Steering damper/stabilizer

[BikeGary]

Please post report when u have front flat at speed. My biggest fear.

I had one, there is a post in another thread about it. It was not pleasant. I totally lost control of the bike as it went into an uncontrollable wobble, then down on my side, ground off the teeth of the big sprocket, twisted my ankle, shredded my shorts, and rashed my arm and leg. The good news, no head injury! I ended up replacing the whole front crank assembly as it was cheaper than a new arm and chainring. I went from 25mph to 0 in about 30 ft. with at least 10 of it being on my side on the road.

Since then I have been sitting up at speed and trading speed for heat above 35mph to take it back down to 30+.

 

[Black Hawk Down]

I've > 5000 miles on my V20, and though I feel comfortable with the handling, I still feel that the bike is inherently unstable. Just because you can train your muscle memory to handle the bike doesn't mean it's a stable design. Consider a unicycle. People have ridden them around the world, but clearly they are an unstable design. I encourage new ideas that will make the design more stable. Either way, I'm sticking with Cruzebike.

 

[Balor]

I've > 5000 miles on my V20, and though I feel comfortable with the handling, I still feel that the bike is inherently unstable. Just because you can train your muscle memory to handle the bike doesn't mean it's a stable design. Consider a unicycle. People have ridden them around the world, but clearly they are an unstable design. I encourage new ideas that will make the design more stable. Either way, I'm sticking with Cruzebike.

Yea, my points exactly. Come to think about, neither unicycles or even best designed DF cycles are 'inherently stable'. Some DF bicycles indeed exhibit some self-stability under certain condition, but that goes out of the window when you add a rider to the mix. What matters is Goldilocks zone where parameters are just 'good enough' for stable handling under all conditions - preferably including a front tire blowout.
For some, that 'zone' include unicycle. For others, only upright Dutch roadsters... and, obviously, trikes.

Can you make an recumbent that is about as tame as a dutch roadster? I doubt that - even if you get geometry absolutely right, a reclined body position that severely limits your upper body input for balance mean that any sudden/drastic change in steering wheel traction will go uncorrected and down you go.
That is why recumbents, ALL recumbents, need wider, lower pressure and bombproof (preferably - tubeless/tubed but with good sealant) tires.

A geometry with much less flop, more trail, and/or steering dampers/stabilizers will help, too, especially on downhills where extremely precise control over handlebars is required.
But in some cases, only a cockpit where you can sit upright completely unimpeded will help - because you can than add body English to keep balance. As I understand, on V20, this is really hard because bars are in the way.
Going short cranks should allow you to add bars without reach (or even 'reverse reach' like I've done) should help immensely.

 

[dtseng]

In my younger days, I used to be a proficient hang glider pilot. Like bicycles, these devices are made to be inherently meta-stable and therefore require constant body input to operate. I realized that crash from the air was deadly, so I sold the glider and got out of it. Then I got into cycling which is much safer, provided I cycle on the bike path and don't go at high speed. Under such operating conditions, I feel that cruzbikes are really safe because both of my feet can instantly touch the ground. On a steep down hill, I would apply rear brake intermittently; even on a V20 with its handlebar far up front, I can always sit upright and both feet off the pedals, then, I feel the bike is a lot more stable than a typical DF road bike.

MBB bikes have front wheel flop problem. I would like to say that the wheel flop is not what it mentioned in the literature: flop factor = trail x sin(A) x cos(A), where A=head tube angle; this is based on the false assumption that the front tire touches the ground at single point. In reality, for larger wheel diameter and less air pressure in the tire, front tire makes contact with the ground at quite long patch, that would nullify 10 to 20mm of flop factor. In MBB bike, even with A = 90 degrees, front wheel flop is due to asymmetrical mass distribution with respect to the steering axis, i.e., crank, chain rings, chain, chain stays, and boom, etc. (edit: sorry, I mean the boom, the frontal section of the cruzbike type of steering column.)

