Rubber Meets The Road

If you don’t think that your physics classes were very interesting, hop on a motorcycle and whip through a corner or two. You’ll probably start thinking about those few square inches of rubber that are touching the pavement and somehow holding you in place. How does that really work?

Most of this post is a summary of a longer article so please head there if you want the full story. There are a lot of other good motorcycle physics discussions there too. The basic idea is that there are two laws of friction:

  1. Friction increases as weight increases.
  2. Friction is independent of the contact area.

The first one makes sense, but the second one probably sounds a bit odd. It states that if you set a brick on it’s end or on it’s side, it will start sliding at exactly the same angle either way. It might sound crazy, but it’s true.

So let’s apply this to a motorcycle. The first law states that when you brake you have more traction on the front tire because the weight is transferred to that tire. The second law says that when you corner, you have the same amount traction than you did standing up straight because you have the same weight of the bike pushing down into the pavement. (The force imparted from going around a corner is parallel to the ground so that doesn’t give you additional friction.) However, while you may have the same amount of total traction in a corner, you’re also using up more of your available traction to go around the corner. You can’t grab a handful of brake and expect good things to happen.

The second law always means that the size of the tire makes no difference in the amount of traction you have. In theory, if you built a bicycle tire and a motorcycle tire out of the same rubber compound, they would provide you with the exact same amount of traction. So why are motorcycle tires fatter? You get better handling characteristics from having a tire with a bigger curve on it. You don’t go from tread to sidewall as quickly when you lean over as you would with a bike. Also, most motorcycle tires have a tougher rubber compound in the middle for long tire life and a software compound on the sides for more grip.

Physics isn’t just a good idea, it’s the law!

Cruiser vs. Crotch Rocket

There have been a lot of conversations directed at me lately implying that my choice of motorcycle was ridiculous. This comes mostly from pure sport bike riders claiming that my bike is “slow.” However, a couple of the questions have been honest questions from new riders so I’ll give a little spiel about why I love my bike in hopes that it will help some of you decide what you want to buy.

There are two basic styles of motorcycles for the road: cruisers and sport bikes. On a cruiser you sit straight up with your legs out in front. Think of a Harley. On a sport bike the handlebars are very low requiring you to lean forward and tuck your legs up under you. This is what you see people racing on TV.

Cruisers are great for long rides. They’re very comfortable and while you’ll get sore, you could put in a 500 mile day and still be able to move the next day. Sport bikes are built for speed and they can be quite a bit faster than cruisers. Generally, the faster your sport bike is, the shorter the distance you can ride before you turn into a giant cramp. You might think twice about 100 miles on a sport bike, but you’ll experience more thrills in those 100 miles than you would on a cruiser.

Now of course I’m generalizing and it all depends on the specific bike. MattM has a bike that would fall in the sport bike category but he puts in way more miles than I ever have on any of my bikes. But in general, I think the above paragraph holds up.

My bike, a 2009 Kawasaki Concours 14 ABS, falls into a tiny category called “sport touring.” Actually Kawasaki calls it “super sport touring” to reflect it’s race bred ancestors. It’s more of a niche market but it attempts to combine the performance of a sport bike with the comfort of a cruiser. Of course you can’t get the best of both worlds, but this bike comes pretty close. It has gobs more speed than you can ever pretend to use on a street (0-100mph in 4.7seconds?!?), but the seating position is much more upright giving you the ability to ride a lot farther each day.

It’s probably not a great category for your first bike since these bikes tend to be pretty heavy and they have huge engines that can get you in a lot of trouble. But if you like taking overnight trips but you want a little pep in your step, it’s a great style!

What’s next for me? Of course I dream about that a lot. I think I’ll have this for many years down the road, but when it does come time to sell it, I think I’d strongly consider going full “old man” bike. After I’ve hit 300-400 miles in a day, I really envy those guys on Goldwings with arm and backrests!

Your Mileage May Vary

If you’ve used a GPS in your car, you may have noticed that it doesn’t match your speedometer and odometer. Just about every car on the market has about a 3% difference between your actual speed and the displayed speed. (You’re really going slower than you think.) Imagine the lawsuits if people were getting pulled over because their speedometer reported that they were going slower than they really were. The difference can vary by car, tire size, etc.

Since getting the latest set of tires on my motorcycle, I noticed that my speedometer was getting pretty far off. It’s annoying to do math just to figure out how fast I’m really going. An actual speed of 60mph was reported as something more like 63-64mph. It also means that you’re racking up the miles faster which devalues your vehicle quicker than it should.

Enter the Speedohealer. They make a little box that connects in between your speed sensor and the dash. (Vist the HealTech web site to find the correct wiring harness for your bike.) You tell it exactly how much your gauges are off and it will make sure your gauges read correctly. I did a couple tests on the interstate with a GPS measuring my actual speed until I got it dialed in correctly. The unit also comes with a little button that you can mount somewhere near your dash that will recall your max speed and display it on the speedometer.

