) They don't work very well. Here's a cheap, MS-Painted simplified diagram of my current setup:<img src="http://img176.imageshack.us/img176/1747/cheapoct5.gif">
There are two pieces of metal that anchor at one end. Each has a cable attached to the opposite end. The one on the left (if you're sitting on it, or looking at the back tire from behind) has a screw/nut which holds the main brake cable. The other ends in this cheap clip thing that secures to the main cable with a screw. The red arrows indicate how force from the brake lever is distributed through the system. Obviously it will stop eventually, becasue otherwise they would not sell bicycles equipped with this setup. The Achille's Heel of this system is just how weak it is. Once the calipers pass a certain point, the force from the cable will pull more up, against the nut at the base, rather than against the brake pad and wheel rim. This is just wasted energy.
Not only is it wasteful, but it's also dangerous. This DOES NOT STOP WHEN GOING DOWNHILL! I learned that the hard way. That was really damn scary, because I was on a long hill and I had to avoid hitting a kid on a big wheel. Basically I pulled both brakes as hard as I could, snapping the front cable, and I had to slam my feet on the ground. Thankfully I didn't run the tyke over. This was unnecessary, especially since I was only doing 15-20 MPH at the time...
Here's a diagram of one of my friends' bike brakes (also cheaply rendered in MS Paint).
<img src="http://img74.imageshack.us/img74/1501/iwanttheseyj7.png">
This is a much better setup because all the cable force is directed at pulling the tops of the calipers toward each other. This is the setup I want to install. (Well, anything is better than the cheapo junk I have now...) It's a lot stronger and safer.
I took some pictures and brought them to the local bike shop. (They mostly sell $200+ bikes there.) I told the guy behind the counter my problem, and told him exactly what I wanted: the calipers and that's it. They could have sold me the calipers and let me on my way. No. He said stuff like "Bring it by tomorrow and the repair guy will give you an estimate", "We'll have to install them. Because." and "are you sure you want to put money into a Magna?" (That's what my bike is, a $90 Magna from Target). When I repeatedly told him I wanted to just buy the parts and install them myself, he gave me that <img src="http://skytroniks.com/images/database/smilies/wtf.gif"> look. (I bet he thought I couldn't do it, since I'm 19. If I can re-pack the bearings in a car I can install a lousy pair of brake calipers on a bicycle.
)Here's what he told me needed to be replaced
- The brake handle (because the stock one is plastic. I've broken more brake cables with plastic handles than I can count.
)- The handle perch (to go with the new one)
- The brake cable (because the existing ones are stock and a department store replacement)
- The calipers (duh)
- The mounting bracket (<img src="http://skytroniks.com/images/database/smilies/wtf.gif"> WTF indeed, mine's universal.)
- The brake pads (even though I bought some decent, upgraded replacements from them 6 months ago, and I TOLD HIM THAT)
Basically he said everything about the existing brake system is garbage and needs to be replaced. I think they're just trying to sucker me into buying more parts. I've had crappier secondhand bikes with brake systems that have good calipers that stop better than this bike did when it was new.
In short, they seem reluctant to just sell me parts. Maybe because the guy who was there must have fillings that are older than I am... Who knows.
My bike is a Magna, and as I said before I bought it at Target for $90 on sale. The brakes have been tweaked a lot but they don't work any better. My friend's bike is a Shwinn. It came with the better calipers. Granted, Magnas are the economy car's equivelant in bicycles, but like their automotive counterparts they'll last just like anything else if you keep up with maintenance.
I'm looking for confirmation here: Do I really NEED to replace the entire system? I don't think so. I'm not sure if anyone here has a clue about this stuff, but it doesn't hurt to try.
All the mounting points look the same on this bike, my friend's, my dad's and every other bike I've ever seen. I see no reason why I can't just replace the two rear calipers and be done with it.Part question, part rant post over. Congratulations if you read the whole thing.
. Not to mention the amount or kinds of bikes, like my OCC StingRay I got for $45 at the flea market.
With the existing set, even with softer pads, I can squeze the handles as hard as I can without braking anything and still pedal relatively easily (no worse than when I tried to pull a red wagon with stuff in it behind my 20" single speed when I was a kid...).
