I agree with all the "don't see how you can do it and keep it simple", "don't see how it could prevent endos" and such. It will not be easy.

But I don't see it as a completely useless feature. It's perfectly easy to lock a front wheel with brakes if you ride on hard snow or ice. I've been among the first around here to rant and rave about the benefits of studded tyres, but they have their limits. In winter riding, brake lockout can be a real problem.

My guess is OP would be hard pressed to solve the problem and yet provide full braking power all the way up to where brakes lock. Let alone fulfill all the other promises (lightweight, prevents endos, simple to maintain, retrofittable etc). Just take a look at the current "anti-lock" spring concoctions from hell as an example of how NOT to do it. If you can do it, by all means go ahead. I'd be interested to see it.

--J