Installation on my 2009 Concours wasn’t just plug and play. When the unit was connected, the bike got a little hitch in it’s giddy up at low speeds. The instructions with the unit (specific for my bike) said that I needed to send the unaltered speed signal straight to the ECU. That meant cutting one wire from the main wiring harness and splicing in another one. I had to make the cut right by the plug going into the ECU, so if I did something wrong, it would have been very difficult to repair. I finally took the plunge and made the snip with visions of a four digit repair bill if I screwed it up. Thankfully all went well.

I hesitated to post this because I wasn’t sure how legal it was to monkey with your odometer, but I couldn’t find anything that said it was illegal to calibrate it correctly. Either way, I’m happy to be able to tell how fast I’m really going and have my odometer read the correct mileage. I don’t usually carry a mapping GPS on the bike so when I need to make a turn in 17.4 miles, I’ll actually be able to find it now!

Michelin Pilot Road 3

The front tire on my 2009 Kawasaki Concours has been wearing out and after 9700 miles, I no longer had much confidence in it. The back tire still looked pretty good, but I shopped around and decided to pull the trigger on new tires. The tech at Waldron Kawasaki suggested that I take the old rear tire home as a spare in case something happens to this new one and I don’t feel like shelling out the money for another tire right away. 10,000 miles isn’t a lot, but it’s not too low for a sport bike or a “super sport touring” bike which is what the classification of this bike.

The Bridgestones that came with the bike weren’t great and the compound on the front tires for the 09 model is notorious for being too soft and wearing out quickly. I opted for the Michelin PR3’s after quite a bit of internet research and talking to the guys at the shop.

First of all, it looks visually like it might be some kind of rain tire. The tire is siped and can move a lot of water on wet days, but it’s still very durable for hard riding and will last a long time. When people see the tire, the general reaction is that there is too much tread and there can’t be enough grip. However, a UK magazine did a wet weather test and was able to lean the bike over in the rain and drag a knee. Another reviewer took them to the famous Spa race track, ran a bunch of laps, and then ran thousands of miles with them on normal roads. Not too shabby!

The tire is dual compound which means the middle is a harder compound for long life and the sides are softer for increased grip in the corners. Reviewers also say that this tire is incredibly quick to warm up and you get good grip almost as soon as you leave the driveway.

Since this is the first time I’ve ever purchased new tires for a motorcycle, I don’t claim to be any kind of expert, but it’s cool to see how much technology and progress there is in the tire world. I was surprised that I could feel a difference when I rolled out of the dealer, but I don’t know if that was just because the tires were a different shape. The old ones were squared off a bit. Whether I’ll be able to tell a difference beyond that or not, I hope these last me for another 10K miles and beyond!

Beware Of Bikers

It’s been almost four years since I wrote a post called “What Motorcyclists Wish You Knew.” While I still wish that every driver would read that post, I realize that there are always going to be bad drivers out there and it’s up to me to stay safe. I’ve been riding for seven years now and I feel like I’ve developed a sixth sense about traffic situations. 99% of people on the road follow a bunch of undefined social norms. The trick is to look for any car that is straying even slightly from the norm. It’s easy to spot the guy flying up behind you and weaving in and out of traffic erratically, but what about that car about a quarter mile up who keeps drifting slightly out of their lane or the person in the lane next to you who keeps slowing down to 50 before speeding back up to the speed limit. Those people seem more dangerous to me because they’re probably on their phones and are very unaware of what’s going on around them.

But if I could boil down that previous post to one item and share it with everyone, it would be “don’t ever enter a lane in front of a motorcycle.” That means don’t merge in front of a motorcycle on a highway or pull out in front of a motorcycle from a side street. It’s really hard to judge the speed of a motorcycle with a quick glance since the size is so different. Now if you turn on your blinker, wait for the biker to acknowledge you and wave you over, by all means go for it. But squeezing into that little space like you would between two cars is just not smart.

And while we’re at it, this applies to trucks too. I spent a lot of time on 405 in stop and go traffic and it blows my mind how many people will use the space in front of a semi to change lanes, even when traffic is coming to a halt. Why do you think that big space is there in front of the 30 ton behemoth? I’ll give you a hint: it’s not for you to cut into.

So be safe out there this summer! Pay extra attention to motorcycles around you and give them a little extra room. Yes, some riders are jerks, but the vast majority of us are just out to have a little extra fun on our commute. I’ll leave you with one little story from a ride a couple years ago. I was stopped in a line of traffic when a lady came whipping up the side and tried to cut into the spot that I was occupying. Thankfully she slammed on the brakes in time but she ended up close enough that I gave her a solid pound on her window with my fist. She rolled it down and started yelling at me. I waited for her to finish, flipped open my visor and said, “After you took this spot, were you planning on calling my wife to tell her why I won’t be home for dinner?”