Learn to Ride a Bike

[RoninFrog]

Can you ride a bike?

I'm sick of seeing "motorcycles" that are really a big hunk of reaction wheels with some rover wheels stuck on the bottom.  Bikes in real life don't have reaction wheels, and they work great!  So I made a bicycle without reaction wheels.  Here's the challenge:

Try to ride this little bronco: http://kerbalx.com/crafts/67006.  You may edit the action groups.

Simple!  Can you ride a bike in KSP?  That's all!  Then post a video/screenshots showing what happened.  This challenge isn't supposed to be super hard or competitive.

Biker Census:

Spoiler

@RoninFrog 

Spoiler

 

 

 

A couple tips for best results:

•  Motor RPM between 130 and 150
•  Servo Torque Limit between 6 and 8 (higher numbers give more control but less stability)
• Throttle just above the first white notch

[The bike has been updated in case you are confused about the comments below.]

Edited January 22, 2021 by RoninFrog

[Kerbart]

Part of the problem is that wheels in KSP don't have proper angular momentum and the gyroscopic reactions that come with it and that are very helpful in keeping a bike upright when it is in motion.

[Misguided Kerbal]

That's nice, and I'll definitely give it a try. But I think the main problem is that Kerbals can't tilt and help you lean and etc, etc. Therefore, the reaction wheels act as the Kerbal leaning.

[Superfluous J]

9 minutes ago, Kerbart said:

Part of the problem is that wheels in KSP don't have proper angular momentum and the gyroscopic reactions that come with it and that are very helpful in keeping a bike upright when it is in motion.

AKA "Real bikes actually DO have reaction wheels"

[RoninFrog]

17 minutes ago, Kerbart said:

Part of the problem is that wheels in KSP don't have proper angular momentum and the gyroscopic reactions that come with it and that are very helpful in keeping a bike upright when it is in motion.

 

7 minutes ago, Superfluous J said:

AKA "Real bikes actually DO have reaction wheels"

 

According to this video, gyroscopic reactions and angular momentum aren't much of a factor at all for bikes.  It's all about the steering of the wheels.

 

Edited January 21, 2021 by RoninFrog

[sturmhauke]

4 hours ago, RoninFrog said:

According to this video, gyroscopic reactions and angular momentum aren't much of a factor at all for bikes.  It's all about the steering of the wheels.

I don't think that's what he's saying. Rather, the gyroscopic action of the wheels is only part of the answer. There's also the wheel trail, mass distribution, and overall geometry of the frame to consider. Your basic usable bicycle has these traits:

1. The gyroscopic action tends to make the bike lean into the turn, which helps the bike get its wheels back under itself.
2. The steering wheel (normally the front wheel) has positive trail - i.e., the steering axis intersects the ground in front of the wheel's contact point with the ground.
3. The distance from the steering control point to the steering wheel is shorter than the distance from the control point to the fixed wheel.
4. The center of mass is closer to the fixed wheel.

A bike design lacking in one of these traits can make up for it by improving the others. But a bike lacking all of them will fall over. Of course, there's still the question of whether KSP's physics simulation is good enough to allow a realistic-ish bicycle given that it doesn't really model gyroscopic effects.

[RealKerbal3x]

1 minute ago, sturmhauke said:

I don't think that's what he's saying. Rather, the gyroscopic action of the wheels is only part of the answer. There's also the wheel trail, mass distribution, and overall geometry of the frame to consider. Your basic usable bicycle has these traits:

1. The gyroscopic action tends to make the bike lean into the turn, which helps the bike get its wheels back under itself.
2. The steering wheel (normally the front wheel) has positive trail - i.e., the steering axis intersects the ground in front of the wheel's contact point with the ground.
3. The distance from the steering control point to the steering wheel is shorter than the distance from the control point to the fixed wheel.
4. The center of mass is closer to the fixed wheel.

A bike design lacking in one of these traits can make up for it by improving the others. But a bike lacking all of them will fall over. Of course, there's still the question of whether KSP's physics simulation is good enough to allow a realistic-ish bicycle given that it doesn't really model gyroscopic effects.

I don't think gyroscopic effects are modelled for rover wheels, but they might be for BG motors. So you might be able to build your own wheels and make a more realistic bike that way.

[Kerbart]

16 hours ago, RoninFrog said:

According to this video, gyroscopic reactions and angular momentum aren't much of a factor at all for bikes.  It's all about the steering of the wheels.

The gyroscopic action of the wheels result in steering action towards the direction the bike is falling—it's a beautiful feedback mechanism.

[Bej Kerman]

What happens if you use BG rotors and grip pads instead of Squad's horrid excuse for wheels?

[sturmhauke]

2 hours ago, Bej Kerman said:

What happens if you use BG rotors and grip pads instead of Squad's horrid excuse for wheels?

Sounds like it's time to experiment.

[RoninFrog]

Awesome results today!  I built a bicycle using BG parts, and it is stable and steerable.

Spoiler

 

 

I also rode it out to the monolith:

Spoiler

 

I'll change the challenge to use the new bike.

