Calculating minimum turning radius

You might consider contacting your state MSF office to see if they offer a UBBC (Ultimate Bike Bonding Course) anywhere in the state or nearby states. This is a course that concentrates on slow speed handling skills. It can be taken on any street bike, and is basically an introductory level motor officer skills course.

The absolute minimum turning radius is not as important as the minimum turning radius YOU can accomplish on YOUR bike in a repeatable manner, without having to resort to the HD shuffle.

Better riding thru training, not math.

Friedle
MSF 27713

Friedle said:

You might consider contacting your state MSF office to see if they offer a UBBC (Ultimate Bike Bonding Course) anywhere in the state or nearby states. This is a course that concentrates on slow speed handling skills. It can be taken on any street bike, and is basically an introductory level motor officer skills course.

The absolute minimum turning radius is not as important as the minimum turning radius YOU can accomplish on YOUR bike in a repeatable manner, without having to resort to the HD shuffle.

Better riding thru training, not math.

Friedle
MSF 27713

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I've got two police courses behind me, the training is there. The absolute minimum turning radius is a reference point for where you are in relation to what the bike is capable of physically. No more or less.

Wheelbase will affect numbers, thus the question asked about how to determine turning radius potential, based on wheelbase. Each bike model/make will be different.

brownie0486 said:

Like this guy. Upright, it appears his GS turns in something around 15 feet [ two car slots are 18 feet ]. When he leans the bike, looks like he's scrubbing another 2+ feet off that diameter for something around 12-13 feet in diameter.

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Thanks for the youtube video...it is simple, straight forward, good info.

brownie0486 said:

I've got two police courses behind me, the training is there. The absolute minimum turning radius is a reference point for where you are in relation to what the bike is capable of physically. No more or less.

Wheelbase will affect numbers, thus the question asked about how to determine turning radius potential, based on wheelbase. Each bike model/make will be different.

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If you already have the training, then just go ride and figure it out. The machine will have a large part in the determination. I can turn tighter circles on a Grom than a chopper. I still maintain that the important point is how tight can you comfortably circle your bike as opposed to that the calculator might determine.

Friedle

Friedle said:

If you already have the training, then just go ride and figure it out. The machine will have a large part in the determination. I can turn tighter circles on a Grom than a chopper. I still maintain that the important point is how tight can you comfortably circle your bike as opposed to that the calculator might determine.

Friedle

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My skills compared to what the bike is capable of producing mechanically gives insight where one sits on slow speed turns. I prefer to have a base to work from, what's the minimum turning radius any particular bike is capable of and comparing that to present skills levels.

Bolded, and that's exactly what I'm trying to determine with this thread.

I can turn tighter circles on a Grom than a chopper

But do you know their minimum turning radius' based on wheelbase so you could compare mechanical limitations vs your current riding skills?

Unless I totally missed the point of the video, I stand by my earlier post #3. The minimum radius is achieved when the rider is capable of leaning and balancing the bike - way leaned over and still not lying on the ground. It isn't the full lock radius with the bike upright. I suppose it is possible for a couple of folks to roll a bike around with a lean of some prescribed angle, but what that angle needs to be which can still be achieved by a mounted rider at an achievable slow speed is hard to guess.

PGlaves said:

Unless I totally missed the point of the video, I stand by my earlier post #3. The minimum radius is achieved when the rider is capable of leaning and balancing the bike - way leaned over and still not lying on the ground. It isn't the full lock radius with the bike upright. I suppose it is possible for a couple of folks to roll a bike around with a lean of some prescribed angle, but what that angle needs to be which can still be achieved by a mounted rider at an achievable slow speed is hard to guess.

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Interesting video on lean angles

flhfxd said:

Is this a legit question? Why in the name of all things holy would you even care...?

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rhodetrip said:

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What I'm getting here from some is that because I asked a question no one seems to be able to answer, it must be a dumb question. Does it freakin matter the motive for asking the question?

brownie0486 said:

What I'm getting here from some is that because I asked a question no one seems to be able to answer, it must be a dumb question. Does it freakin matter the motive for asking the question?

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It doesn't really matter. But, since the answer is quite subjective, knowing why the information was wanted might help somebody formulate a useful answer. Just guessing.

PGlaves said:

It doesn't really matter. But, since the answer is quite subjective, knowing why the information was wanted might help somebody formulate a useful answer. Just guessing.

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Post 10 seem to answer the why? Or perhaps not.

brownie0486 said:

What I'm getting here from some is that because I asked a question no one seems to be able to answer, it must be a dumb question. Does it freakin matter the motive for asking the question?

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How high is up?

Not a dumb question, but finding an exact answer has to assume values for too many variables to be useful, so nobody bothers.

How far can the rider lean and maintain control with the fork on the steering stops? Speed changes height and effective wheelbase, as does the load. An actual calculation will probably also need to consider fork length, trail, rake, tire diameters and widths, and much more. Easier to find a puddle in a parking lot, wet your tires, lay the bike on it's side, power through a circle, and measure the resulting track.

It's safe to say the GS turning circle is less than 16 feet, more than 12 feet, the rest depends on the rider.

I can turn my RT in 16 ft in a parking lot, and could probably reduce that with practice. I don't do u-turns in my 16 ft driveway because If I run off the edge, I'll likely drop the bike.

