# What is the maximum lean angle on a standard road bike tire? Photo NWS!



## Williams700 (Jul 18, 2005)

I really thought I had left the world of road rash after I stopped motorcycling. Apparently I was wrong. I went into a tight hairpin this morning going about 24mph. I'm pretty used to taking these turns on my motorcycle with no problem - kneedragging and all. So I go into the turn, I look through the turn and the next thing I know is that I lose my edge on the wheel and I skid on my hip for a good 8 feet. The SUV behind me swerves out of the way to avoid hitting me. Now I have this lovely scar to add to my collection - this is the 2nd fall I've taken in the last 3 days! Who said cycling was safer than motorcycling!?!

So my question again is - how far can you lean on a standard road bike tire in a turn? I've figured out now the tire isn't like a motorcycle's tire width.


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## Marc (Jan 23, 2005)

Williams700 said:


> So my question again is - how far can you lean on a standard road bike tire in a turn? I've figured out now the tire isn't like a motorcycle's tire width.


 Ouch....I've done thhat a couple of times (spaced out-having waay too much fun)....are we presuming a zero bank of the road?

Racing slicks?
your mass?
speed of turn....

lots of vars, makes it a fun physics problem


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## wim (Feb 28, 2005)

*Jobst Brandt on Descending.*

_Cut and pasted from a long Jobst Brandt newsgroup post. Earlier in his post, Jobst explains how motorcycles can apply power in hard turn and initiate a rear-wheel slide, thus recovering. Bicycles can't apply power in hard, fast turns to initiate slides or drifts, so they go down once the traction limit is exceeded._

Quote: "Cornering requires assessing the required lean angle before reaching 
the apex of the turn. The angle with the road surface is the critical 
parameter. This angle is limited by the available traction that the 
must assess from velocity and apparent traction. For good pavement, 
this angle is about 45 degrees, in the absence of oil, water, or smooth 
and slick spots. Therefore, a curve banked inward 10 degrees, allows 
a lean of up to 55 degrees from the vertical, while a crowned road 
with no banking, where the surface falls off about 10 degrees, would 
allow only up to 35 degrees."


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## rriddle3 (Aug 5, 2004)

Williams700 said:


> ...I'm pretty used to taking these turns on my motorcycle with no problem - kneedragging and all...


Hope you don't stick your inside knee outward like on a motorcycle turn. That only shifts your center of gravity away from the frame of the bicycle.


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## il sogno (Jul 15, 2002)

I remember reading in a motorcycle magazine that the wider the diameter of the tire, the more you are supposed to lean while cornering. Considering that a road bike tire is kind of skinny, I'd concentrate on staying a bit more upright than you're used to. As it is with motorcycles (and with skiing), cornering quickly on a bicycle requires techniques that initially seem kind of illogical. For example, if you want to corner quickly on the bicycle, put your inside foot up, your outside foot down, and put as much weight as possible on that outside foot as you go through the turn. It's almost magical how effectively this little trick works. As for Middle3's advice not to stick your inside knee outwards, I've found that it works just fine...though you only need to do it during the tightest, gnarliest turns.


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## Kerry Irons (Feb 25, 2002)

*Huh?*



rriddle3 said:


> Hope you don't stick your inside knee outward like on a motorcycle turn. That only shifts your center of gravity away from the frame of the bicycle.


Gee, when I watch bike racing footage, I see all kinds of pros doing this very thing, just as they have been doing for many years. What is it that you know that these pros apparently misunderstand?


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## TurboTurtle (Feb 4, 2004)

Kerry Irons said:


> Gee, when I watch bike racing footage, I see all kinds of pros doing this very thing, just as they have been doing for many years. What is it that you know that these pros apparently misunderstand?


Some pros do, some don't. I believe the current "best available information" says tight to the top tube is best. Just goes to show that what the pros do isn't always correct or they wouldn't be constantly changing. - TF

BTW, I have to include my favorite cornering picture. Apologies to those who are viewing it again. (Note knee is in.)


