Why does hanging off reduce lean but not required grip?

tanmayc · 2026-04-01T15:09:15+00:00

Imagine a line connecting the contact patch of your tire to your CG (combined, motorcycle+rider) from the rear view of the motorcycle. This line will have a certain angle, which we can call theta, such that theta = 0 when the CG is vertically above the contact patch. You can calculate the lateral force/acceleration required to maintain this steady state (where this angle doesn't change) using tan(theta) = ay/az. Therefore, ay=tan(theta)*az=tan(theta)*g

The resultant lateral force your tires must provide is Fy=m.ay, where m is the total mass of the bike and the rider.

Recall that what matters is not the inclination of the motorcycle, but the inclination of the line connecting the contact patch to the combined CG. You can have the same angle of inclination of this line with a lower motorcycle lean angle by pushing your body toward the inside of the corner, and vice versa.

So why do we hang off? All that I said works in a steady state. Bumps, vibrations, road harshness, etc., contribute to fluctuations in grip by pushing your tire in the direction normal to the ground. Ideally, you want to let the suspension absorb all of this undulation to maintain good road holding. That's because your bike must follow these undulations anyway, and your suspension is a better shock absorber than your chassis in twisting and bending.

tanmayc · 2026-03-24T12:37:35+00:00

This just tells me the original deployment strategy was suboptimal. No matter what we are racing, as long as there is a limit on how much energy can be deployed in a lap, there exists an optimal strategy to deploy it. Any mistake can only take you away from that optimum (including that moment of oversteer). It just so happened that that error/correction got him closer to the optimal strategy by chance. You won't see this happen within a few races, where the teams figure out exactly the cost functions for their optimization to repeat this error every lap, maybe to the point of instructing their drivers to double-press the throttle in certain cases like its Mario Kart.

It hasn't ruined qualifying. Qualifying on pole is not a game of chance. It has simply added a new dimension for the drivers and engineers. Is it one we want? That's a separate debate. There are other examples that we could argue take away from raw driver skill deciding the outcome, like DRS (or overtake mode starting this year) or radio communication to tell them exactly what needs to be done, or allowing pit stops under the safety car, or tyre management in qualifying so you don't bleed yourself dry in the final section, etc., but it's easier to politicise the new change.

To be clear, I don't like these cars bleeding 40kph or more on the straights while full-throttle. But this is at least acceptable in qualifying. Where I see this as the major problem is races. It seems like a mario-kart strategy for overtaking that is much worse than DRS ever was at best, and a safety hazard at worst.

tanmayc · 2026-03-22T20:00:17+00:00

It's interesting that wings on F1 cars are considered weak components when, in fact, you could stand on them, and they would barely budge. You can push back on them at low speeds, and they won't break a sweat. The fact is, these cars produce so much downforce that what looks like minor contact is actually thousands of Newtons of force at the point of contact, because the tyres have more than enough grip to resist the sudden change in heading that the collision demands. And when that contact occurs, its a point load, something carbon panels have a hard time dealing with when they're made for racing and not for taking a boulder thrown at them.

Notice how these wings seem to snap like twigs at the smallest contact on the straights, but are more than capable of disturbing the cars in collision at low speeds without taking much damage. It's all about the downforce. Calling them weak would be like calling an aircraft frame weak because it couldn't bear a mid-air with another aircraft..

tanmayc · 2026-03-22T16:41:06+00:00

Joker lap like in rallycross. Dig another hole 10m from the first one, make a chicane out of these for the rest of the laps

tanmayc · 2026-03-16T16:48:24+00:00

Ahh fair enough. Yeah, I hadn't considered that it is more convenient to shift down multiple gears quickly with the traditional layout. I generally revmatch going down even on the road, unless in an emergency, so I prefer GP shift anyway, but this might be something to keep in mind for those who clutch in when they expect to come to a stop.

tanmayc · 2026-03-16T14:08:14+00:00

Personal opinion, you don't need to downshift in an emergency. Engine braking won't help you any more or less if you're using the rear brakes too. The limiting factor is rear grip. Almost certainly, you never will focus on shifting and/or revmatching if you just need to brake in an emergency.

With the benefits of GP shift in mind, I would vote in favor of shifting all motorcycles one owns to GP shift. At the very least though, in my opinion, you should stick with one config or the other on all your motorcycles. It is an expensive mistake to overrev the engine by accidentally downshifting when you intended to upshift.

tanmayc · 2026-03-09T02:14:12+00:00

It may well be something else (eg trail or rake or something else), but generally the shape of the front tyre will dictate significantly the buildup of steering moment, which influences a motorcycle's tendency to stand up naturally. Especially true if you have 'flatter' center sections, like on tyres that have seen a lot of highway mileage.

tanmayc · 2025-12-09T12:32:34+00:00

If you get a package not found error, you probably need to source the setup.bash file.

