Balance and Speed

[IndianaDave]

Cruzers
I'm a 30 day newbe and discovered a gem on my ride today.

The faster one goes, the more stable my Cruzbike becomes. All due to the gyroscope effect of the spinning wheels.

Simple physics ...

WHY I didn't think of this sooner ...

Hope this helps those who are new and still wobbling down the road.
ID

 

[Frito Bandito]

With these faster speeds also means having to look further ahead, plan an exit strategy earlier, and knowing that you have less time to react to keep the sunny side up
1 thing that has helped me is to think when riding by someone is to think "What is the absolute worse thing that person could do to cause an accident?" and ride accordingly.

 

[billyk]

All due to the gyroscope effect of the spinning wheels.

Certainly glad you're enjoying the bike.... but spinning wheels contribute almost nothing to stability. Any 4-year-old can easily balance one of those little scooters with 2-inch wheels. My guess is that you're just getting more skill and more confidence, which is indeed to be celebrated. It's you, not the wheels.

 

[LarryOz]

Certainly glad you're enjoying the bike.... but spinning wheels contribute almost nothing to stability. Any 4-year-old can easily balance one of those little scooters with 2-inch wheels. My guess is that you're just getting more skill and more confidence, which is indeed to be celebrated. It's you, not the wheels.

True - that is unless Dave is using these for his wheel set. - would be a first, but riding around on these for awhile and then going back to something lighter - well - just think of the sudden increase in speed and comfort!

 

[IndianaDave]

Wow ,,,
Appreciate and enjoy your thoughts on inertia and skill.

Ponder this ...
Next time you have your rear wheel off your bike, hold it with your hands on each side of the axle.

Really easy to manuver side to side or turn it, huh?

Now, spin the wheel as fast as you can and again hold it each side at the axle. As it spins, try to move it as if turning left or right.

Hard to do isn't it? At least, much more difficult than if it weren't spinning.

Notice how the wheel tries to react the opposite way you are trying to turn it?

Isn't that the gyroscope theory? Wouldn't that apply to riding faster, thus creating straight line stability?

I could be wrong, but my logic says, going faster creates greater stability.

Comments welcomed ...

Let's RIDE ... FASTER ...

 

[DavidCH]

If you want to practice your sprints... just imagine a dog running after you with big teeth.

If its a greyhound.... just give up gracefully

 

[DavidCH]

If you have rim brakes be aware the faster you go, the slower the braking.

If your name is Larry then you don't use the brakes.

 

[LarryOz]

Wow ,,,
Appreciate and enjoy your thoughts on inertia and skill.

Ponder this ...
Next time you have your rear wheel off your bike, hold it with your hands on each side of the axle.

Really easy to manuver side to side or turn it, huh?

Now, spin the wheel as fast as you can and again hold it each side at the axle. As it spins, try to move it as if turning left or right.

Hard to do isn't it? At least, much more difficult than if it weren't spinning.

Notice how the wheel tries to react the opposite way you are trying to turn it?

Isn't that the gyroscope theory? Wouldn't that apply to riding faster, thus creating straight line stability?

I could be wrong, but my logic says, going faster creates greater stability.

Comments welcomed ...

Let's RIDE ... FASTER ...

Dave, you are correct, the is some effect - it seems "like a lot" when you are holding the wheel with you hands and using your arms as the major force mechanism.
I think when you put the entire weight of the bike and your body into the equation there is probably more negligible effect of the "gyroscopic force" - although no one can deny it has to be there.
It even may help a little bit, but I think a large portion of what you are feeling when going faster is that you are probably more comfortable and are "at speed" instead of "trying to get up to speed" - which IMHO probably causes more instability by the shear application of more power during that time at a lower speed when smaller steering adjustment seem to be magnified.
i.e. Even with 100,000+ miles under my belt - I still wobble at times trying to keep the Vendetta upright when starting out of my driveway from a dead stop.
It is fun going fast - yeah and brakes are only used when absolutely necessary!
Looking forward to your future discoveries while riding.
Larry

 

[Jim Parker]

Interesting discussion. Here is an article about what keeps bicycles upright.
https://ezramagazine.cornell.edu/summer11/researchspotlight.html

It's the distribution of mass in relation to the steering axis that keeps a rolling bicycle balanced. Having the center of mass of the front steering assembly lower than that of the rear frame and forward of the steering axis makes any bicycle, including a Cruzbike, auto-correct and self-balance while rolling. This is why it's easier to ride no-hands on a Cruzbike with a low BB, because the bike is really good at self-balancing. I use a long chainstay on my V20 to raise the BB for aerodynamics, but it's a lot harder to ride no hands on it than my Q45.

 

[Mathew Fy]

I don't know if the V20 is susceptible to getting the dreaded speed wobble, but I haven't experienced it.
I felt stable when I hit 51 mph on this ride Saturday.
When I descend with high speed, I clamp my knees together to the boom - partly for increased stability, partly to reduce wind in the face.
But I wonder. Is CdA improved?

 

[DavidCH]

Haaaaa . Your cda greatly improves if you are bombing down a hill with both legs straight. This means you have to have one foot out of the clip. I prefer in all honesty to have both feet clipped in.

