May 3

May 3, 2005

I'm the one on the left:

Argh!!! I need help!

I was going to put together a nice big post with a bunch of background information on this most recent design, but I'm having trouble and would appreciate some advice from those who have more experience with lowracer steering geometries and/or streamliners.

Here is the prototype:

It's basically a plywood sandwich board cut to the exact shape of the eventual fairing. This prototype needed to be reinforced with chromo tubing, but the 'production' model will be carbon fiber and won't require any additional metal structure.

The basic idea is to create a very strong frame by utilizing sandwich board technology consisting of carbon fiber layers over a stiff honeycomb core. The shape should then be simply cut out of the square board and components would bolt into place just like I've done with the plywood prototype.

The carbon fiber sandwich frame would be strong enough to provide crash protection and could include horizontal members that also follow the fairing shape. The advantage to this approach is the fairing itself does not need to provide any crash protection, and can be extremely thin and light weight - in fact, it could be vacuum formed out of thin plastic and could be considered somewhat disposable.

Currently, vision is by camera - the monitor is mounted on the flat area of the plywood frame that is directly in front of the riders face. I know, I know - before you start sending me emails about the applicability of viewing through a camera for a long distance endurance race, I am planning to make the top part of the frame removable some method of lifting the seat up for head-out or canopy viewing. To start with, I'm keeping it as simple as I can - and I am looking forward to experiencing exactly what it's like viewing a LCD monitor wired to an external miniature video camera.

The front headtube is completely vertical (no angle) with a negative rake and about 2 inches of trail on a 650 wheel. I've tried headtube angle before and it seems to work just fine - in fact I have a bunch of research by a few individuals who found that recumbents steer best with this type of steering geometry (Mike Burrows, etc).

The reason for the odd headtube angle is so I can put my intermediate drive further forward which allows my legs to pass without any interference. This position also allows me to route the chain from the cranks chain ring directly to the intermediary gear without needing any pulleys to move the chain to allow the front wheel to turn.

The FWD drive system itself seems to work just fine - I can turn the front wheel left and right quite a bit - probably as much as the M5 lowracer.

The steering is a remote linkage - like this:

The problem is, I can't ride the friggin thing!!!! And that's where I need some advice.

At first, I was able to make it down the street - barely and very wobbly. It occurred to me that my steering was BACKWARDS - but this is kind of confusing.... When I am lying back and the steering bar is above me, when I turn the bars clockwise, you would expect to initiate a right hand turn. Well, as you can see in the above photo, a clockwise turn (remember, I'm UNDER that steering bar) would produce a LEFT hand turn.

So, I reversed the steering linkage like so:

But it was WORSE!!!! I couldn't even get down the drive way. So I switched it back to the way it was, and had better luck. Why???? This makes no sense at all! I think it has something to do with the fact that I'm basically upside down. When I normally steer anything, I am sitting upright and making clockwise motions for right hand turns. Because I am lying down and the steering bar is basically above my head, something goes haywire in my brain and I can't seem to balance the bike at all.

I suppose the actual 'action' my body is used to making to produce a left hand turn is my left arm contracting and my right arm extending - right? Imagine that for a second and I think it applies to driving a car, an upright bike or even most recumbents. In fact, the M5 lowracer has tiller steering and it would be the same thing - I push out with my right arm to turn left. That's probably the reason why my brain preferred the reverse steering - because even when upside down, if I push out with my right arm, it would be pushing the front wheel to the left producing a left turn.

OK - but that isn't the real issue here - the problem is that I just can't even get the thing down the street without crashing a hundred times and I don't know why and could use some input from you. Here are some possible reasons:

1. Like the M5 lowracer, due to the reduced front wheel turning radius, some speed is required in order for small steering inputs to balance and steer the bike. When starting off from a stand still, it is very difficult to get the bike up to a decent speed without falling over first - mostly because it is so heavy and accelerates very slowly. I know for a fact that most streamliners require a running push start in order to get them up to a high enough speed that they can be balanced and steered with small steering movements. That 'could' be the issue here I guess, but it probably has as much steering radius as the M5, and the M5 can be started without any running pushes, so....

2. Some weirdness with the weight and weight distribution. This beast is probably 70 pounds and I would say the majority of it is directly over the front wheel. However, most streamliners weigh about the same and they can be ridden.

3. The headtube angle, trail and rake are wrong. I don't think this is the issue because I have done this before with a smaller wheel and it handled almost exactly like the M5 lowracer. But I don't know...

Help?


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