What do you mean mid season maintenance?
I saw my first coloured leaves last week, while heading up north last week. Yep, fall is coming and as my buddies Rich and Al say “De-nile isn’t just a river in Egypt you know”. Some people dread the season change, but I love the fall and do most of my pleasure riding in September and October. So, the amount of mileage I put on in the fall can sometimes reach the 50% mark of the years total, hence my mid season estimation. The way I look at it, autumn is when I finally start riding for pleasure, and not just economical work transportation.
Months of commuting put a special kind of wear and tear on a bike. I have, for instance, 3 turns to get into work. Interspersed with those three turns is 60 km of accelerating, decelerating, clutching and generally just going straight on the highway. The first thing that reminded me that commuting related maintenance was required was this new tendency for the bike to hunt around or weave on the highway. I quickly realized that the bike was getting trapped in the tire ruts that get sunk into major multi lane highways. Millions of cars and transports every year sink the pavement, causing these deep ruts. These ruts normally don’t capture a motorcycle due to the rounded profile of the tires, but when a tire starts to lose that profile and develop a flat spot in the middle, it wants to keep the bike straight up and down. So, when you try and get out of one of those tire ruts on the highway, the bike just tips over a little and turns itself right back in! Bikes used primarily for commuting will develop this square profile gradually, without the rider even knowing. If you look at the tire from the top, you will see the edges of the square, and know that a change is well over due. However, if you are a rider that rides mostly on two-lane blacktop, the tire will wear strangely as well, but in a slightly different way. Two lane highways are built with a crown in the middle, which slopes off to both sides of the road for the primary reason of water drainage. Here in North America, unless passing, we drive on the right side of the crown, which will cause accelerated wear on the left side of the tire. You will notice it on the front tire first as it has a smaller footprint than the rear, so it takes more wear over a smaller area. Both of these highway related wear patterns cause flat spots on the tire with corresponding “edges” on both sides of the flat. The sensation is a very unnerving lack of confidence when initiating a corner. This sensation is caused by the extra handlebar effort required to force the bike off of the flat spot, which is quickly followed by a very nervous feeling as the bike tries to balance up on these sharp “edges” midway through the turn. At the time, you can’t put your finger on why the bike feels terrible going through a corner, but perhaps now you have some ideas to think about.
Another traffic related maintenance issue is definitely the clutch. In stop and go traffic, it is common to leave the transmission in first gear and simply pull in the clutch. The vast majority of today’s street bikes use what is called a multi-friction plate type clutch. When you come to a stop and pull in the clutch, you lift the clutch’s faceplate away from the basket, allowing all the metal and friction plates to move away from each other (slightly) which disengages the crankshaft from the transmission. So now, the crank is still spinning somewhere between 1-2,000 rpm (idle speed). The crankshaft is typically meshed directly to the primary gear, which is riveted to the back of your outer clutch basket. In a street bike, the reduction here is usually between 1.5 to 2 times, which is roughly half’s the crank’s rpm. If you have ever looked at a clutch apart, you will notice that the friction plates have outer fingers on them that engage the outer clutch basket (attached to the crank), and the interspersed metal plates have inner fingers on them that locate them to the clutch’s inner basket (bolted to the transmission). So at a stop, the friction plates are spinning just under 1000 rpm and the metal plates are motionless. Heat is rising fast! The outer faceplate that lifted off of this stack of interspersed metals and frictions when you pulled in the clutch lever now returns via the clutch springs when you ease the clutch lever back out, engaging the clutch. The springs gently sandwich all of these plates together which causes even more heat from the friction. This continues as the transmission starts to turn and accelerate up until the speed of the metals match the speed of the spinning frictions. At which point the clutch lever is all the way out and the clutch basket is again spinning as one. All of this heat build-up, if unchecked in stop and go traffic, will eventually warp the metal plates and burn out your friction plates. Then, under hard acceleration, the clutch will slip (engine rev up without the bike accelerating), this will get worse until complete failure follows. Needless to say, clutch service is in order. Bikes with a hydraulic clutch to initiate this ballet of heat use a master cylinder and piston to push a rod that lifts the faceplate. This system works very smoothly and benefits from automatically adjusting each use, but a pile of heat gets absorbed into the hydraulic fluid (commonly brake fluid) during heavy clutch use. It is common for your clutch fluid to need changing more often than your front brake fluid in high use situations. If your clutch fluid overheats, you don’t really feel the lever go spongy like you would with the brake lever. However, when the fluid degrades, the faceplate doesn’t lift off the basket as far when you pull in the clutch lever. This generates even more heat, as the plates are closer together from friction, worsening both of these problems.
Don’t forget to keep a close eye on your brake pads, as commuting will burn them up too. So remember, even though your not carving up the corners, you bike is wearing out in ways you may have not even imagined.