 

[IndianaDave]

Interesting discussion. Here is an article about what keeps bicycles upright.
https://ezramagazine.cornell.edu/summer11/researchspotlight.html

It's the distribution of mass in relation to the steering axis that keeps a rolling bicycle balanced. Having the center of mass of the front steering assembly lower than that of the rear frame and forward of the steering axis makes any bicycle, including a Cruzbike, auto-correct and self-balance while rolling. This is why it's easier to ride no-hands on a Cruzbike with a low BB, because the bike is really good at self-balancing. I use a long chainstay on my V20 to raise the BB for aerodynamics, but it's a lot harder to ride no hands on it than my Q45.

Mister Jim and all,

Great link centering on rotating wheels stability. Thank you.

And your experienced comments with BB placement is enlightening and educational.

FYI: During my 12 years as a custom diamond frame builder ( 102 PLANTENGA custom diamond frames), I relied on my research to keep the DF's trail at 1.75" no matter what headtube angle and fork rake were incorporated into the frames use.

Doing this 1.75" trail encouraged stability and little "flop" at most speeds with a DF.

A Cruzbike with its MBB has a tremendous amount of weight up front which, in my opinion, is nearly impossible to eliminate the rapid turning ( flop) along with tremendous oversteer.

If I were "redesigning" a Cruzbike's steering. I would decrease the headtube angle and increase the fork rake to create a geometric trail number of 1.75".

Not sure what would happen with the heavy MBB, but it might slow the steering and thus make a Cruzbike easier to control while learning to ride said.

That said ... usually it's what one gets used to and adapts to the designs idiosyncrasies.

Let's RIDE ...
Indiana Dave

 

[billyk]

Now, spin the wheel as fast as you can and again hold it each side at the axle. As it spins, try to move it as if turning left or right.

Hard to do isn't it? At least, much more difficult than if it weren't spinning.

Yup, as @LarryOz said, it's not nothing, but when you take into account the weight and forces on the whole bike-plus-rider system, it's relatively small.

Consider the forces when you lean into a turn. How hard would it be to stand next to a (stationary) rider leaning over that much and hold them up? Or what it would take to push that rider up a hill? Those are the kind of forces involved in riding, and they are much larger than the resistance you feel in moving a free-spinning wheel.

 

[ed72]

Wow ,,,
Appreciate and enjoy your thoughts on inertia and skill.

Ponder this ...
Next time you have your rear wheel off your bike, hold it with your hands on each side of the axle.

Really easy to manuver side to side or turn it, huh?

Now, spin the wheel as fast as you can and again hold it each side at the axle. As it spins, try to move it as if turning left or right.

Hard to do isn't it? At least, much more difficult than if it weren't spinning.

Notice how the wheel tries to react the opposite way you are trying to turn it?

Isn't that the gyroscope theory? Wouldn't that apply to riding faster, thus creating straight line stability?

I could be wrong, but my logic says, going faster creates greater stability.

Comments welcomed ...

Let's RIDE ... FASTER ...

you are wrong.

transfer functions that model of bike stability have many poles and zeros, the rotation of the wheel has a trivial contribution

once over the so-called critical velocity, bikes are inherently stable and self righting. hard to type right now but you can google recent research

 

[IndianaDave]

Cruzers
I'm going to stand by my seat of my pants experience ... increasing my speed, increased my stability.

Ride 5 mph and lean = BB and bike want to DIVE into the lean.

Ride 15 mph and lean = BB and bike are much more straight line stable.

Let's RIDE ...

 

[billyk]

Ride 5 mph and lean = BB and bike want to DIVE into the lean.

Ride 0 mph and fall directly over.

It's hard to balance at low speed on any bike because you don't have the ability to correct by steering to put the wheels under the lean, and the amount of steering required increases at low speed. Very slight steering adjustments work at high speed but aren't enough at low speed.

With the c.o.g. well above the wheel contact, staying upright requires constant active balancing. Aside from body English (which is limited for recumbent riders) the only thing we can do is steer so as to keep the wheels underneath us. That's less effective at low speed.

Think about balancing a tall stick on your finger. You do that by moving your hand so as to stay under the c.o.g.

 

[Randyc3]

Wow, looks like I purchased the right recumbent bike(16 days and approx 290 miles). What interesting discussion.
From my upright experience, push right on the handlebar, turn right due to force acting on the spinning wheel. My hypothesis is there are now 4 possible inputs to the front wheel: left/right via handlebar and left/right via your legs. For perfect inline riding all force inputs need to balance. And yes…..I am still wobbling. . Open to all comments ideas. Safe riding.

 

[DavidCH]

I am interested to know if there is less wobble on the new S40 compared to old. I sense that new headset will dampen that out.

 

[benphyr]

I don't know if the V20 is susceptible to getting the dreaded speed wobble, but I haven't experienced it.

My understanding is that speed wobble is when a vibration is magnified by harmonics of the frame or shall me part of the system. Our bodies are good at absorbing vibrations so since we have a large absorbing body attached via a large soft absorbing seat with not-locked arms on a not very symmetrical frame with extra mass and extra structure fortifying the steering axis with constantly changing input and legs that absorb shock too.

What I am trying to say is Cruzbikes rock. And decreased possibility of speed wobble is just one more reason why.

 

[LarryOz]

I am interested to know if there is less wobble on the new S40 compared to old. I sense that new headset will dampen that out.

Someone send me a pre-2o21 S40 and I will conduct the proper tests.