JerseyJim
Guru
Have you seen what people spend on their bikes to gain 2 watts? Yeah I'm looking at you oversized pulley wheel.
I'll take "short lived 25 watts" for free any day.
Are you a pusher or puller?
- Thread starter JerseyJim
- Start date
I'll take "short lived 25 watts" for free any day.
bladderhead
Zen MBB Master
I push on the Grasshopper. I also did on the Silvio in the early days. It made the bike hard to steer. I learned to pull on the Silvio. I learned this very quickly. Pulling seems natural on the Silvio and S40, as pushing does on the Grasshopper.
You were looking at my Silvio which had a big cage and titanium jockey-wheels. Somewhere on the internet I read that the jockey-wheels are smaller than any of the cogs, so they spin faster and further. I did not notice any difference. If I want more watts I need to get new lungs.JerseyJim said:
JerseyJim
Guru
Yes, every so often we get a bicycle trend that's more akin to fashion than performance. I'm sure it makes a difference if your job is to ride time trials against other world class athletes and measure your time by the thousandth of a second. Otherwise It's kinda like 20" car rims in the 1990s. Those dubs were everywhere and on everything whether they were appropriate or not.
McWheels
Off the long run
Pulling only for me I think. I manage a light balancing pressure back toward me for each foot going forward.
I've tried putting a fist behind the handlebar so that I could only push, but I found it like trying to run with my arms 180 deg out of sync. As a foot goes forward, so the arm on that side wants to come back, which engages my core to keep the 2 braced against each other, just like running or walking.
I've tried putting a fist behind the handlebar so that I could only push, but I found it like trying to run with my arms 180 deg out of sync. As a foot goes forward, so the arm on that side wants to come back, which engages my core to keep the 2 braced against each other, just like running or walking.
joy
Well-Known Member
I am a puller, masher. Spinning just doesn’t seem to work for me. I am also a kayaker and the pulling motion with a paddle/foot peg pushing matches my riding technique. A kayaking friend couldn’t ride our stick bike, but got right on my Silvio and rode off. Same technique. Just do what works for your body.
benphyr
Guru-me-not
Ruminating on this topic. With respect to being able to push more than pull: We push forward with our legs and that is the largest force in play ranging very close to parallel to the direction of travel. The sideways component of that force that creates the torque involved in the steering input is quite small in comparison (probably low single digit %). This smaller force is the one that we are counteracting with our arms.
JerseyJim
Guru
Is it though? Is the force really that low? Maybe when you're already on the move and you're rolling already, but as soon as you look at the starting condition or a sprint, I think the force is higher.
You're right that in that I share the same experience where just cruising along there's just a little bit of pressure on my hands as I pedal, but when I accelerate that turning force seems to get a lot larger. To what degree that happens depends on where the bottom bracket is, which depends on your inseam.
To be fair, the pedaling dynamics are complex. Upright bikes aren't well understood and that's after over 100 years. Moving bottom bracket front wheel drive bikes...well you'd have to say it's even less well understood. It all merits further thought.
In the meantime, it sure is fun riding these bikes!
Vulcanelli
Member
As someone on the bottom of the learning curve having only a handful of rides on my first Cruzer (S40), I find I work harder riding this bike than on my upright. I ride clipped in and find it is easier to both push and pull in the reclined position than on my upright, so I do it more. I also think I am probably riding faster.
I like the bike, however it is a bit of white knuckle ride because I am not used to managing so much front-end weight. It feels like it wants to dive to one side or the other. I have to say I don’t daydream while riding this bike as I am very attentive to balancing the pedaling/steering dynamic. It feels like any small steering mistake will result in me having a sudden and intimate interview with the pavement.
I do get a lot of waves from other cyclists who have never seen anything like this bike.
I like the bike, however it is a bit of white knuckle ride because I am not used to managing so much front-end weight. It feels like it wants to dive to one side or the other. I have to say I don’t daydream while riding this bike as I am very attentive to balancing the pedaling/steering dynamic. It feels like any small steering mistake will result in me having a sudden and intimate interview with the pavement.
I do get a lot of waves from other cyclists who have never seen anything like this bike.
billyk
Guru
Remarkably, and possibly for the first time, I disagree with @benphyr ...
Sure, the largest force is exerted by the feet, but I don't think that's what we mean by "pushing". What other way is there to make the bike go?