 

[Balor]

and tiller, etc.

Nope, tiller actually serves as 'counterbalance' I think I've mentioned that VERY few people can ride conventional highracers w/o hands because their problem is reversed - tiller 'outweights' front wheel offset and hence the wheel 'flops' OUT of the turn under weight of the tiller, resulting in steering out of the turn and prompt fall. A self-stable bike needs to steering inside the turn... but again, there can be too much of a good thing

 

[Balor]

In reality, for larger wheel diameter and less air pressure in the tire, front tire makes contact with the ground at quite long patch, that would nullify 10 to 20mm of flop factor.

Hmm, that is interesting... but it would still invoke camber torque forces.

 

[Balor]

In MBB bike, even with A = 90 degrees, front wheel flop is due to asymmetrical mass distribution with respect to the steering axis, i.e., crank, chain rings, chain, chain stays, and tiller, etc.

Oh, and that would be 'flop into *lean*'. Like I said, to a point it is beneficial. Flop into TURN with 90 deg is zero when it comes to conventional and 'mbb-specific' flop. There is no growing 'lever' against gravity as the wheel is turned. Of course, the situation is more complex than that, because of the frame and rider that also act on the steering.

 

[Black Hawk Down]

Come to think about, neither unicycles or even best designed DF cycles are 'inherently stable'. Some DF bicycles indeed exhibit some self-stability under certain condition, but that goes out of the window when you add a rider to the mix. What matters is Goldilocks zone where parameters are just 'good enough' for stable handling under all conditions - preferably including a front tire blowout.

When I referred to "inherently unstable" I meant in comparison to normal DF bike stability. Not absolute stability like a trike. I would like to see the CruzBike design evolve to make the steering less sensitive. I feel I have to be completely on edge when going down a hill above, say 35-40 mph. One bump in the road may bring you down. I have not had a flat in the last 5k miles (thank you GaterSkins!), but I dread the day it happens and I hope it's not a sudden blowout on either tire. I did drop the bike going around a corner at 30 mph. Hit some road divots, and to avoid additional divots. A quick avoidance move dropped the bike on it's side and I slid down the road to a stop. The bike slid on the two quick release knobs, the handlebar edge and the carbon fiber seat pan. Very little damage to the bike (have to look for the scrapes) and no damage to me. I was able to hold myself up with the handle bars to keep from dragging on the road. My shorts did hit the road once causing a big tear in them but I was without a mark. When I came to a stop, I saw a car was coming up on me fast. I tried to wiggle out from under the bike, but I was trapped long enough for the car to come to a complete stop. Man it's hard to get out of the V when down on the ground. If the guy wasn't paying attention, I would have been road-kill. I think if I had handlebars like you, I would not have been able to hold myself away from the road and I'd have sustained significant road-rash.

 

[Balor]

I would like to see the CruzBike design evolve to make the steering less sensitive. I feel I have to be completely on edge when going down a hill above, say 35-40 mph. One bump in the road may bring you down.

Yup, that's what actually started my quest for 'better MBB handling' - my first MBB with more conventional angles felt absolutely the same, even worse I suspect because I had smaller trail and heavier front triangle.
My current one is still a beast when it comes to weight, but feels absolutely, totally rock stable even furiously pedalling at 45 mph. Given that S40 has more trail and more upright seat, I presume it is tamer than Vendetta (maybe by far).

As for the bars - that's a good point. Fortunately, I've never needed this type of 'defence' for now, but I think I may add some 'bumpers' to prevent damage to shifters...

