I could not tell you a single thing about the latest Trek models or why Bike A is better than Bike B. I also don't believe that someone who rides like I do really notices much of a difference between a bike that weighs 2 lbs. 2 oz. and one that weighs 2 lbs. 6 oz. ... or whatever. Can elite athletes tell when their performance is aided by a smoother gear shift or carbon fiber? Yes, probably. But I'm not that athlete.
I am a bike rider, thought, so by default I have a bit of working knowledge. And, I also have access to two bikes (three, really, but one never leaves my basement) and there are distinct differences that I thought you might be interested in ... should you be shopping for a basic bike.
I'm going to show you my road bike, a Trek Lexa S, and Jim's sport mountain bike, a Trek 3 Series 3500 ... that's been modified a little from factory stock to make it a bit more road-friendly.
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TIRES: First, notice the difference in tires:
A road bike has skinny tires, inflated to 100-120 psi. They're smooth (no nubby stuff) and they ride "hard" ... not a lot of give when you're rolling over uneven surfaces. My driveway is long, hilly and gravel. I always feel sorry for my tires on it, because they just don't handle it well. They almost skid across the loose rocks and ping a few out sideways every once in a while. They're made for pavement. Period.
Jim's tires are much wider. The original tires on his bike were very nubby. Nubby is good for mountain biking. There's give and grip for uneven terrain. But nubby is not as good for road/bike trail riding. So we've traded for smooth-and-wide tires, which require inflation of 40-80 psi.
Jim's bike will handle an off-road trail and the pavement ... well enough for me to get back and forth to work or for a 20-30 mile ride comfortably. To the contrary, my bike would SUCK on an off-road trail.
If the two bikes started at the top of the same hill together, with a rider of equal weight and proportion, my bike would go down the hill faster. How do I know? I've been the rider on the slower bike. In my unscientific brain, it's because the wider tires mean more contact with the road. More contact with the road equals more "drag" ... and if I'm wrong, don't tell Mr. Raasoch. He'd be as unimpressed with my grasp of high school physics now as he was then.
HANDLEBARS: The second most obvious difference between the two bikes is the handlebars.
Mine: Curled down, like the 10-speed of your youth. They sit lower, forcing your hands a bit more forward and lower. You have the option of holding onto the curly part, too, causing a tighter tuck. You must hold them on the curly part to brake. Your brakes are on the front, meaning your hands are palms-in when you brake. Since road riding doesn't generally require a lot of braking, sharp turns or precision control, this position is OK ... it allows you to stay in that tuck.
Now, I'm sure that there is some aerodynamic benefit to the tuck vs. non-tuck position. A wind tunnel would certainly prove that. However, the way I ride, this measurement is completely pointless. If I'm a twentieth or a tenth of a mile per hour slower because I'm riding more upright, who the hell would notice and, more importantly, who the hell would care?
FRONT FORKS: Next up, the front fork.
Mine is rigid, skinny, flat, and not all that exciting to look at. There's no give. Remember when I said my tires rode "hard?" So does the fork.
Jim's has suspension ... like a shock in your car. It's two beefy cylinders, one inside the other, to absorb bumps a bit when you go over them. When you combine this "give" with the wider, lower psi tires, you get a smoother ride on that pesky gravel in my driveway. And over the railroad tracks. Or bridges made out of old railroad ties. However, it also makes the bike heavier.
BRAKES: The other main difference between our bikes is the brakes themselves.
I have rim brakes.
Rim brakes work by simply applying pressure to the rim of the tire. The harder I squeeze my hand, the more brake I get ... it's not terribly complicated. The pads come down and apply pressure to the rim, and, voila! ... slower rotation.
Jim has a disc brake on the front.
1. In wet conditions, the holes in that ring "dry" the surface out as it's turning, allowing the pressure to work faster/better. Compare that to the squeezing of the rim on my bike ... if the rim is wet, the pads just don't work as well. Or at all.
2. The hydraulic assist allows for a smoother, more controlled/constant pressure ... not dependent on how hard I am squeezing. More controlled/constant/smoother equals faster stopping.
3. In muddy conditions, like an off-road trail, that little silver ring with holes in it is farther away from the gunk on the ground and less likely to get mucked up ... allowing better, more reliable braking. If the rim on my road bike gets muddy, the brake just can't work as well because the pads can't get to the rim, perhaps.
4. A rim brake CAN cause wear on the actual rim, which can affect tires.
So if disc brakes are so awesome, why does my fancier road bike not have them? It doesn't need them. Road bikes don't ride in mud. Road bikes don't need to brake that much ... their job is to go fast in a straight line, not twist and turn through fancy obstacles.
(Kind of the way a good Thoroughbred race horse is different from a reliable, sure-footed trail horse. One is built to go forward fast and has very little skill in anything else, no fancy footwork, no back-up or sideways walking. The other will never win a race, but will take you over streams and rocks and up and down mountains safely.)
Disc brakes also add some weight, though, again, for the kind of riding I do, that doesn't really matter.
Tomorrow, gears, pedals and seats!
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