When and if you decide to modify your motorcycle, always keep Isaac Newton in mind. No, not the cookie inventor, that was Harvey Newton, a distant cousin of Isaac’s. Isaac Newton was the physicist who discovered that “for every action, there is an opposite and equal reaction”. What does that have to do with motorcycles? I thought you’d never ask.
Here’s an example. Let’s say you’ve got a new Harley-Davidson Street Glide with the slammed rear suspension right from the factory. On that bike, the rear shocks actually lower the bike about one inch in the rear. That means the rear shocks have only two inches of travel before they bottom out. With just one 180 lb. rider on your average road, that’s not a problem. Put two people on the bike, load the bags and you’re going to have a very stiff, easy to bottom out ride.
But, you like that slammed look so much you decided to lower it even more in the back and an inch or two in the front as well. Here comes the opposite and equal reaction. Hopefully, you won’t go the cheap route and put one of those dog eared twenty five dollar gadgets that just angle the rear shocks. That will destroy the ride altogether and cause the bags to contact the shocks when you go over a bump. If you must lower the rear of the bike, invest in a good set of shocks. Yes, they are expensive, but they’re worth every penny when you hit a bump while rounding a turn at 50 mph. Up front you’ll need a matching set of springs and the proper fork oil. With all this, you’ll have a bike with a stiffer ride than stock and a very limited lean angle. That means hard parts such as the floorboard mounts will hit the ground if you get aggressive in the twisties. The bike will look great though, when parked. Whether or not it’s worth it is strictly up to you.
How about performance mod’s for the motor? Again, keep in mind that extra power comes with a price. Let’s assume you’ve had the modifications done properly and all the parts work together as designed. The drive-ability is perfect and you can feel the extra power. What’s the opposite and equal reaction? More heat from the motor. More power, more heat.
Even the simplest change such as a different seat can cause an opposite and equal reaction. Sometimes for the better. For instance, HD’s reach seat puts you closer to the bars. That’s good for a rider with shorter arms but not so good for a taller rider whose arms may be bent a bit too much. I’ve seen riders put after market lower seats on the bikes; A lower seat will put you further from the bars and along with putting your feet closer to the ground, they’ll also be closer to the floorboards. That means your knees will be bent a bit more when resting on the boards.
Then there’s custom paint. How the hell can paint cause an opposite and equal reaction? Speaking from experience, here’s what happened when I had a beautiful custom paint job done on one of my bikes. First, I never rode it to any bike nights because I was afraid of parking it and getting a scratch on that fancy paint. Second, I had to be careful of what roads I’d ride on, less a piece of gravel might be thrown up by a truck and nick the paint. When the inevitable scratch and nick did appear, it cost a small fortune to repair. I wound up not riding the bike very much and sold it a year later.
Am I telling you not to modify your bike? Of course not. What I am telling you is be aware, give some serious thought to even the simplest modifications because, “for every action, there’s an opposite and equal reaction”.