The relevant distinction between pushing and pulling is really the difference between our bikes and traditional recumbents (TR).
On a TR you only get power like a leg press machine: between the seat back cupping your lower back and the pedals. That's pushing.
On a CB, we have another way to exert force on the pedals: between the handlebars ("pulling") and the feet. A CB can be ridden without a seat back ... Try this by inching your butt forward a bit and using your hands to pull your upper back off the seat. It's easy. Pure pulling.
That's "pulling" taken to the extreme. It's optional: a CB can be ridden with only pushing like a TR ... that's what riding no-hands is.
But pulling is really our advantage over TRs. It's our ability to engage the upper body that makes our bikes faster, especially uphill. It's much closer to a rowing machine than a leg press machine. I find myself doing this engagement whenever I'm working hard: uphill, digging in to make a traffic light, late to work, trying to catch someone in the bike trail, (escaping from a dog!). In those situations my arms are pulling my upper back away from the seat as I'm giving maximum pressure on the pedals.
As I said above, it's optional; we get to mix it up. I think we use pulling when we want more power, but relax and ride partly like a TR (" pushing") when we're just cruising.
That's my experience: 10 years on TRs, 9 on my various Q model CBs.
benphyr
Guru-me-not
Sorry @billyk , I don’t disagree with you,
but I did write my post poorly. My sole point with that whole paragraph was to say that the amount of push or pull with our arms is small compared with what our legs can put out so it is a good thing that the stabilizing amounts required from our arms are quite small.
Thereby allowing that when we sprint, climb, outrun dogs, etc. we can use almost all of our arm strength to increase the power that is hitting the pedals for that brief period before our arms give out.
Here’s an analogy. Walking along with one hand on the stem to steer and balance the bike beside you. The first situation requires the hand to steer and balance and the legs to support and balance the weight of the person.
Then add a bag full of heavy groceries in the other hand. The second scenario requires steer and balance plus extra to lift the groceries both in the arm lifting up and the leg pushing down against the ground to counteract the weight of the person plus the weight of the groceries. The legs and arms are both working harder (and the arms will give out first) with a resultant greater push (force) exerted on the ground.
@billyk I will attempt to write more clearly so as to agree/disagree more clearly.
JerseyJim
Guru
I think this sentiment is pretty common while climbing that learning curve. Some people take to it quicker than others, but there's no question that it takes time. I had no problem riding my T50 when I got it, but initially I found that I was really uncomfortable at a higher cadence - which was my normal cadence. When I say "uncomfortable" I mean I lacked the directional control and was kinda shaky over 70 rpm. Below that I was fine and I thought that I would never be able to spin on the Cruzbike. Turns out that I just needed some seat time and to build up those new neuro-muscular pathways to coordinate my arm and leg movements. Now I can spin over 100 rpm if I want to. You'll get there for sure. Keep at it.
JerseyJim
Guru
Actually I also refer to pushing with the arms as pushing and not just pressing back into the seat with from the pressure of the legs.
With MBB bikes you can counter the force of the legs with the arms by pushing, pulling, or both simultaneously. So you can sprint by pushing on the handlebars and not pull...Pull and not push...or push and pull. You'll get the same advantage but you'll be using different muscle groups depending on what you are doing and some muscle groups are stronger than others, depending on how you've conditioned them. That was one of the things I was curious about when I made the original post because pulling requires more back muscle, which is typically a weaker group than pushing, which involves more chest muscle. This was the observation of the study I linked to in an earlier post.
I think over time the pushing and pulling strength can be equal as the muscles involved are conditioned.
I'm also fascinated at how many different approaches and explanations there are about how people deal with a Cruzbike's pedaling dynamics.
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JerseyJim
Guru
BTW, I think I rode my Cruzbike for a month or so without cleats before clipping in. It just reduced the amount of things I had to deal with while I was getting used to the bike.
billyk
Guru
I don’t think this works.
You can counter pedal steer by pushing rhythmically on the handlebars, but that's a minor part of it. (And it feels weird; I've tried it as part of learning this bike years ago).
We're talking about getting more power on a CB by using the arms.
If you push on the bars, you will press your upper back into the seat. How would that direct more force to the pedals?
The point here is to give you that extra power by applying a force that strengthens what your feet are doing. Namely the force has to be directed forward. You can do that by pushing against the seat back (as in a TR), or on a CB you can do that by pulling with your hands (thus forcing the rest of your body - specifically your feet - forward).
