UmneyDurak

Actually it does. The idea is to decrease lean angle not to increase through the turn. Thus it's a good idea to lower cg and put it on inside of the turn. Having pressure on outside peg will allow to put more downward pressure thus increasing contact patch (slightly), and be able to control rear wheel slide. There are two forces at play here. The downward force that keeps your wheel from sliding, and lateral force that tries to push your wheel sideways. When lateral force becomes greater then downward force wheel lets go. Having pressure on outside peg allows for quickly transfer even more weight and straighten the bike. Assuming if there is enough time to react.

Then of course we have flat tracking with dirt bikes. That adds a whole other level of complexity since now the rear wheel is under power through the turn. Although geometry of those bikes is different which I think also contributes to riding style vs road bikes.


What are we talking about again?

mattm

not sure. I wonder how much of the motorcycle theory translates to skinnier bicycle tires?

UmneyDurak

Great question. Maybe RacerEx would know, he knows about it way more then me. I would think at least some of sport bike theories apply to bicycles since geometry is similar. From personal perspective my BP is similar on bicycle descending to when I am on my sport bike. Except the whole knee thing, but there is no point to it on a street on motorcycles anyway (at least if one wants to live long enough). Different discussion thought.

Actually now that I think about there was this USA cycling email last year or so where some dude was giving points on descending on a bicycle. One of the points was to stick your knee out, because that's what motorcyclists do and it helps to stabilize a bike. I think that is what he said. Except the reason knee being used in motorcycles is to judge lean angle as a feeler. Stabilization comes from the gyroscopic affects.

Doge

Where the person's body is certainly matters in cornering, just not in grip.
But as you are asking what we are talking about - maybe you are not talking about grip.

The only thing that matters for grip is the gravitational force, the centripetal force (mass*velocity^2/radius of arc) and coefficient of friction between your tire and the road.
OR
"Tire grip", speed and radius your turn at that point.

If leaning increases grip because the tread is better, then it matters. If not - it doesn't.

Doge

Part II
That goofball picture above was during training by a many year motorcycle (road) racer. The same grip principles apply.

https://www.ultracyclingcoaching.com/...es/Page562.htm

UmneyDurak

It does matter where the body is. Since it affects CG of a system of rider and a bike. If it's on top of the bike pushing down it increases vertical force on a tire, at expense of increasing lean angle. If it's on an inside of a turn and lower you CG is lower and you can take the same corner at same speed with less lean angle, or at greater speed with more lean angle.

Now for your link. He doesn't really say anything that contradicts what I typed so far.

I believe I already said weight should be on outside, and that it helps to control loss of traction.
Your body can be on inside and still have the weight on that outside peg driving it down.

This particular bit deals with counter steering. A lot of people think that they steer the bike by shifting body weight. In reality what initiates that initial turn is handlebar input. Although I would add that you are pushing the bar "forward" not down i.e. ideally force you are applying to handle bar is horizontal to the ground. Now since bicycles are so light and speeds are not that great downward is good enough also.

Also since link you posted mentioned MotoGP...

Doge

Sounds like we are talking about different things. You sound as if you are discussing cornering. I'm discussing grip - sideway g force only.
You cannot increase average downward force by how you lean or twist. The average downward force on a flat road is only mass*gravity and nothing you can do in contorting your body will change that.

UmneyDurak

The location of the mass matters. It affects how much mass there is over the contact patch, and it affects how much the bike leans over (effective lean angle) given same corner and speed. Thus difference between seating in your seat and weighting outside the peg. With the increased lean angle there is an increase lateral forces. Which puts more stress on the amount of grip you have.

That being said.... Might not be all that applicable to bicycles afterall! Since tires are so thin.

gsteinb

TheKillerPenguin

That wall is awesome.

shovelhd

Is that Syracuse?

Grumpy McTrumpy

Saranac

revchuck 

I prefer Sazerac.

gsteinb

interestingly enough the town of saranac is about 40 miles from the town of saranac lake (where that race was) which is a mistake I made once when I wasn't particularly mindful programing the GPS.

carpediemracing 

Question I thought of when thinking of stuff I need to do for this coming season, aka "gluing tires".

I'm thinking of gluing up a set of rain wheels. I basically have a set of full on race wheels (Stinger 7/9) and the rear has a rain tire on it (Vittoria Evo Tech). I really don't do much in the rain, I haven't really kept up on stuff, so I had a question about what people prefer for set up in the rain. I was thinking of wider, softer tires, realistically on the Stinger 4 front that I bought but never rode.

For regular stuff I use 23mm 120 psi tubulars. I was thinking of either 23mm rain specific tires (I have a couple more Vittoria Evo Tech) or maybe later getting some 25mm tires, if they clear my frame/etc.

Other thoughts/ideas? Other than ride/race/corner in the rain more?

shovelhd

If I had multiple sets of race wheels I would have a rain set for sure. Last year I raced on GP4000s clinchers in the rain, mainly because I had ridden them extensively in the wet and trusted them. This year I will use the tubular race wheels with Corsa CX but in 25mm.

Do you think a 25mm tire will fit in your rear triangle? It's crazy tight last time I looked.

mattm

rad.

in WA there is a crit corner with a walled exit like that, but wider and minus the pads. I once came out too wide and had to lean against the wall, scraping my knuckles/shoulder on it and somehow not crashing..

I still wear the gloves with holes in them, @Ygduf knows!

grolby

There was a crit in Tennessee one year (Johnson City, maybe?) that apparently took the course down an alley to get between two main streets. Complete with a dumpster against a building wall. Yeah. Apparently it was terrifying. There's something about Tennessee and scary crits... the Highland Rim Omnium one year had a criterium on a .4 mile course in downtown McMinnville. Yes, .4 miles. Skinny rectangle, with the long bits both downhill and all the elevation on the short bits. Scariest crit I've ever done, and that includes one I did in Knoxville that was basically on the side of a mountain.

gsteinb

yeah that was a fun crit course. Directly after that turn the road turned up, and the race would detonate. That tight turn, followed by the incline made it very hard to follow wheels unless your were upfront. Unfortunately that race is no more, but it was replaced with a really awesome circuit race a few miles from my house.

hack

I think the tightest one around here is a little alley down at the Original Merced Crit. It makes a few cameo shots in this vid (as does Matt):

furiousferret

The best advice I got for cornering was from Phil Gaimon's book. Accelerate into the corners. For me I have more control when variables change while in the corner (guy in front braking, debris, etc.) and at least at my level of racing can pass 10 guys if there is an open line.

TheKillerPenguin

I learned how to corner via Gran Turismo...go as fast as possible and try to bump off everyone else.

furiousferret

This is more like how I corner:



I just wanted to find a way to post this gif.

grolby

I tried that in a 'cross race, once. Ended up eating a lot of grass.

There's so much advice in so many books out there. And I think its real-life usefulness is limited in a lot of ways. The biggest ones are that some people who are good at doing something have no idea why they are good at it, so their advice is uninformative, and that all the theory in the world is no substitute for experience and practice in the real world. And of course "the real world" often means buried in the peloton at high speeds elbow-to-elbow with 30-50+ other dudes and learning that you can only do the same thing that everyone else is doing. Being able to pick a smart line is good, and can be used to your advantage in a few situations, but a lot of the time the riders I see who have trouble with cornering don't have a problem with lines, they lack confidence in what the peloton is doing* and they lack confidence in their equipment to stay stuck to the pavement at the speed the pack is moving at.

*Sometimes justifiably, natch, but usually to the detriment of their safety and everyone else's.

gsteinb

isn't that the point of cross? sounds like it worked.