Suspension set up

[dmiller21283]

Hey guys. This is my first post on the tech forum. This isn't really a question about setup for track riding, so if this is inappropriate for this forum, I apologize.

My bike is a 2002 Yamaha Fz1.

I was riding on some mountain roads over the weekend with some pretty wicked switch backs. My first problem I had was when I overheated my back brake. I know the front brake does most of the braking, but apparently I was stomping on the rear brake too much. Once I lost that brake, all I could do was use the front brake. Then I noticed that when I hit the front brake, my front end felt like it was diving hard. My suspension is adjustable. I can adjust the preload, compression damping, and rebound damping on the front and rear.

1) Am I relying on my back brake to much? (normally, I apply the brakes together when I'm riding on less demanding roads. Perhaps why I never noticed the nose dive.)
2) How should I adjust my suspension? (I know a lot of adjustment is preference, but I feel like the front end should be a bit stiffer)

 

[FZ1guy]

Discussing the usage of the back brake is like asking which oil is best. Personally, I rarely use the back brake. You did not mention your weight, but if you're over 175 or so, the FZ1 really benefits from a stiffer spring, heavier oil, or my favorite trick, slightly overfilling with oil to decrease the air space. I think this would work for you, given your description. It also sounds like you should look at some better brake pads. Try a HH Sintered pad, I like EBC and Vesrah pads.

 

[dmiller21283]

My weight is about 190 (200 with gear). I just changed fork oil with manufacturer recommended 30W. I can adjust the preload to make the front springs stiffer. There are 6 position markers on the adjuster. I'm using the original setting which is position 2.

 

[Otto Man]

Your back brake is a supplemental brake and not designed for primary braking duties, which is why you cooked the back brake. Smaller brake rotor means less heat dissipation, which leads to increase brake fluid temps, faster. And the caliper is much smaller than the front, so you have less braking power...and less brake pad surface area for friction...all which adds up to why depending on the rear brake for your primary braking duties is a bad choice.

Like FZ1guy said, your springs are most likely under sprung (Typical of Jap bikes and an average American person weight) from the factory. You will always get some degree of fork dive under braking, even with a properly set up front end for your weight/riding style. However, you can still mitigate the fork dive by smooth application of the front brake and not stabbing or grabbing at the front brakes.

You don't use preload to stiffen the springs. There is no way to stiffen a spring, short of replacing it with another spring rated for a higher weight. Again, like FZ1guy said, you may be able to help prevent bottoming out the forks by adding fork oil, but there is no substitute for having the correct fork springs for your weight/riding pace.

 

[dmiller21283]

Right, I knew preload doesn't stiffen the springs. I guess I meant stiffen the front end by reducing the travel of the springs since they would be compressed further to start with. Would that be a more accurate statement? Anyway, thanks for the tips.

 

[vinny337]

Dmiller,
In addition to the other comments, the first thing you need to do is get your geometry set, then get your sag setup, then adjust our damping (rebound and compression) settings. Be sure to document everything, so when you make adjustments you can refer to your notes.