I don't believe you can direct extra force to the pedals by pushing with your hands.
The force you can push into the pedal is limited py the strength and stability of your leg. You can push the pedal as hard as you can, just by bracing your back into the seat.
The bad thing about MBB is, that pedaling causes a steering input. You need to either counter that by also putting sideways force into your foot motion or accept it by riding a curvy line or you can stabilize the bottom bracket mith the handle bars. The Cruzbike videos tell you to stabilize by gently pushing the handlebar on the side opposite to the pedal you are pushing, but you can also pull the side of the pedal you are pushing. You can also use a sideways force in the handle bars. Or you can combine all these into a full circular concept. (As it is a rotation around the steering axis.)
Now the good thing about the MBB js that you can go one step ahead and overcompensate the steering input. That way you move the bottom braketninto your foot force. Butbthat can not increase force, only the distance, this force is applied at. So you can complete the stroke faster and get more RPM with the same force / torque, ergo more power. What forces you use to create the steering torque mattery maybe a bit in what part of the bike can brace you ste stiffest: The bike needs to brace two apposing forces, either between pedal and seat or between pedal and handle bars - Or a mix of both, all to the pedals and part to the seat, part to the handle bars. When pulling the bars, your leg pushing is also bracing for handle bar pulling, when handle bar pushing, your seat needs to brace pedal pushing and handle bar pushing. As the handle needs to get the same steering touque either way, I guess it is stressed about the same in both scenarios, but the seat gets additional force when pushing the handle bars and gets spared a bit when pulling the handle bars, so probebly less losses to flexing in seatband frame. But the larger difference should be biomechanical / ergonomic. Its about what muscles are more suited to the force they are supposed to create and if using multiple methods / muscles increases capability and efficiency. Pushing is only the arm and it braces against the seat. Pulling needs to brace against the pedal, so the whole body is involved. For stabilizing the handling, I'd guess pushing the bars is most efficient. But for adding power, we may again have the phenomenon, that the same force from a larger part of your body can produce more distance and therby more power.
And of course most powerful and stable on the seat would be to combine both, just as it is more powerful to pull one pedal while you push the other. Highest power nearly always comes with not the greatest efficiency. So I think for gentle cruising you can most efficiently just push legs and arms, for maximum power you should use everything available. (Phrased like that, it sounds obvious. )
The bad thing about MBB is, that pedaling causes a steering input. You need to either counter that by also putting sideways force into your foot motion or accept it by riding a curvy line or you can stabilize the bottom bracket mith the handle bars. The Cruzbike videos tell you to stabilize by gently pushing the handlebar on the side opposite to the pedal you are pushing, but you can also pull the side of the pedal you are pushing. You can also use a sideways force in the handle bars. Or you can combine all these into a full circular concept. (As it is a rotation around the steering axis.)
Now the good thing about the MBB js that you can go one step ahead and overcompensate the steering input. That way you move the bottom braketninto your foot force. Butbthat can not increase force, only the distance, this force is applied at. So you can complete the stroke faster and get more RPM with the same force / torque, ergo more power. What forces you use to create the steering torque mattery maybe a bit in what part of the bike can brace you ste stiffest: The bike needs to brace two apposing forces, either between pedal and seat or between pedal and handle bars - Or a mix of both, all to the pedals and part to the seat, part to the handle bars. When pulling the bars, your leg pushing is also bracing for handle bar pulling, when handle bar pushing, your seat needs to brace pedal pushing and handle bar pushing. As the handle needs to get the same steering touque either way, I guess it is stressed about the same in both scenarios, but the seat gets additional force when pushing the handle bars and gets spared a bit when pulling the handle bars, so probebly less losses to flexing in seatband frame. But the larger difference should be biomechanical / ergonomic. Its about what muscles are more suited to the force they are supposed to create and if using multiple methods / muscles increases capability and efficiency. Pushing is only the arm and it braces against the seat. Pulling needs to brace against the pedal, so the whole body is involved. For stabilizing the handling, I'd guess pushing the bars is most efficient. But for adding power, we may again have the phenomenon, that the same force from a larger part of your body can produce more distance and therby more power.
And of course most powerful and stable on the seat would be to combine both, just as it is more powerful to pull one pedal while you push the other. Highest power nearly always comes with not the greatest efficiency. So I think for gentle cruising you can most efficiently just push legs and arms, for maximum power you should use everything available. (Phrased like that, it sounds obvious.
