Peter Krause's Corner -- Virtual Classroom

[Skeen]

I think we said the same thing.

[Jon62]

Mike, I think the double peak on the brake curve is the issue you mentioned to me at the track, where I was inadvertantly "rebraking" as I heel / toed on the downshift...Definately need more practive to make that smoother...

I am not consciously aware of a "confidence tap" of the brakes, but it also doesnt mean I am not doing it...

Really appreciate the feed back so far...Many thanks

Lazy right foot indeed...Sheesh

[ProCoach]

Originally Posted by Jon62

Really appreciate the feed back so far...Many thanks

Lazy right foot indeed...Sheesh

Hey, that's "factory" (normal)!

[ProCoach]

"Deciphering Data," a basic cheat-sheet for analyzing three key performance measurements using simple X-Y graphs provided by most inexpensive GPS-based DAQ systems, is on the news stands now in the May issue of Grassroots Motorsports. And yes, the lateral cornering graph legend for the colors is wrong!

[TailWagger]

Utterly different topic. I've shredded the suede on my current steering wheel, an OMP 320mm and so its time to consider a new one. The current wheel has an oval profile (the rim material, the wheel itself is your standard circle).

Web searchs yield little worth looking at or thinking about when it comes to steering wheels and their selection, something, which I find a little strange given how important a role they play. So I figured I'd probe the cognoscenti around these parts to see if anyone has some subtle insight into selecting a wheel. Seating position and clearance issues aside, is bigger necessarily better when you're muscling around 255s with no power steering and a quick ratio rack? Any preference for oval versus round, thicker versus thinner, suede versus leather, flat versus dish? How big a factor is glove style (I used to have heavy leather Alpine Stars which dictated a suede wheel, but I've since gone to lighter, grippier fabric Pumas...maybe leather is fine now)? Is this all a matter of personal preference or is there any theory, again outside of basic positioning, around what works better? Opinions are great, but some reasoning and logic behind them is even more appreciated.

I'll illustrate one bit of logic that I've applied to this subject by stating that I'm now totally wed to having a stripe on the wheel. I used to think it was for idiots, but I've come to find that having the stripe improves lessons learned from watching in car video as you can get a good sense of steering lock when reviewing the tape. So while I dont find it useful in the least in real time, it is a requirement for analysis as far as I'm concerned.

Thoughts, lessons learned over the years?

[Astraist]

A bigger wheel diameter is easier to turn and more accurate, but will be harder in quick and large steering input, because of the long hand motion. A larger wheels keeps the hands further apart, which makes it's static grip along the straights less comfortable. A smaller diameter means less accuracy, especially in larger movements, but greater agility of turning and usually a more comfortable static grip.

The proper diameter should allow for comfortable grip, accuracy, but also allow for quick inputs. Look at how apart your elbows are. In some cars you just find the elbows pointing "away" from one another. This should be minimized.

Wheel thickness should allow to cup the wheel's outer diameter with the palms and wrap the fingers around the wheel, so that the fingertips protrude below the crossbrace, all without moving the wrist from it's neutral position. The palms should form an immediate line from the forearm.

Leather gloves usually work best with stock steering wheels, usually made of bakelite. Suede wheels work better with the professional racing gloves.

After these adjustments, and the full exploitations of the seat, steering and pedal adjustments, ensure proper distance and angle relative to the wheel by stretching one hand forward to the top of the wheel (12 O'Clock). The proper distance in relation to racing is when the wrist can be placed flat over the top of the wheel.

I stress that the wrist needs to be able to rest over the wheel, and not just "touch" the face of the wheel. You should be able to do this without applying force or fully outstretching the arms, and while pushing the scapulae (shoulder-blades) back into the seat and not having to lean them forward. In the 9 to 3 grip the elbow angle should be about 100-90 degrees. The palms should be just slightly (2 cm) below shoulder height.

I find the subjects of driving position to be crucial for good driving. I know professional racers that would spend a day's worth of practice sessions on getting it just right: Starting with taking accurate measurements of height and length/proportions of the body, hands, legs and neck. They than fit the right seat and make the initial adjustments, go for a ride and readjust according to feel. And remember the priority: you first adjust the seat, than adjust the steering and than adjust the pedals.

[brkntrxn]

Wow, I actually agree with everything that Astraist stated in the post above.


-Kevin

[Astraist]

Is this a new beginning, Kevin? Why, I thought I could bring peace to the middle-east before I could bring it here.

[TailWagger]

Originally Posted by Astraist

I stress that the wrist needs to be able to rest over the wheel, and not just "touch" the face of the wheel...

I find the subjects of driving position to be crucial for good driving....

TW- "Seating position and clearance issues aside..."
"Is this all a matter of personal preference or is there any theory, again outside of basic positioning"

But lets take your response around seating position as illustrative of where I'd like to get to. I'm not looking for a dictum, I'm looking for theory and principle as guides for making a decision. So lets have a parable.

Numerous year ago, as a professional musician, I taught classical guitar. Conventional wisdom at least at that time, dictated that the right hand position be perpendicular to the strings in both dimensions. Why? Honestly, no one really ever told you and I suspect most never understood or ever considered the why.

