Tortola Roundtail – A bicycle frame with a twist

12 comments
By BikeRadar UK | Monday, Apr 11, 2011 11.05am

A Canadian inventor has unveiled a new bicycle frame design that he claims is dramatically more comfortable than a traditional double diamond layout while retaining the same lateral stiffness and pedaling efficiency.

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Lou Tortola's ROUNDTAIL replaces the seat tube and stays of a standard frame with twin hoops of tubing. The idea is that instead of the seatstays transferring impacts and road buzz straight to your posterior, they're dispersed by the shock-absorbing rings.

Constructed by US bike builder Paul Taylor, of Montana-based Taylor Bicycles, the first alloy frame was unveiled at this weekend's San Diego Custom Bicycle Show. Apparently titanium and carbon road frames will be available by the time of the Interbike trade show in September, along with mountain bike and hybrid versions.

Tortola cites finite element analysis results that show the design provides 10 times the vertical flex and over 60 times the shock absorption of a traditional frame. That sounds like an awful lot of up and down movement to us. He also reckons it'll provide aerodynamic advantages. The ROUNDTAIL is said to have passed rigorous fatigue and impact strength testing.

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User Comments

There are 12 comments on this post

Showing 1 - 12 of 12 comments

  • Bonkers. A bit like those snowflake spoke patterns though. Just use a fatter tyre, or thicker saddle. If the frame flexes that much, unless its made of steel, won't it have durability issues?

  • looks bloody heavy

  • Flex for comfort is fine, undamped rebound is not so fine...

  • At last we see something that's not a chosen-from-a-Taiwanese-catalogue-and-uninspiringly-decaled a la Contat, Planet-X, Ribble, etc. This is original.

    Would be good if people kept their conjecture on how it rides to themselves until they ride it. Or can show some data from their lab tests on it, do you guys have any of that? Exactly...STFU.

    People laughed at the Softride Beam, I did until I rode one and it was great. Then I got off and chuckled again, but it was a pretty good idea which rode sweetly.

  • I thought April Fools day was on the 1st!!!!

    Lol!

  • must be a late one, lol

  • That's one doodle that should have stayed in the sketchbook! Just because you can shouldn't mean you should..there's no reason why you couldn't engineer a composite to give a similar degree of resilience - this looks like a solution to which nobody's quite worked out the question.

  • Interesting concept, but I think no matter how well it rides it's just fugly and not many people would be seen dead on it.

    10x's the vertical compliance is likely @3mm's, thats how little standard frames move.

    And the undamped nature is likely worse than it being rigid, it'll absorb the impact force then spike it straight back into you.

    Your going to require enough flex in the downtube or top tube to allow for the circle to bulge at those points otherwise the welds to the steerer tube will fail.

    Hope there using a Alu with good flexibility otherwise expect failures, not a wise choice, Ti maybe, Carbon wouldn't give at all and be back to a normal bike.

  • Why stop at the rear forks why not go the whole hog and turn the front forks into a round shape to dampen the shock at the front of the bike.

    They aren't seriously going to make these bikes are they ?

    Are you sure this isn't a late april fools joke ?

  • The School of Benny Hill Design

  • Hi Guys, Steve from Tortola Roundtail here... Thanks for your comments... the bike as pictured weighs 17 pounds, and that's the first proto/concept rig. Here's a link to the Finite Element Analysis - http://roundtail.ca/index.php/main/benefits

    Many, many people at the San Diego show were completely taken awestruck by the design, and several wanted to by one right then and there... I personally can't wait to ride our 29'er mountain bike design, I think that's where the design will really shine.

    See you on the road or trail...

  • From Carol in Windsor.........

    I wish the naysayers could just jump on the RoundTail and take it for a ride. I had that opportunity and loved the bike. Very fast acceleration and a smooth, comfortable, effortless ride.

    I don't know anything about mechanics, compliance or flex. I just know when I was riding I didn't want to stop.

    The RoundTail was out and around town this weekend. It attracted a great deal of positive attention and interest.

    It truly is a beautiful bike and I can't wait to ride it again.

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