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Old 09-17-2013, 01:03 PM   #1
Cakeeater OP
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Harley ABS Braking: Front,back, both.

Harley now has linked brakes on their newest bikes. Other brands offer this, I know...but I was curious to measure stopping distances with just back, just front, and both brakes.

So I headed to my favorite empty parking lot with some chalk and a tape measure.

Bike: 2011 Harley Road Glide Ultra (that's the one with fixed fairing and all the bags and do-dads on it). New front tire, newish back tire. ABS brakes.

Pavement is parking lot by the local pool, and cops are always driving by, so I tested 30 mph to 0 stoping distances. Asphalt is weathered and pretty clean.

It's a windy day, and I did the test with a tailwind. Maybe 10-15 mph? Enough so that my metal tape measure was blowing around, and enough that it might have added a foot or two to stopping distances.

The tail wind made it easy to always nail 30 mph. Get up to speed...pull in clutch...coast across the line and hit the brakes. ABS makes the test stupid simple.

Both brakes:
From 26.5 feet to 31 feet. Tested five different times. I was surprised at the variance...sometimes the brakes didn't hit as hard as I liked right off the bat.

Front brake alone:
41 feet.

Rear brake alone:
69 feet!!

Message to riders who only use their back brake (pass this along to newbies and many many Harley riders): Dragging your feet might be more effective than just using your back brake. Jeesh, took a long time to stop.

Just for fun, I braked into the wind twice: 28 feet and one under 25, but maybe I was feathering the brake a bit before that last one.

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Old 09-17-2013, 02:20 PM   #2
anotherguy
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Why would you feather ABS brakes?
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Old 09-17-2013, 02:30 PM   #3
JerryH
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Why would you need to be concerned with controlling ABS brakes at all? Isn't that what the computer is for? Just apply the brakes really hard every time, and let the computer bring the bike to a nice controlled stop.
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Old 09-17-2013, 04:29 PM   #4
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Quote:
Originally Posted by anotherguy View Post
Why would you feather ABS brakes?
Wrong word: "riding" the brakes. Meaning, i probably jumped on 'em too soon.

Jerry: Yes, all one does with ABS is squeeze and push...just like with me lady.

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Old 09-17-2013, 04:32 PM   #5
dduelin
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Jerry,

The presence of ABS does not repeal the physics of weight transfer. In order to stop in the least distance the rider still needs to squeeeeeeeze one-two before maximum braking in order to let the front tire develop the highest possible friction coefficient from weight transfer mashing the tire into the pavement. If one just grabs as much front brake as possible with no skill the front tire locks up before developing maximum braking force then ABS releases brake pressure before coming back to maximum braking. That moment of brake, ABS release, brake adds to the stopping distance.

This question perfectly illustrates why ABS does not remove the need to learn and practice threshold braking skills.
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Old 09-17-2013, 05:44 PM   #6
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Quote:
Originally Posted by dduelin View Post
Jerry,

The presence of ABS does not repeal the physics of weight transfer. In order to stop in the least distance the rider still needs to squeeeeeeeze one-two before maximum braking in order to let the front tire develop the highest possible friction coefficient from weight transfer mashing the tire into the pavement. If one just grabs as much front brake as possible with no skill the front tire locks up before developing maximum braking force then ABS releases brake pressure before coming back to maximum braking. That moment of brake, ABS release, brake adds to the stopping distance.

This question perfectly illustrates why ABS does not remove the need to learn and practice threshold braking skills.
I know you're directing this at Jerry...however...:

I'd agree with you but I didn't "test" that. Today all I wanted to do was measure rear-brake only distances compared to front brake, and both, and letting ABS do all the thinking. I think that's why my distances varied, because by just "hammering" on the brakes right away the ABS would immediately kick in and skip a bit. My shortest distances were probably when I was easier on the brakes. But, that's what I did.

For me, I grew up riding/racing road bicycles. I eventually removed the rear brake calipers. I thought it looked cool, and it saved a whole 1.2 ounces, and I loved stopping with my back wheel high in the air. When I transfered over to street bikes I practiced pretty much the same technique. Depending on the bike I'd either practice impending front wheel lockup or stoppies. I got in the habit of not using my back brake much. Bad habit, probably.

Now that I have ABS I can brake like a caveman if I want. Is it as "short" in perfect conditions? I dunno. In the real world I still brake like I don't have ABS. I've never crashed (knock on wood) from braking hard. I low-sided once in a corner on pavement and last winter I wheelied a hopped up mini-moto on its back in a corner and broke my ribs, which sucked, but I like to think I can brake okay.

I'm sure there are plenty of other tests out there showing the difference between front/back/both, but I can't remember seeing any. it was fun to do.

And btw, I'd never buy another streetbike without ABS. It's just so awesome in the rain.


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