Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Recumbent What IS that thing?! Recumbents may be odd looking, but they have many advantages over a "wedgie" bicycle. Discuss the in's and out's recumbent lifestyle in the recumbent forum.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 01-13-17, 09:19 PM   #26
rhunderhill
Newbie
 
Join Date: Jan 2017
Bikes:
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
FWD RWS has been done successfully

RWSB-page (rear wheel steered bicycles)
Schwab, Arend L. Schwab

I agree it's the recumbent holy grail and would allow belt drive and hub gears etc. if it could be shown to be stable at all speeds and situations. I imagine it would require a relearning of how to ride but would be entirely worth it.
rhunderhill is offline   Reply With Quote
Old 01-14-17, 11:33 AM   #27
JanMM
rebmeM roineS
 
JanMM's Avatar
 
Join Date: Jan 2006
Location: Metro Indy, IN
Bikes: RANS V3 ti, RANS V3 cromo, RANS Screamer
Posts: 13,786
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 128 Post(s)
Zombie Thread Alert!
This thread had been asleep for 12 years...................

Understatement ---> Not a lot of interest in FWD/RWS bikes. The one in the video looks well done.
__________________
RANS V3 Ti, RANS V3 Cromo, RANS Screamer
JanMM is offline   Reply With Quote
Old 01-16-17, 07:16 PM   #28
BlazingPedals
Senior Member
 
BlazingPedals's Avatar
 
Join Date: Dec 2004
Location: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, homebuilt recumbent
Posts: 9,349
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 269 Post(s)
Yeah, notice the video was posted 4 years after this thread 'died.' In the ensuing 7 years, this concept bike has remained, as far as anybody knows, a one-of-a-kind.
BlazingPedals is offline   Reply With Quote
Old 01-17-17, 12:26 PM   #29
indyfabz
Senior Member
 
Join Date: Jan 2010
Bikes:
Posts: 12,101
Mentioned: 32 Post(s)
Tagged: 0 Thread(s)
Quoted: 2000 Post(s)
Quote:
Originally Posted by BlazingPedals View Post
Yeah, notice the video was posted 4 years after this thread 'died.' In the ensuing 7 years, this concept bike has remained, as far as anybody knows, a one-of-a-kind.

This is the 4th or 5th zombie thread I have seen today that been resurrected in the last day or so.
indyfabz is offline   Reply With Quote
Old 01-17-17, 12:54 PM   #30
79pmooney
A Roadie Forever
 
79pmooney's Avatar
 
Join Date: Oct 2014
Location: Portland, OR
Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder
Posts: 3,425
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 257 Post(s)
My first thought - you start to lean right. On a conventional bike, you steer right and near instantly the front wheel and therefor the bike is back under you. Very small correction needed and you basically never stopped going straight ahead. Rear wheel steering - you still need that bike under you but to get it there yo need to steer left. As others have said above, a challenge for our brains. Maybe the way to make rear steerers ridable is to have the chain linking the rear fork and the handlebars run in a figure 8. Now balancing would take your old reflexes and ti wouldn't take too long to figure out that you steer in the opposite direction to take corners. (Like anyone who grew up sailing small sailboats with tillers and graduates to a larger boat with a steering wheel.

"But officer, I did signal my turn correctly. I just forgot what bike I was on."

Ben
79pmooney is offline   Reply With Quote
Old 01-17-17, 09:10 PM   #31
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 24,249
Mentioned: 27 Post(s)
Tagged: 0 Thread(s)
Quoted: 1800 Post(s)
Dyamaxion , Buckminster Fuller's super aero car had 2WD, front, and 1 rear steered wheel..

it was kind of high CofG, and flipped over

fietsbob is offline   Reply With Quote
Old 03-17-17, 12:48 PM   #32
Doug5150
Senior Member
 
Join Date: May 2005
Location: IL-USA
Bikes:
Posts: 1,745
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 45 Post(s)
Quote:
Originally Posted by FarHorizon View Post
Out of curiosity, has anyone made a front-wheel-drive recumbent with rear-wheel-steering?
Yea, a bunch have probably been built over the last ~100+ years or so.... by home-builders.

Quote:
It would seem that having the drive train concentrated in the front of the bike (where the power is developed) would be more efficient than having to route a mile of chain to the rear wheel.
The Cruzbike design evolved out of this concept, but it still uses conventional front-wheel-steering geometry.

