Bicycle Brake Reaction Distance means the distance a bicycle travels, prior to applying the brakes, whilst a cyclist -

sees a danger ahead;

perceives what it means;

decides on a response; and

instigates that response by applying the brakes.

A cyclist who is concentrating will have a Brake Reaction Time of about 2 seconds to apply his/her brake levers in an emergency situation.  By using the Bicycle Brake Stop Calculator, if the cyclist is travelling at 40 km p/h which equates to 11.11 metres p/s, the Bicycle Brake Response Distance would be 27.78m.

A Bicycle Brake Reaction Time of 2 seconds, which has been used in Guide for the development of bicycle facilities by the 'American Association of state highway and transportation officials', is the mode Bicycle Brake Reaction Time used in most bicycle modelling.

The following is the Federal Requirement for bicycle stopping distance with a hand brake.  It is in 16 CFR 1512.5.  Hope it helps.

(1) Stopping distance. A bicycle
equipped with only handbrakes shall be
tested for stopping distance by a rider
of at least 68.1 kg (150 lb) weight in accordance
with the performance test,
1512.18(d)(2) (v) and (vi), and shall have
a stopping distance of no greater than
4.57 m (15 ft) from the actual test speed
as determined by the equivalent
ground speed specified in

Nigel Waterhouse & Associates
Aeronautical Consulting Engineers


On a two wheeled vehicle, you cannot jam the brakes on for a 'full' in an emergency stop.
You have to achieve weight transfer first. This means an initial gentle application of the brake before a big squeeze. If you jam them on instantaneously without moving the body weigh backwards, ideally over the seat, the front end can go out from under you, particularly if you have powerful brakes like hydros.
Also on a bike, when braking heavily you'll find that you subconsciously lift off the brakes momentarily as you cross bumps etc on the road surface (eg cracks, manhole covers etc). This is to stop the wheel locking as it is unweighted over the bumps. In a car this isn't necessary.