To advance, its always the WHY that's most important thing to understand as what we do should always be an outcome of why we do it. With guitar playing the conventional dictum of hand positioning is predicated on an unstated assumption that when holding ones hand flat, the player's thumb extends to the first joint of the forefinger. Grab any ten people and what you'll find is that the ratio of the length of thumb to fingers is all over the map. For seven out of the ten, the stated position is impossible as their thumb cant actually reach the strings. The conventional wisdom was derived from the playing of Segovia, the modern father of the art, who just was happened to have thick pudgy fingers with a thumb that met the above requirements. And if your one of the unlucky seven or eight, if what you do is try to follow the convention wisdom and contort your hand into the "correct" position, you're utterly screwed.

But there IS principle that underlies the dictum. The reason is that addressing the string for plucking perpendicularly allows the purest strike, imparting the most energy with the least generation of unwanted artifacts. Or more simply, its enable you to maximize both volume and tone. Of equal importance, and this is, BTW, 100% analogous to reasoning behind race seating position, it is the large muscles that we want to be in control of the motion keeping the fingertips free to handle the critical task of feedback necessary for dealing with the subtitles. Addressing the strings vertically promotes initiating the strike from the larger muscles in the hand, not the smallish ones near the finger tips. By knowing and understanding the thinking behind the why, we can as our individual circumstances vary we can alter the 'what' to achieve the actual goal.

So responding to your thought on seating position. I happen to be 5' 6'. Trouble is I have the lower body of someone 5' 2" and the upper body of someone 5' 9". Gather any group of people, and just like the observation around thumbs above and you find all shapes and sizes. When I teach seating positioning, guitar playing or golf swings, I try never to talk about where any particular body part has to be and when. And in this case, the goal is that we'd like the larger muscles to do the work so that we keep the hands relaxed so that the fingers are free to be sense organs rather than vise grips. That's the why behind wrists over lay the steering wheel. What ever gets that done is likely the correct approach for that individual. To win the prize you have to first truly know what the prize is to be able to achieve it.

All a very long winded, but hopefully illustrative way, of trying to get across where I'd like to us to get to. What is the essence of how we "play" the wheel and how might varying its characteristics can effect our "tone and volume". I'm not looking for a prescription, but a set of principles to apply. Your first paragraph is utterly on point and I think there is something to be explored further there.

A bigger wheel diameter is easier to turn and more accurate, but will be harder in quick and large steering input, because of the long hand motion. A larger wheels keeps the hands further apart, which makes it's static grip along the straights less comfortable. A smaller diameter means less accuracy, especially in larger movements, but greater agility of turning and usually a more comfortable static grip.

This inspires me to wonder if there isn't some "golden mechanical ratio" for non-power systems that we'd like to achieve. Now lest you think me hypocritical for being desirous of a formula, its not really the formula I'm interested in. Its an understanding of all the factors that might play into, how varying each effects the outcome and the reasoning behind declaring a particular ratio as "golden" if such a thing could be done.

Sadly, I'm not mechanical engineer but I think it would be fascinating if someone in the audience or one of their acquaintances could run the general calculations to help us understand the mechanical effect of larger versus smaller steering wheel perhaps as a formula expressing inch pounds of effort for a degrees of deflection. Obviously steering ratio is a factor, castor or tire width/load perhaps? This whole thing feels akin to select transmission ratios. There is no one answer, but in the end we look at a series of factors, balance them out against the tracks we're running and the corner speeds we expect. Maybe this this far too many words spilt for a $250 item, but I hate simply taking things for granted until I know why I should.

[Astraist]

Warning, intense tech-talk below. If you are easily offended by tiring technical details, do not read.

I wouldn't say I was talking about the seating position per se. I left all the subjects of seat, pedal and height positioning aside and referred only to the subject of steering. You might as well refer to this as a "disclaimer." I feel obligated to mention those things when I write online.

The reason for the "formula" of distance, where the wrist is placed over the wheel, is simple: It is a certain standard that, if realized, would mean that the steering wheel can be fully and symmetrically operated without irrelevant back motions. Just arm movements. Back movements involve irrelevant muscles and will make you rattle about in the seat, making you lean against the steering. Likewise, the arms will maintain a bent position, in which the arm muscles be used for steering instead of the shoulders. Smaller muscle groups are more sensitive than larger ones, and this is also why we turn the wheel from the outside, not the inside. And I hope I don't need to tell anyone what happens to bolt-straight arms in a collision.

The reasons for the other parameters are also quite simple. The wrists gripping the wheel should be in line with the forearm, so that the carpal tunnel, hosting the median nerve (wow, when I write it, it doesn't sound so simple), causing a certain numbness in the palm. The palms needs to be lower than the shoulders so that the arms are not so outstretched forward and the shoulders remain at a more natural stance, allowing for the grip of the wheel to be less tiring. However, this creates a trade off with the ability to steer quickly, as the arms are partially obstructed by the body.

The body proportions are important because some of us have a long neck, which might cause a problem with steering height, or short arms that cause a problem with steering distance. If neck is too long, adjusting the wheel diameter and height as I described above, might not be optimal in terms of your clear view of the dashboard. If the arms are too short (relative to the legs) you will have to bring the steering itself closer to you. If it's the opposite, you will have to move the pedals forward.

I don't think there is quite a fixed formula. It changes not only depending on the driver's body, but also on the needs (a tighter track might require a smaller wheel) and even on personal preferences. Hence the subject of getting it all carefully adjusted and spending some practice sessions on making sure it all fits you.