Join Date: Dec 2013
Location: Puget Sound, and Allegheny County (PA)
brake which wheel? when? how?
By the time I'm fully turning, I want the bike at the speed which I intend to maintain through the rest of the turn. This is because I want the fore/aft downward force distribution to match the fore/aft mass distribution, which then yields the same ratio of required turning traction to normal force on each contact patch. (Given the same rubber compound and pavement condition at each patch, this match then provides the same traction margin for each wheel.) Anything which reduces downward force on one patch or the other, such as deceleration or acceleration, is going to reduce traction margin over that available at steady speed.
Now, getting to this thread's topic: It really does not matter how you reduce speed while approaching a turn as long as speed is steady through the turn and the suspension has had a chance to stabilize before the bike is fully leaned.
I find that the rear brake is a little better than the front during the entry and initial partial lean, because it seems to disturb the fore/aft weight distribution less. I also find that engine braking alone is frequently enough, probably because most turns can be safely taken near the speed limit and I've been trying to avoid fuzz interactions. I doubt there is any real difference between engine braking and getting the same deceleration from the rear brake.
If the topic is the best brake(s) to use well into a turn (when fully leaned), or so late in the approach that the suspension will not timely settle to that equal traction margin condition, then I would say: (1) You're doing it wrong; and (2) Do whatever produces least motion of the suspension. (Looking at the physics, I see no reason to believe that, for the same deceleration, braking one wheel will produce less torque upon the bike/rider system than braking the other. They both act with the same moment arm on the same center of mass.)
More important for any pre-turn braking than which mechanism to use is how it is done. If enough late braking is needed for it to matter at all, then a non-jerky release (and perhaps application) will better maintain the optimal fore/aft weight distribution, giving the most traction margin.