to dive or not to dive?

Whats wrong with anti-dive? I see some have bypassed or spent a lot of time trying too. How come?

 

I was told that this system is not very effective even when properly serviced.

 

Anti-dive is a solution to the problem of needing at least two different damping forces in your suspension. Damping force is proportional to velocity and you want to damp out sharp bumps (higher velocity, softer suspension) while also not bottoming out when braking (lower velocity, harder suspension).

Anti-dive couples damping force to hydraulic pressure in your brake system. This way, it can be set up soft for harsh bumps, them firm up ONLY when braking to prevent diving.

Problems with this system include:
Extra hoses
No or few rebuild parts
Anti-Dive units tend to collect gunk since they are the lowest in the brake system.

Suspension has advanced to the point where you can get varying damping rates and spring forces for a non-linear curve without coupling to brake fluid pressure, in designs that are more tunable and reliable. I kept and rebuilt mine because I didn't want to have to go through the hassle of modding it.

 

Are you satisfied with the way the anti-dive performs after your rebuilt?

 

Eh, I'm not sure I know what the anti-dive is doing. I set it on a middle setting, then just went on my way. That plus progressive springs, and a heavier fork oil (can't remember now which one, maybe 15W) and I think the bike rides a bit harsh when it comes to bumpy roads, but does feel pretty planted when I take corners at speed.

Under hard braking I don't bottom out, but I haven't ridden without the anti-dive, or adjusted to find out how much of that is my suspension set-up and how much is the change in damping from anti-dive. And I'm not sure that I'm experienced enough that I could tell. Maybe something to try this spring.

One thing is for sure, it's clean as a whistle, has stainless steel lines, and isn't contaminating my brake fluid or fork oil

 

Just to make sure, are you saying that brake fluid and fork oil could contaminate each other if this device doesn't work properly?

 

No, old brake fluid contaminates new brake fluid, and old fork oil contaminates new fork oil. The problem is that there is likely 30 y/o fluid and crud settled in each system, and they don't really flush well without complete disassembly.

Also, if the crusty 30 y/o seals fail, you will have a problem. So you're options are completely overhaul, or completely remove, don't do it half way.

 

Allright, thanks a lot for these informations and advices.

I'm not ready to begin this rebuilt these days, but I will add it to my list for this spring.

 

I think for many it boils down to weighing the (questionable?) performance benefits of the system and the desire to keep the bike "original" against the added complexity and additional costs the anti-dive brings.

Tearing apart and rebuilding the AD units, while not that difficult, can be a little tedious. Also, replacement parts (should you need any) can be difficult to source.

In terms of cost, buying a replacement set of brake lines with 4 lines is considerably more expensive than a 2 line set up. I ended up keeping mine; I thought they added some character and originality to the bike as well as some marginal performance benefits.