Serious under inflation of tyres is not a reason for failure however a tester may decide not to conduct a brake test if tyre damage is likely.

When using a roller brake tester the wheel not on the rollers must be braked and chocked against the reaction force. This is especially important for lightweight machines and those with small wheels.

In the case of a linked brake system, it may not be possible to apply the brake of the wheel not being tested prior to starting the test.

If a roller brake test is repeated, the chock should be removed, the machine resettled in the rollers and the chock replaced.

The retardation force of a side car brake is not to be included unless it is operated by one of the motorcycle brake controls.

The efficiency of each system operated by a single brake control is the ratio of the total retarding force generated by that system divided by the weight of the machine and rider


Most machines have two controls, one operating the front wheel brake and the other the rear wheel brake. The efficiency for front and rear wheels can then be calculated as above, (or checked by a gradient test).

Where a linked or dual system is operated by one control, the retarding force used in the efficiency calculation is the total from both wheels when operated by that control only. In this case, the other control will probably operate on one wheel. The reasons for failure 1 and 2 apply whether single or dual systems are fitted.

Motorcycles first registered on or after 1 January 1927 require two means of operating the brakes, one achieving a minimum efficiency of 30% and the other a minimum of 25%. Machines before this date are only required to have one means of operating the brakes, which shall have an efficiency of at least 30%.

The tester may know that a higher brake efficiency is normally obtainable for the model tested, although the machine has passed the performance test. In this case the owner should be advised that the braking system appears to require adjustment or repair.

Where there is doubt about the effect of a defect noted during the brake test, the tester may at their discretion, carry out a road test. (see Introduction item 10).

The assessment of bind, grab and judder in sub- sections 3.3C and 3.3D can be performed at any appropriate point during the test.

If a motor bicycle wheel locks on the operation of a brake control, the efficiency requirement of 30% is considered to have been met for that control. This does not apply to a braked wheel on a sidecar.

A. ROLLER BRAKE TEST

With the tester seated on the machine locate the front wheel in the rollers of the brake tester. Ensure that the machine is lined up in the straight ahead position and settled in the rollers. (see information column)

Select the correct direction of operation so that the wheels rotate in the forward direction.

1. Start the brake rollers and allow the front wheel to stabilise. With the rear brake fully applied (see information column) gradually apply the front brake until maximum effort is achieved or the wheel locks and slips on the rollers. Note the reading at which the maximum braking effort is achieved and release the brake.

Start the rollers, gradually increase the front brake effort to about half the maximum reading and observe the way it builds up. Hold steady and check for fluctuations. Release the brake and observe the way in which the braking effort reduces.

Move the machine forward until the rear wheel is located in the rollers. Repeat procedures 3.3A1 and 3.3A2.

Check the side car wheel brake if applicable (see information column) as in procedures 3.3A1 and 3.3A2.

2. Record the appropriate results of the brake test via the VTS Device, which will calculate the results. Where the VTS Device is unserviceable see the Introduction section paragraph 3.

1.
a. a sticking or binding brake. (see information column)

b. severe grab or judder. (see information column)

c. a braking effort that does not rise or fall in proportion to the lever or pedal force applied

d. excessive fluctuation of brake effort with steady application of the brake. (see information column).











2.

a. no brake control achieves an efficiency of 30%

b. the less effective brake control does not achieve an efficiency of 25%

(Note: this RFR is only to be applied if 1 control achieves 30% and the other control fails to achieve 25%).

c. Neither brake control achieves an efficiency of 25%