My brother-in-law has to back up to turn in 18 ft.

The only useful number is how small a circle YOU can ride.

As I have said before, the math doesn't matter. Skill and technique matter.

Turn the handlebars to full lock, counterweight the hell out of the bike and skillfully coordinate throttle, clutch and rear brake while dragging the hard parts of the bike all the way around a 360 degree turn. That will be the minimum practical, as opposed to calculated or theoretical, turning radius for Your bike and Your skill level.

Does it really matter if on paper you should be able to turn in a 16 foot radius, but the best you can manage in the real world is 23 feet?? YOUR minimum turning radius is 23 feet. Welcome to the real world.

Friedle

Friedle said:

As I have said before, the math doesn't matter. Skill and technique matter.

Turn the handlebars to full lock, counterweight the hell out of the bike and skillfully coordinate throttle, clutch and rear brake while dragging the hard parts of the bike all the way around a 360 degree turn. That will be the minimum practical, as opposed to calculated or theoretical, turning radius for Your bike and Your skill level.

Does it really matter if on paper you should be able to turn in a 16 foot radius, but the best you can manage in the real world is 23 feet?? YOUR minimum turning radius is 23 feet. Welcome to the real world.

Friedle

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Why yes it does, IF one wants to work on their skills and have full command of the bike in slow speed turns. Someone doing 23 foot circles on any bike, that can do physically do 16 footers, doesn't have full command of that bike. If one can do 23's and the bike is physically capable of 16's, then one has something to work toward to improve their skills on that bike IF they want to improve their control/command of that particular bike.

As an example, there's cone course riders that use the LT, they have a problem with 16's based on wheelbase, yet a few can do the 16 foot challenges, that gives insight and a goal to work toward if they own an LT. It may not matter to the majority, it may seem irrelevant to the majority, but to the LT cone event riders understand the bike CAN do 16's, so that's a goal to work toward in the pursuit of full command of their bike.

When training with Hawthorne PD in Ca., I didn't think my GT would do 16's, till a motor officer jumped on my bike and did 16's like it was 20's. I wondered just how tight a circle it could really turn, and his demonstration gave me goals to improve my own skills, knowing the bike was capable of 16's and likely somewhat less than that. The progression of that thought process led to the threads question.

It may be something that can't be ascertained, and if that's the case, then the question has still been answered. I appreciate everyone's input, next weekend I'll pose the question to high level competitors at a major day long cone event.

brownie0486 said:

If we can establish an upright turning radius, then it will be less when leaning the bike in cone events. Just looking for the turning radius of the bike if you walked it in a circle bars at full lock.

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of course if that is all that is being sought, then no math is needed. find some pavement and walk the bike in a circle with bars at full lock. done.

On my '05 Ultra Classic I used to do full lock, leaned over turns in my back yard in the grass. For some reason I could not get comfortable doing the same on my later Harleys. Not sure if it was the frame change in '09, or the high speed crash I had in '10 that frazzled my nerves.

My '05 was very comfortable doing low speed, full lock turns. I used to do figure 8s in most any parking lot, with my wife on back while we were waiting for other riders to gear up.

I hit the ditch back in '10 doing 70 MPH, long story, my fault, (one of the few accidents I know of where it was the rider's fault!) but that wreck took me a couple years of riding to feel somewhat normal, and I have not gotten back to that comfort level I had before the wreck yet. Also I am 60 years old and I am feeling the results of time nagging at me a bit too.

PoorUB said:

On my '05 Ultra Classic I used to do full lock, leaned over turns in my back yard in the grass. For some reason I could not get comfortable doing the same on my later Harleys. Not sure if it was the frame change in '09, or the high speed crash I had in '10 that frazzled my nerves.

My '05 was very comfortable doing low speed, full lock turns. I used to do figure 8s in most any parking lot, with my wife on back while we were waiting for other riders to gear up.

I hit the ditch back in '10 doing 70 MPH, long story, my fault, (one of the few accidents I know of where it was the rider's fault!) but that wreck took me a couple years of riding to feel somewhat normal, and I have not gotten back to that comfort level I had before the wreck yet. Also I am 60 years old and I am feeling the results of time nagging at me a bit too.

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99-06 road kings seem to be the preferred bike for many. I'm told 07 on they stretched the frame an inch or so, not as adept in the tighter cone patterns. One of the reasons for the thread. The BMW LT's have a harder time doing 18's due to wheelbase length.

brownie0486 said:

What I'm getting here from some is that because I asked a question no one seems to be able to answer, it must be a dumb question. Does it freakin matter the motive for asking the question?

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Do you have a lean angle indicator on your bike that you reference?

rhodetrip said:

Do you have a lean angle indicator on your bike that you reference?

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Sure do, me. It's coupled to the motion indicators that extrapolate slow speed through the seat pan. Between the two, proper lean angle can be applied. The formula tends to be flexible based on tire selection/composition and tire pressures.

PGlaves said:

The minimum turning radius at full lock and the radius which can be achieved by a trained (moto Cop style) competitive cone rider are not the same and would be hard to calculate in any event.

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I dropped my RT on its side twice practicing this when I first got the bike. I have yet to scrape the ground with body work at full lock. Full lock just got less full with the addition of the mounts for the BMW tank bag which I need to modify.