 

[RojoRacing]

When I referred to "inherently unstable" I meant in comparison to normal DF bike stability. Not absolute stability like a trike. I would like to see the CruzBike design evolve to make the steering less sensitive. I feel I have to be completely on edge when going down a hill above, say 35-40 mph. One bump in the road may bring you down. I have not had a flat in the last 5k miles (thank you GaterSkins!), but I dread the day it happens and I hope it's not a sudden blowout on either tire. I did drop the bike going around a corner at 30 mph. Hit some road divots, and to avoid additional divots. A quick avoidance move dropped the bike on it's side and I slid down the road to a stop. The bike slid on the two quick release knobs, the handlebar edge and the carbon fiber seat pan. Very little damage to the bike (have to look for the scrapes) and no damage to me. I was able to hold myself up with the handle bars to keep from dragging on the road. My shorts did hit the road once causing a big tear in them but I was without a mark. When I came to a stop, I saw a car was coming up on me fast. I tried to wiggle out from under the bike, but I was trapped long enough for the car to come to a complete stop. Man it's hard to get out of the V when down on the ground. If the guy wasn't paying attention, I would have been road-kill. I think if I had handlebars like you, I would not have been able to hold myself away from the road and I'd have sustained significant road-rash.

What you are able to hit and still stay stable is a matter of perspective and skill I think. What you describe at 40mph is how I start to feel in the range of 50-60mph, and I've hit lumps in the road that have gotten me airborne at over 40 mph and all I can say is I was lucky to not crash. If I can see something just before I hit it I can stiffen my grip on the bars and boom so as to not be so destabilized but if I'm totally relaxed like I normally would be, there's no telling how the sudden force will toss the weight of my legs and disrupt my steering.

 

[Black Hawk Down]

What you are able to hit and still stay stable is a matter of perspective and skill I think. What you describe at 40mph is how I start to feel in the range of 50-60mph, and I've hit lumps in the road that have gotten me airborne at over 40 mph and all I can say is I was lucky to not crash. If I can see something just before I hit it I can stiffen my grip on the bars and boom so as to not be so destabilized but if I'm totally relaxed like I normally would be, there's no telling how the sudden force will toss the weight of my legs and disrupt my steering.

I agree with everything you said, but my point is that I would like to see a CruzBike where I don't need to develop the skill that you have. I may never be able to develop to that level. I would prefer to be able to ride a CruzBike with the kind of confidence that I have with my DF at higher speeds and bumpy roads. I don't expect this to happen. It's a dream, I have...

 

[RojoRacing]

I agree with everything you said, but my point is that I would like to see a CruzBike where I don't need to develop the skill that you have. I may never be able to develop to that level. I would prefer to be able to ride a CruzBike with the kind of confidence that I have with my DF at higher speeds and bumpy roads. I don't expect this to happen. It's a dream, I have...

sadly you can't have your cake and eat it too, as I'm sure you're aware. What you desire can be done and in fact already has but at the cost of other things like weight, cost or design simplicity. Oddly enough the act of balancing on a razors edge of stability while rolling along at speeds most would deem hazardous is what I find fun. I'd venture to say the V20 is the main cause for my reduced excitement while descending on my DF bike these days and it has nothing to due with speed ether since they are exactly the same speed. It's understandable that most riders who would choose to ride a recumbent aren't in the habit of risking their safety for cheap thrills.

 

[Balor]

I'd venture to say the V20 is the main cause for my reduced excitement while descending on my DF bike these days and it has nothing to due with speed ether since they are exactly the same speed. It's understandable that most riders who would choose to ride a recumbent aren't in the habit of risking their safety for cheap thrills.

Also a good point. Are you familiar with concept of 'flow'? You get maximum involvement (and enjoyment) in activity when 'challenge' level is about proportional to your skill - not too much, not too low. Too much - you get stressed (and may actually start to make mistakes). Too little - and you get bored. As for 'cheap' thrills... well, I don't think that bombing down a mountain at 60 mph qualify as a 'cheap' thrill .

But making an MBB that is as reclined as Vendetta and adding 'steeper angle' steering shorter with boom may result in too much tiller - been there, done that. Also, head tube gets into your line of vision.
I daresay Vendetta is already pretty good when it comes to geometry, and if you find yourself 'overly challenged' - there should be an option of steering damper/stabilzer as per thread title. They *do* work. Increasing trail is a double-edged sword, because it make slow speed handling less stable.