Quote:
What are the physics of rear wheel steering? Would such a bike be rideable? What type of geometry would be needed to provide adequate rear-wheel-trail for stability? Does anyone make such a contraption?

The steering would probably need to be under-seat, with an offset tiller bar used to move the rear "fork." The idea is intriguing...
The desirable state of steering geometry is that a vehicle exhibits "positive stability", which means that the steering wheels will tend to return to a straight line as well as hold a straight line on their own, at any speed--even though some minimum speed may be required for this stability to function.

The mathematics for analyzing steady states of mechanical systems is Eigenvalue charts. There is one present in the article below, about halfway down the page:
https://en.wikipedia.org/wiki/Bicycl...cycle_dynamics

The Eigenvalue charts for mechanical-only rear-wheel steering shows that none devised so far can maintain positive stability. Furthermore, it appears as though such a design is not possible.

The best that can be done is to locate the majority of the vehicles mass (the rider's center of gravity) very close to the steering axis, and then the steering becomes fairly neutral--it does not tend to deviate from a straight line on its own, but then, it does not return to a straight line on its own either. These bicycles may be ride-able at typical speeds but companies generally refuse to manufacture and sell them as performance or general-use bicycles. Some are sold as cargo or commercial vehicles with cart-axle-type steering (such as tadpole vending trikes) but these are only intended to be used at VERY low speeds, and on level ground.

Note the distinction here:
1) it is not impossible to build a rear-wheel-steer bicycle that is ride-able; there's several designs that work.
2) it is probably impossible to build a rear-wheel-steer bicycle that exhibits positive stability.
A number of people have done #1 and think they've solved some great cosmic mystery--when they simply didn't have a full understanding of the problem.

What technically defines "what kind of steering" a vehicle has is its Eigenvalue chart; the common variations of front, mid and rear-wheel steering show typical kinds of charts. A casual way (that usually is correct) is to observe what wheels pivot relative to where the vehicle's mass is located. For the Kalle bike--the frame is two sections, and the rider's mass is fixed to the front section--so the rear section + wheel pivots to steer, and it is a RWS bicycle. (with the rider's mass located almost centered on the steering axis)

The Eric Wannee RWS bicycle pages show some bicycles and trikes that tried to use steering systems other-than-front-wheel-steer. Most of these toys were taken off the market and recalled due to reports of sudden crashes and injuries.

A lot of home-builders seem to think that if they're building a trike, it doesn't need to have positive stability since "it's got three wheels"--and they are likely to learn the truth the hard way. Wear your helmet! The Wannee pages have a bunch of RWS trikes that were recalled because they tended to jack-knife and roll over at high speeds and/or rough ground. And note that many of these were children's riding toys, so "high speed" may have not been higher than 5 or 10 MPH....

You can build a negatively-stable bicycle or trike if you want; it may be fun and useful at low to moderate speeds. But it's never going to be safe at high speeds and/or rough terrain, and you should think really really hard before you sell it to anyone else.

The Python is not called a "low-racer" because even tho it should have very low aero drag, it's design is negatively stable: it is unsafe at high speeds. So it is called a "touring" recumbent, not a racing recumbent. It tends to jack-knife at high speeds. And even tho the frame design is rather simple, no company has ever built and sold this design.
Doug5150 is offline   Reply With Quote
Old 03-17-17, 07:45 PM   #33
BlazingPedals
Senior Member
 
BlazingPedals's Avatar
 
Join Date: Dec 2004
Location: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, homebuilt recumbent
Posts: 9,349
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 269 Post(s)
As almost everyone knows, in the 12 years since the thread was started, Cruzbikes have gone from making FWD kits to whole bikes. They're still FW steering, though. For RWS, here's one last reference before the thread can be re-buried for another few years: Huffy Green Machine.

BlazingPedals is offline   Reply With Quote
Old 03-18-17, 08:17 AM   #34
JanMM
rebmeM roineS
 
JanMM's Avatar
 
Join Date: Jan 2006
Location: Metro Indy, IN
Bikes: RANS V3 ti, RANS V3 cromo, RANS Screamer
Posts: 13,786
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 128 Post(s)
G'night, thread............................
__________________
RANS V3 Ti, RANS V3 Cromo, RANS Screamer
JanMM is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 07:11 AM.