)
JerseyJim
Guru
I don't see why you can't. It doesn't defy any laws of physics.
Push the pedal with your right foot. The left arm stabilizes. At minimum it acts as a rod, transferring force through the shoulder and back into the seat. If you drew the system on paper and represented the arm as a straight rod, then the limit of the stabilizing force is based on the compressive strength of the rod. If your leg was strong enough to break the rod, that'd be the limit of how much force you can put through the pedal. But it's not a straight rod. It's got a hinge at the elbow. This means you must use additional force to extend the arm and counter the leg force. By doing that you're adding force to the system. It's the same force you would use to do a bench press. With that force you could: A. Overcome the force of the right leg and start moving the steering in the direction of that leg or B. Push harder with the right leg until the forces are equal - a force greater than if the muscles extending the left arm were not fully engaged.
If you're adding force to the system through the arms, that increases the force the legs must put out to balance it, resulting in a net increase in propulsive force.
However we're not just talking about arms muscles when pushing. There's shoulder and chest muscles involved too.
If it's not possible to direct significant force with the upper body by pushing, then no one has ever bench pressed anything. While true that legs are nearly twice as strong as arms as evidenced by bench press and leg press world records, I would go back to the studies I referenced earlier about pulling and pushing strength. The conclusion was that for most people they are stronger in pushing than pulling, however muscle groups in the weaker activity can be conditioned to equal that in the stronger one.
Pushing works. Pulling works. Pushing and pulling work in concert.
Without stabilizing steering, your leg can already push with as much force as it can. (It just wastes a bit of distance by turning the steering.) You cannot add force to that from the other side. Whan doing squats, it does not matter, if the floor can withstand 200kg or 2000kg equivalent force. The floor will only ever push back as hard as you can push it with your feet. Equally when the pedal pushes back harder than your feet can, your leg gives and the pedal moves backwards. A static bottom bracket could push back way harder than you can with the handle bars of an MBB or than your legs can. Moving the bottom bracket can only add distance/speed, which multiplied with the force makes for more work/power. Similar to a longer crank: You use the same force over a longer distance. But with longer cranks you would need to move your feet faster, with an MBB the additional distance comes from the arms. So it rather gives the frequency-advantage of shorter cranks, without losing the torque-advantage of your real cranks.
(And now I will try going to sleep instead of cracking my brain with simulations of how an MBB interacts with non-round chainrings. I don't have much hope for that try.)
JerseyJim
Guru
Without stabilizing steering, when the pedal is pushed, the fork flops over and nothing usable is transmitted into the crank to produce forward motion. That's a bit more than wasting some distance by turning the steering. A MBB requires an equal and opposite countering force to prevent the front wheel from turning about the fork's axis of rotation. If one were to push the pedal with as much force as one can without countering that pedaling force the result would not look anything like riding a bicycle.
Indeed, metal or carbon fiber is stronger. Yes, a static bottom bracket does push back, or it wouldn't work to transmit any power. The same goes for a MBB. It needs a stabilizing force to counter the turning. That's not just the arms. When you follow the force path it goes through the arms, into the torso, into the seat/frame. Without a stabilizing force, you can't pedal. The crank falls away from the pushing foot across the centerline of the bike. If this system was a rigid frame like the static bottom bracket, the strength of the frame governs. However we brace with our bodies because we can add force with muscles. At minimum the force locks everything in place. At maximum the muscles can increase the force applied and the leg can push harder as a result.
As far as the analogy concerning squats, you are only talking about static force. The weight of 200kg is mass times gravity. If I want to move 200kg upward, I have to overcome gravity. That means I need to add force. More specifically, I need to accelerate that mass of 200kg in an opposite direction of gravity at a rate larger than gravity. That force will be F=ma and it will be larger than 200kg if I want to move it. Specifically the "a" acceleration, will be greater than the "g" acceleration due to gravity. The force required to move the 200kg, accelerate it upward, comes from my muscles.
If muscles could not add force to a system, then it would be impossible to lift anything because that would break the rules of physics. It would also be impossible to stabilize a MBB system.
"Moving Bottom Bracket" is a description of of the drivetrain configuration, it's not a description of how to pedal. Ideally, the bottom bracket moves as little as possible when pedaling. This requires a stabilizing force.