[Klapaucius]

On 1/21/2021 at 9:45 PM, sturmhauke said:

I don't think that's what he's saying. Rather, the gyroscopic action of the wheels is only part of the answer. There's also the wheel trail, mass distribution, and overall geometry of the frame to consider. Your basic usable bicycle has these traits:

1. The gyroscopic action tends to make the bike lean into the turn, which helps the bike get its wheels back under itself.
2. The steering wheel (normally the front wheel) has positive trail - i.e., the steering axis intersects the ground in front of the wheel's contact point with the ground.
3. The distance from the steering control point to the steering wheel is shorter than the distance from the control point to the fixed wheel.
4. The center of mass is closer to the fixed wheel.

A bike design lacking in one of these traits can make up for it by improving the others. But a bike lacking all of them will fall over. Of course, there's still the question of whether KSP's physics simulation is good enough to allow a realistic-ish bicycle given that it doesn't really model gyroscopic effects.

I was surprised at how much our small adjustments that seem natural and unnoticed contribute to stability.  It is also interesting just how ingrained those actions are.  This video about a reverse handlebars bicycle demonstrates that.

 

 

[Pds314]

On 1/20/2021 at 8:08 PM, Kerbart said:

Part of the problem is that wheels in KSP don't have proper angular momentum and the gyroscopic reactions that come with it and that are very helpful in keeping a bike upright when it is in motion.

That's actually a very minor effect. Fork angle, fork caster, center of mass, and the balancing skill of the rider matter way more than any gyro effects of the wheels, and experiments have been done with bicycle-like vehicles that are designed not to produce any gyro effects and they are perfectly rideable.

On 1/22/2021 at 12:20 PM, Klapaucius said:

I was surprised at how much our small adjustments that seem natural and unnoticed contribute to stability.  It is also interesting just how ingrained those actions are.  This video about a reverse handlebars bicycle demonstrates that.

 

 

Yeah the trick to riding one of these is don't touch the handlebars. Don't look at the handlebars. Don't do anything with the handlebars. Most bikes don't require use of the handlebars to be ridden and can be controlled purely by balance, which this bike reacts to normally.

[Kerbart]

1 hour ago, Pds314 said:

That's actually a very minor effect. Fork angle, fork caster, center of mass, and the balancing skill of the rider matter way more than any gyro effects of the wheels, and experiments have been done with bicycle-like vehicles that are designed not to produce any gyro effects and they are perfectly rideable.

It does? Because a bicycle is perfectly capable of moving in a straight line and remaining stable without a rider. One of my classmates in high school had this trick where he'd jump off his bike while riding it, run alongside with it for any amount of time (well, within reason of being able to keep up with it) and jump back on. Funny as hell but the bike would roll along just fine without him.

[Pds314]

40 minutes ago, Kerbart said:

It does? Because a bicycle is perfectly capable of moving in a straight line and remaining stable without a rider. One of my classmates in high school had this trick where he'd jump off his bike while riding it, run alongside with it for any amount of time (well, within reason of being able to keep up with it) and jump back on. Funny as hell but the bike would roll along just fine without him.

Yeah it doesn't strictly require the rider to balance. But their inputs definitely help.

Edited February 7, 2021 by Pds314

[vyznev]

On 1/21/2021 at 11:16 PM, Bej Kerman said:

What happens if you use BG rotors and grip pads instead of Squad's horrid excuse for wheels?

Something like this.

Unfortunately, it seems that KSP 1.11 kind of broke that bike. I'm still hoping to find some way to fix it, but I haven't had much time to play with KSP lately. The major issue seems to be that rotor torque was nerfed, but that's easy enough to fix in the SPH by setting the rear wheel torque to 100%. But it seems that there was also some other change that somehow made the bike a lot less stable. It used to run nice and straight on flat ground in 1.10, with only minor and occasional course adjustments needed on hilly terrain. I could literally leave it running while I went to get a cup of coffee. But now the bike veers constantly to one side and is almost impossible to keep going straight for even a few seconds, making it only barely driveable.

[davidjimrd]

On 1/21/2021 at 7:44 AM, RoninFrog said:

Can you ride a bike?

I'm sick of seeing "motorcycles" that are really a big hunk of reaction wheels with some rover wheels stuck on the bottom.  Bikes in real life don't have reaction wheels, and they work great!  So I made a bicycle without reaction wheels.  Here's the challenge:

Try to ride this little bronco: http://kerbalx.com/crafts/67006.  You may edit the action groups.

Simple!  Can you ride a bike in KSP?  That's all!  Then post a video/screenshots showing what happened.  This challenge isn't supposed to be super hard or competitive.

Biker Census:

  Reveal hidden contents

@RoninFrog 

  Reveal hidden contents

 

 

 

A couple tips for best results:

•  Motor RPM between 130 and 150
•  Servo Torque Limit between 6 and 8 (higher numbers give more control but less stability)
• Throttle just above the first white notch

[The bike has been updated in case you are confused about the comments below.]

This is my dream! If i could fly one day!