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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 04-23-08, 11:27 PM   #1
zonatandem
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TriBent . . . 3 wheels in-line!

Saw a 3 wheeled Turner recumbent tandem at the big GABA Bike Swap meet last Sunday.
Unusual . . . 3 wheels in-line!
Check out turnerbents@aol.com and scroll down to T-4-2.
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Old 04-24-08, 07:18 AM   #2
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http://turnerrecumbents.com/
Never seen such a thing. Interesting.
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Old 04-24-08, 10:24 AM   #3
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Why?
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Old 04-24-08, 12:35 PM   #4
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i wonder how it feels while tuning...
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Old 04-24-08, 01:31 PM   #5
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Why?
one more tire to flat.
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Old 04-24-08, 01:42 PM   #6
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From the website:

With two riders providing twice the power as an ordinary bike, much higher speeds on a tandem are possible. Safety becomes paramount, especially when a front-tire blowout, or slipping on a sharp turn, can turn a good day into a disaster. But with the T-4-2, the extra front, in-line wheel provides a critical safety backup. A flat will just slow you, not throw you.

The second front wheel provides this safety without compromising speed or agility. That is because both front wheels are connected by the steering bar, so that even the tightest turns at speed are "locked-in the track" for maximum traction and control, similar to a rollerblade skate. Both front wheels have their own brakes, controlled by a single caliper, thereby increasing front braking power by 100%. All told, there are four sets of brakes, with the driver controlling all three wheels, and the stoker rider also controlling the rear for the ultimate in braking safety.
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Old 04-24-08, 09:33 PM   #7
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It will not revolutionize 'bent tandems.
Agree, one more tire to flatten, more weight. Does add an extra brake. Comes apart.
Talking with the fellow that was showing it, he he claimed that 'if you get a flat you can keep riding'. Asked him 'what if you flatten the rear tire?' Duh!!! The look on his face was priceless.
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Old 04-24-08, 11:32 PM   #8
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"new and improved" model will have 2 rear wheels to increase the odds of getting a flat somewhere ...
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Old 04-25-08, 06:13 AM   #9
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I'm reminded of the short-lived and somewhat bizarre 6-wheeled Tyrrell P34 F1 car developed to circumvent F1 regulations in the mid-70's. The rationale and execution of the P34 design was a bit flawed, but far more sound than the T-4-2. If flat protection was the goal, use a tubeless tire/rim with Slime already in the tire or just drill a second valve stem hole in a rim and stuff two tubes in the tire, each inflated to 1/2 of the total desires PSI. Neither one of these are fool proof either, but they'e certainly more pragmatic than adding a second wheel. I can't imagine how hard that thing would be to ride in a strong cross wind.

One can only hope this was a brilliant marketing tool developed to give some visibility to Turner vis-a-vis a media stir / threads like this moreso than a serious design.
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Old 04-25-08, 04:24 PM   #10
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Turner's been building bents for a long time (20-some years) and this T-4-2 seems a bit off the wall.
Another innovation looking for a problem?
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Old 04-25-08, 04:27 PM   #11
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Turner's been building bents for a long time (20-some years) and this T-4-2 seems a bit off the wall.
Another innovation looking for a problem?
Didn't look close enough to see, All the chains criss-crossing made me ill, but what keeps the two forks in unison?
Imagine if that went out on a ride?
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Old 04-25-08, 04:53 PM   #12
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Forks stay in unison with a connecting rod, barely visible in enlarged photo.
All those criss-crossing chains on long 'bents could be eliminated by utilizing cross over drive as on a tandem. Terry Osell, a now retired builder in Minnesota, built his 'bents that way.
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Old 04-26-08, 01:48 AM   #13
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Should give you twice the bounce when going over a speed bump, driveway cut out or RR tracks. Think I will pass on this.
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Old 04-28-08, 05:42 PM   #14
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I have a question.... why does it say that it's safer for the rear rider to have a brake too ("and the stoker rider also controlling the rear for the ultimate in braking safety"). Why should the person in the back have to hit the brakes when they cant see anything??! Not really safe at all if you ask me?
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Old 04-28-08, 06:02 PM   #15
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why does it say that it's safer for the rear rider to have a brake too
Looking at the photo of the beast, it would appear as though the stoker has control over the somewhat smallish diameter rear disc, whereas the captain is controlling the rim brakes on the front and rear wheels... most likely with both front brakes being controlled off the same lever (just a guess).

Assuming the inventor based some of his bike's features on what he's observed on other tandems, the stoker's control over the rear disc is used to provide the tandem with a drag brake to continuously scrub off speed on long or steep and challenging descents, while the captain uses the rim brakes to slow the tandem as they enter turns, etc... This same configuration is not all that uncommon on tandems, except that an Arai drum brake is usually used as the drag brake given it's incredibly high heat tolerance.

As for how the stoker knows when and how much to apply, initially it takes a lot of communication with the captain, e.g., give me about 50% on the drag brake sweetie! For teams that use a stoker controlled drag brake on a frequent basis, over time the stoker and captain will just work out their technique where using the system doesn't take a lot of communication: the stoker will just know instinctively when it will need to be used or know just how hard to apply it when the captain calls out for some drag brake control. This is a actually not a bad way to enhance the whole concept of 'team work' on a tandem.

Frankly, although most stokers may not realize it, if the rear brake's control cable runs down the side of the top tube they already have the ability to control the rear brake.... just reach down and pull up on the cable.
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