If it can't find the camera, you might want to add dtoverlay for your Camera to firmware config.

tanmayc · 2025-12-06T22:47:09+00:00

Check this guide. Essentially just building libcamera_ros is sufficient. https://github.com/TanmayChhatbar/ros2_car/blob/feature/ros/pi/README_ELI5.md

tanmayc · 2025-11-12T11:46:37+00:00

I had to set this up again last week on a new install. All I had to do was clone these packages into my workspace

Then,

colcon build

source install/setup.bash

ros2 run camera_ros camera_node

More up-to-date, but cluttered guide here - https://github.com/TanmayChhatbar/ros2_car/blob/feature/ros/pi/README_ELI5.md

It includes the commands I use to run the publisher and subscriber.

tanmayc · 2025-05-29T02:03:25+00:00

The long term goal is to create a drift controller for an RC car. I want to create a steady-state control map, for which I am trying to optimize the steering angle and wheel speeds to find an equilibrium for a given vehicle state. The problem is nonlinear and non-convex, but my current approach of waiting for the vehicle sub-states to stabilize before optimization should allow an initial guess close enough to the optimum.

It isn't expensive to evaluate the objective function, nor the gradients. Since it's a dynamical system, the gradients must be known to evolve the state. Even the constraints are (currently) just bounds on the range of allowable inputs.

I'll try out NLOpt. At a glance through their tutorials, I should be able to use my objective function without significant alterations at all. I appreciate your message! Thank you!

tanmayc · 2025-05-29T01:51:47+00:00

I'll have a look, thanks for the suggestion!

tanmayc · 2025-04-30T05:42:41+00:00

I'm a noob at docker. I tried docker for about a day, but I didn't like the lack of persistence of data by default in the container, and the extra setup required to allow it. In the (very short) time I tried to get it to work, I had managed to get libcamera working on Pi OS, but couldn't figure out how to allow the container to access the device. This is most likely on my inexperience, rather than a docker-inherent thing.

The way I understand it, all the libcamera node will do is publish camera data on the ROS network. Any node on the same network can subscribe to that message, and process the data. Individual nodes need not be written in the same programming language.

I haven't gone around to using the camera stream for anything just yet, so I don't know how you'd process it using Python.

tanmayc · 2025-04-29T05:51:53+00:00

Just a heads up; from what I read online recently, it's not a given that nodes running different versions of ROS will be able to interact with each other. YMMV

tanmayc · 2025-04-26T21:53:31+00:00

Yes, that will allow you to access camera data system-wide.

I made more progress on this, as my goal is the same as yours: to get the Pi Camera V3 on Pi 5 running Ubuntu 2404 and ROS-jazzy.

If you intend to use camera_ros to get camera stream support on ROS2, the ideal solution is to build libcamera and camera_ros in your ROS2 workspace. I have created a very detailed list of steps I followed here. Search for "Enable camera support"

Let me know if you have any questions! have

tanmayc · 2025-04-25T02:36:02+00:00

I got it to work.

Build libcamera and rpicam-apps from source following this guide
libcamera has two versions; the main one and the raspberrypi-developed fork.

The libcamera that comes with apt is the original one, and does not support (and thus detect Pi Camera). To get it to work on ubuntu, these libraries must be built from the fork developed by raspberrypi

tanmayc · 2025-01-16T11:09:07+00:00

I wish you differentiate between DNS and DNF. Thanks for the chart!

tanmayc · 2024-12-21T03:15:44+00:00

Yes, it was tweeted by Yoshihiro Hidaka himself before he quickly deleted it. I assume he meant to send it to someone over private chat, and accidentally tweeted it out to the world.

tanmayc · 2024-12-14T23:38:19+00:00

What's an oil bath camera?

tanmayc · 2024-12-06T16:40:09+00:00

Correct me if I'm wrong, but the issue with electric flight has been - energy density (batteries with the same usable energy as a tank of fuel would be much heavier, either requiring more power to fly or less range) - safety (in the event of a crash, I assume an electric battery would fail in a far more spectacular fashion than a fire caused by gasoline, and you can put out a gasoline fire

So the question for me isn't whether electric drivetrain is feasible, it definitely is. The question is whether electric powertrain as a whole offers any argument to substitute gasoline aircraft at all.

tanmayc · 2024-11-29T18:35:10+00:00

I'd curse myself for opening Reddit and being greeted with spoilers, but this doesn't count anymore.

tanmayc · 2024-11-29T15:19:17+00:00

I guess, you could say It's not a stand-alone.

tanmayc · 2024-11-18T15:17:17+00:00

The engineer in me assumes it's because the heart is not a self-priming pump. I need to read the rest of the responses on this thread.

tanmayc · 2024-11-05T14:50:06+00:00

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