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-   -   Converting from USS to OSS Superman-style (http://www.bikeforums.net/recumbent/570704-converting-uss-oss-superman-style.html)

yangmusa 08-05-09 02:10 PM

Converting from USS to OSS Superman-style
 
I recently wrote about my experiences testing some high racers. While I really loved the bikes I tested, I think I've decided that I can't quite justify the upgrade (yet). But I very much liked the superman-style open cockpit setup and have been thinking about ways to convert my bike.

As you can see from this picture, my bike has a fairly short wheelbase and the fork stem is fairly close to the seat in relation to my legs.

I've been thinking of getting a RANS Flip-It, stem (or this stem) and adjustable open cockpit handlebars.

So my questions are:
  1. Can the Flip-It be locked at any angle?
  2. Do you think the handlebars will need to be too far ahead of the steering column for this to work?
  3. Any better solutions?

I suppose it would be much easier to convert to "praying hamster" style bars. I had these on my previous bike and found them to be ok - quite aero and good bike control. However, I found that I tended to very very sweaty armpits with that closed position - and based on my brief test rides it seems like open cockpit would not have the same problem.

jeffh129 08-05-09 02:32 PM

If you do follow through with the conversion check out the flipit and bars here

http://www.terracycle.com/

Better quality than Rans.

Actually talk to the folks at Terracycle. They can probably answer
your questions. You may want to e mail them that photo first. They are good people. They'll help you out.

Let us know how it goes.

yangmusa 08-05-09 02:38 PM

Quote:

Originally Posted by jeffh129 (Post 9426920)
http://www.terracycle.com/
Better quality than Rans.

It had better be - there's quite a cost differential too...

Quote:

Originally Posted by jeffh129 (Post 9426920)
Actually talk to the folks at Terracycle. They can probably answer
your questions. You may want to e mail them that photo first. They are good people. They'll help you out.

Good idea. Their knowledge might make the additional cost worth it.

PaPa 08-05-09 06:01 PM

The potential problem here, is whether or not your revised grip location will fall rearward of the steering axis (the red line), and by how far. And, whether or not you can tolerate the reach. Ideally, 4" (101mm) to 6" (152mm) of positive (aft of steering axis) tiller would be nice. Otherwise the bike's steering will feel overly sensitive and self-centering attributes will be reduced. This was one of the problems with the 'nervous' Sun Speedster - zero or negative tiller, depending on the rider.

http://a.imagehost.org/0224/IMG_4171a.jpg

yangmusa 08-05-09 06:08 PM

Quote:

Originally Posted by PaPa (Post 9428115)
The potential problem here, is whether or not your revised grip location will fall rearward of the steering axis (the red line), and by how far.

Oh, my hands will be at least 5" forward of the line... The open cockpit setup is intended to be with arms more or less straight out in front, right? I think it would be quite cramped if my arms were to be behind the steering axis.

Quote:

Originally Posted by PaPa (Post 9428115)
Ideally, 4" (101mm) to 6" (152mm) of positive (aft of steering axis) tiller would be nice. Otherwise the bike's steering will feel overly sensitive and self-centering attributes will be reduced. This was one of the problems with the 'nervous' Sun Speedster - zero or negative tiller, depending on the rider.

That very interesting. On upright bikes, especially road bikes, the grip is over very far forward of the steering axis. My impression from riding lots of different upright bikes is that it increases stability. But of course recumbents are different, and so it doesn't surprise me that the dynamics should be different.

Hmmm, maybe the lesson from all this is that my bike's geometry just wasn't designed in a way that will accept open cockpit handlebars.

PaPa 08-05-09 06:16 PM

Quote:

Originally Posted by yangmusa (Post 9428202)
Oh, my hands will be at least 5" forward of the line...

Not good - I can assure you, you won't like the handling with that much negative tiller.



Quote:

Originally Posted by yangmusa (Post 9428202)
That very interesting. On upright bikes, especially road bikes, the grip is over very far forward of the steering axis. My impression from riding lots of different upright bikes is that it increases stability. But of course recumbents are different, and so it doesn't surprise me that the dynamics should be different.

On an upright, the rider is usually weighting and pushing forward on the grips. But when seated on most recumbents, the weight of the arms are effectively pulling the grips rearward - just the opposite.

PaPa 08-05-09 06:55 PM

Quote:

Originally Posted by yangmusa (Post 9428202)
Hmmm, maybe the lesson from all this is that my bike's geometry just wasn't designed in a way that will accept open cockpit handlebars.

Correct. Because of two issues:

1.) the wheelbase is too short. (this places the head tube (steering axis) too close to the rider's shoulders, inhibiting or eliminating the use of positive tiller).

2.) the head tube angle is too shallow. (again, placing the steering axis too close to the rider's shoulders).

yangmusa 08-05-09 10:52 PM

Ah well. When it comes down to it, I rather like that nobody can work out how my bike steers :D

Now they'll stay in the dark...

PaPa 08-05-09 11:54 PM

http://a.imagehost.org/0741/IMG_4171b.jpg

Not mine - a Google find.

http://www.bikejournal.com/images/Ac...ith%20Bags.JPG

yangmusa 08-06-09 12:03 AM

I'm not very keen on the look of the Actionbent OSS handlebars. Looks-wise, I had been hoping to achieve something more like this:

http://www.hpvelotechnik.de/images/p...erad_mitzi.jpg

I think I'll stick to USS for now. I might reconsider praying hamster, as Actionbent has done that too and I used to have one of these and suppose I could live with that setup again.

Otherwise I'll aim to ride more and worry less :thumb:

jeffh129 08-06-09 09:58 AM

Boy, I don't know. The OSS on the Speedmachine looks very uncomfortable. Take a look at the Bacchetta Giro 20 or the Giro 26. That's what you'd need.

yangmusa 08-06-09 10:41 AM

Quote:

Originally Posted by jeffh129 (Post 9431950)
Boy, I don't know. The OSS on the Speedmachine looks very uncomfortable. Take a look at the Bacchetta Giro 20 or the Giro 26. That's what you'd need.

Agreed, the Bacchetta system looks ok too. But if you look at the relationship between seat, steering axis and hand position, you will see that PaPa is right - it won't work on my bike because my seat and steering axis are too close together.

jeffh129 08-06-09 01:57 PM

I didn't mean an upgrade to your current bent.....I meant a whole NEW Bacchetta :)

yangmusa 08-06-09 01:59 PM

Quote:

Originally Posted by jeffh129 (Post 9433878)
I didn't mean an upgrade to your current bent.....I meant a whole NEW Bacchetta :)

He he. The Giro 26 is one of the highracers I've tried, and I'd have to say I was quite impressed...


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