I spent the last couple of days working on an outrigger wheel so I could quantify exactly how much cornering force is required to flip this thing over. I also added a home made g-meter which consisted of a weight taped to a sliding sleeve over a rod (shown in the photo below). The sleeve is held back by a small elastic band. When I make a left hand turn, centrifugal force pulls the weight attached to the sleeve in the opposite direction. Also wound around the rod is a green wire which is pushed down the rod by the sleeve to mark the extent to which the sleeve was pulled.
What I discovered was that I could reach a speed of about 24 kph doing the tightest radius left hand turn possible before the outside wheel (right wheel) lifted off the ground. The turning radius was small enough to do a full circle on our cul-de-sac which is probably 35 to 40 feet in diameter. This means that I can take a hard right hand corner (hard meaning a turn to the fullest extent of the steering bar and corner like a T intersection) at 24 kph and not flip over. I seriously doubt I could do that on my Kett trike and survive and I know I can't do that on the M5 lowracer!
This still doesn't mean I can turn a moderate corner doing 60 kph down a mountain pass like I can on my road bike, but at least I have some feel for when the inside wheel starts to lose traction. My biggest concern regarding higher speed stability is at those speeds, my turns have much less lean - therefore much less weight shift to the inside of the turn which makes everything more stable.
I can see the need to find a nice long, empty stretch of road somewhere and try to ramp the speed up to 40 or 50, then do some turns to get a feel for how sharp a turn I can do safely.
I'm not as concerned about the actual stability of the trike during high speed turns as I am about having a feel for the limitations. The trans Canada record is not going to be broken by a vehicle that can take a sharp turn doing 50 kph - that's NOT what this is about. This is about the EFFICIENT application of power to produce speed over many, many days and many, many miles. An occasional reduction in effort to a SAFE speed during downhill turning conditions will mean energy conservation for times when it is safe to push harder. At the end of the day (literally) x amount of watts output will equal x miles covered.
As far as the home-made g-meter goes, I might invest in a digital meter... It would be good to know the exact g's required to cause a flip (somewhere between .5 and .75 I think), but there are other factors involved that a g-meter can't take into consideration. Like - how much lean there is into the turn. I can turn sharper and faster at slower speeds because I lean more. At high speeds, there is barely any lean at all and therefore barely any weight shift. The g's required to flip the trike over are much less because there is more weight at the outside of the turn.
I think next on the agenda is to get that second brake on, get my axle collars in, and re-design the steering bar.
Two Dew LIST:
1. Buy and install right brake
2. Invent new cable tensioner to allow more steering bar turn radius3. Add front derailleur
4. Order 20mm axle bolts for the rear wheels (I'm using 1/2 inch now which isn't right)5. Design and machine 2 seat mounts out of aluminum to replace current steel ones (e-machineshop.com) LATER.
6. Design and machine 2 steering tensioners out of alum to replace LATER
7. Order a new front wheel! (Helen is kind of upset that I am user her Zipp race wheel!)
8. Start work on the first fairing
9. Invent steering stiffener10. Add larger chain ring
and modify chain stays12. Fabricate new steering bar (aluminum or composite?) or rework existing
11. Make clamp-on out riggers and try to flip it (changed to#25)
13. Lathe an aluminum collar for .5" hub axles (Ben E. said he'd do it for me).
14. Design and build a trainer to fit mag trainer (donated by Michael Hoenig).
15. Replace steel cables with Kevlar (maybe not - I think the flex of steel is good....)
16. Crotch guard / fender
17. Narrow chain stays to allow foot to clear
18. fix derailleur
19. crank hitting chain stay
20. chain stay frame flex?
21. Narrow, high density foam for seat
22. Make front quick release safety23. Change steer cable sheaves to Pete Heals idea
24. Add missing and new webs26. Firm up relationship with a charity (Helen???)
25. Add a g-meter and quantify turning g's at flippage threshold. (add outriggers)
27. Find a PR person
|TOTAL distance on TCR1|
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