter how you work out balance or other issues you will have more wind resistant than a normal wedgie...so what's the point? Unless...you want to have a pretty girl ride upstairs...but we won't go there ;)


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