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## rriddle3 (Aug 5, 2004)

Kerry Irons said:


> Gee, when I watch bike racing footage, I see all kinds of pros doing this very thing, just as they have been doing for many years. What is it that you know that these pros apparently misunderstand?


My, Kerry, did you get out of bed on the snotty side again? I don't claim to know anything except a rudimentary knowledge of physics and bike handling, but here is a quote from Sheldon Brown's website, so at least I'm not unique in my ignorance.  

You can verify this yourself by performing an experiment suggested by Jobst Brandt: 
"Some riders believe that *sticking out their knee* or leaning their body away from the bike, improves cornering. Sticking out a knee is the same thing that riders without cleats do when they stick out a foot in dirt track motorcycle fashion. It is a useless but reassuring gesture that, on uneven roads, actually works against you. Any body weight that is not centered over the bicycle (leaning the bike or *sticking out a knee*) puts a side load on the bicycle, and side loads cause steering motions if the road is not smooth. Getting weight off the saddle is also made more difficult by such maneuvers.
"To verify this, ride down a straight but rough road standing on one pedal with the bike slanted, and note how the bike follows an erratic line. In contrast, if you ride centered on the bike you can ride no-hands perfectly straight over rough road. When you lean off the bike you cannot ride a smooth line over road irregularities, especially in curves. For best control, stay centered over your bike."


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## il sogno (Jul 15, 2002)

I do "tight to top tube" and "knee-down" both. I agree that "tight-to-top-tube" works better when it comes to rough roads, tricky lines, etc.; but for sheer cornering velocity or for decreasing radius downhill turns, knee-down keeps me from sailing off the cliff. It might be mentioned, too, that the pro considered to be the best descender in the game, Paolo Savoldelli, is a knee-down guy.

In any case, as can be seen there are differing schools of thought here. As it is with everything else in life, there's more than one way to skin a cat (or to avoid skinning a thigh). Best of luck.


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## Argentius (Aug 26, 2004)

*Why not knee down?*

Clearly it can't help you 'feel out the turn' like you do when you slide it on a motorcycle; I'm a newb to high cornering speeds on bicycles but it just feels like a reassuring gesture to me.

When I watch pros, it seems like (as mentioned above) some stick out the knee, some don't; at a glance I can't seem to see that either group has the 'better' descenders.

With a motorcycle, you shift your weight towards the inside of the corner by sliding your hips off the saddle so that you can get more force leaning you into the corner, and so that the bike will need to be at a relatively lower lean angle to accomplish the same speed / radius of turn.

On a bicycle, I know it's going to be a different game, since the rider weighs 10 times what the machine does, rather than half or less, plus there's on-throttle rear grip to be concerned about.

Overall, is there a physics reason why you'd lean the bicycle more, less, or the same amount as the rider?


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## HAL9000 (May 1, 2002)

Nice tighty-whities!


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## TurboTurtle (Feb 4, 2004)

"When I watch pros, it seems like (as mentioned above) some stick out the knee, some don't; at a glance I can't seem to see that either group has the 'better' descenders."

I think the knee down style helps because it causes your body to turn in the direction of the turn. Squaring your upper body to the radius of the turn is a technique used by Ned Overend. - TF


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## Kerry Irons (Feb 25, 2002)

*Absolutism*



rriddle3 said:


> My, Kerry, did you get out of bed on the snotty side again? I don't claim to know anything except a rudimentary knowledge of physics and bike handling, but here is a quote from Sheldon Brown's website, so at least I'm not unique in my ignorance.


Well, you stated, rather unequivocally: "Hope you don't stick your inside knee outward like on a motorcycle turn. That only shifts your center of gravity away from the frame of the bicycle." That sure implied to me that there was no way this person (or any other) should be sticking their knee out for turns. And yet, as others have noted here and I was trying to point out, many pros do just that. It's one thing to state that there are two sides to the discussion, or that there are times when you shouldn't stick your knee out, but you didn't do that. You just said it was wrong. Did I miss something?