 

[bladderhead]

Can you make an recumbent that is about as tame as a dutch roadster?

Also, a DF has the amazing ability to catapult you over the handlebars so you can get a nice bite of the tarmac.

Jason says he stiffens his grip as he goes over bumps. Cruzbike front wheel is between two long levers - the bars and the BB. So it is immune to unscheduled steering. Do MTB people have wide bars for extra leverage? Cruzbike has lots of leverage. My Silvio has no steering effects when I hang shopping on the bars.

slow speed handling

You choose what you want. Does Jason need slow speed handling on the way down Mt Diablo?

 

[Balor]

Do MTB people have wide bars for extra leverage? Cruzbike has lots of leverage. My Silvio has no steering effects when I hang shopping on the bars.

First, DF has differential input, that provide much better damping. Second, muscles used there are much stronger, as compared to 'tiller steering' (hence, longer tiller cannot replace wider bars, even it is as long as those bars).
If you put it this way, than a tiller of two meters would make for excellent handling... I ensure you, it is not. 'Tiller effect' is very well-known... why, pray tell, LWBS have either remote steering or very slack angles + lots of offset?

Plus, it is "two levers" is when you can use your legs to steer. Great if you can, I'm about 3 years into MBBs and still cannot. "If it can be done, doesn't mean you can do it!"
Otherwise, this is like swinging a a knife (DF) vs swinging a sledgehammer (MBB). Which you have better control over? And absolutely need that control, because steering correction are, basically, 'swings' where you need to first accelerate than decelerate (and you want it done very precisely, lets you overcorrect and fall) all that mass, and rotational inertia mass times radius SQUARED. And dampers/springs (and trail) allow you to better damp this inertia, while flop makes it harder.

Does Jason need slow speed handling on the way down Mt Diablo?

Maybe. Maybe not. But we, lesser mortals, sure need it on our way up. Or walk. In clipless shoes. With traffic whizzing by. *shrugs*

 

[Balor]

Btw, if you are into martial arts, it is highly likely you'll take to any MBB right away

 

[Balor]

What you desire can be done and in fact already has but at the cost of other things like weight, cost or design simplicity.

Actually, nothing prevents you from having something like S40 with shorter boom/bit longer tiller/steering angle like 80 with zero offset. Kinda like Zimins's MBB:

I bet it would be stable enough for pretty much anyone... just not very fast . He did not make the RAAM in time, after all, but he is not a young man either.
Full suspension and 90deg steering angles are, actually, optional - like I said, you don't need *perfect*, you need just *good enough*. I'm clumsy, have bad circulation and operate in cycling-hostile environment, hence all this complexities (and, admittedly, all this tinkering is half the fun).

Plus, Cane Creek viscoset is like 80$, maintenance free, adjustable to a point and weights a fraction more than conventional one. Did anyone try it yet?

 

[bladderhead]

Well, I am no Hong Kong Phooey, but I can do no-hands on my Silvio. Never got anywhere near it on the Grasshopper.

 

[castlerobber]

Well, I am no Hong Kong Phooey, but I can do no-hands on my Silvio.

Me neither, LOL. But since I put the Thor seat on my S30, I can finally do no-hands for short distances.

 

[Balor]

Well, I am no Hong Kong Phooey, but I can do no-hands on my Silvio. Never got anywhere near it on the Grasshopper.

Yup, like I said, 'pure' tiller is bad from weight distribution standpoint, but so is too much weight in front of the steering axis. I can finally cost no-hands on my last prototype, and pedal a bit (and on a conventional MBB it took me a mount to even dream about taking *one* hand off the handlebars), but any *lean* results in overcorrection... my boom is relatively short (a bit over 30cm), but front end is really heavy. Once I lighten it up, things should improve greatly.