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## RiDE (May 28, 2004)

I don't know but I'll be watching these guys to find out.


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## weltyed (Feb 6, 2004)

too bad he bit it on this turn and lost the race...maybe you shouldnt corver like this.


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## TurboTurtle (Feb 4, 2004)

weltyed said:


> too bad he bit it on this turn and lost the race...maybe you shouldnt corver like this.


Yea, but it was close. If it hadn't been for that row of bricks... TF


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## Cory (Jan 29, 2004)

*Don't forget that motorcycle guys drag a foot.*

I just skimmed the posts on this, but FWIW, dirt trackers actually drag a foot in the turns, not just put out a knee. I'm way too slow and chicken to be any good at it, but I've been passed by hundreds of guys who can do it.. 
As for the effect of an extended knee on the center of gravity or the cornering speed of a bicycle . . . any time I start having those thoughts, I slow down.


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## everydaybike (Feb 25, 2005)

Cory said:


> I just skimmed the posts on this, but FWIW, dirt trackers actually drag a foot in the turns, not just put out a knee. I'm way too slow and chicken to be any good at it, but I've been passed by hundreds of guys who can do it..
> As for the effect of an extended knee on the center of gravity or the cornering speed of a bicycle . . . any time I start having those thoughts, I slow down.



Just a friendly FYI... 

In a past life I did the hard core motorcycle racing thing. Started out on short tack and ended up calling it quits at Daytona during the 200 mile classic when a guy named Kenny Roberts blew by me (and many others) doing a 100mph wheelie on his new Team Yamaha TZ750... Early 1970's Now, I'm strickly on a bicycle although I often think of getting a new crotchrocket but I realize the body doesn't heal as fast as when I was in my twenties.

Dirt trackers, (in the old days it was flat trackers) used a gizmo called a hot shoe which consisted of a steel plate that was attached to your left riding boot. At high speeds like on a mile track, the toe usually got dragged slightly to help control the slide. On the shorter tracks, 1/4 mile, the foot got planted hard into the dirt to control the slide and the back end of the bike. It's done in conjunction with a heavy twist on the throttle at full power. It was, however, a manuver that maintained control after the rear tire and sometimes the front lost traction and you were in a slide intentionally.

It's very diffferent on a bicycle. You need to keep the speed and lean angle in check based on ability and road surface. It's a balance of weight and enertia. You have to keep your center of gravity low and to the outside so you don't lose traction. Keeping the outside leg stiff while pushing down on the pedal and the inside knee clamped tight against the TT is the best way to accomplish this. Some do the leg hang out thing which is my opinion places the center of gravity high and to the inside. I've done both mainly because of what I learned racing motorcycles and for me the better, faster, more stable way to approach a high speed turn in leg down, knee in. The first rule I follow is to not push the speed any faster than what I feel the road or the tire can handle and keep my center of gravity as low and outside as I can. Losing traction on a bicycle sucks. 

That's of course is only MHO...

Cheers


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## XC Roadee (Apr 1, 2005)

*Heres a helpful link on cornering*

http://www.racelistings.com/rzone/articles/article.asp?recid=320

I haven't read all the posts but I believe the knee out technique is used in the Countersteering method of cornering but would be a bad idea if you're Leaning through a corner, which means almost everyone of you is correct in you assertions. 

As someone said earlier you'll need to decide what cornering method you be using way before you hit the turn. For smooth high speed turns where I have a good view of the entire corner I prefer the Leaning technique, for more dicey/technical corners I prefer to Countersteer knee out and all since I feel like this gives me way more control of the bike, you're supposed to shift all your weight on the outside pedal anyway so I'm not worried about my inside knees altering my center of gravity. 

I almost always strictly use countersteering when riding the MTB


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## XC Roadee (Apr 1, 2005)

*oh and to directly answer the original question*

the maximum lean angle is the degree of lean you hit right before you go careening out of control and skidding 8ft before coming to a stop  . I'd think you'd know this by now


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