Accossato thumb brake master cylinder BP003
02 · Data & docs

The facts.

Technical data
Part numberBP003
TypeThumb brake master cylinder
Piston diameter10.5 mm
LeverLong, no bracket
BodyCNC-worked aluminium, black oxidation
Hose fitment8 mm
PairingPair with MP005 for pedal + thumb control
Road approvalNo German approval documented
DescriptionThe whole story▼

The BP003 takes the same 10.5 mm thumb brake master cylinder used across this range and fits it with Accossato's long-reach lever instead of the short version, giving the thumb a longer stroke and more leverage over the same light piston. No mounting bracket is included, so the clamp interface is left for the rider, team or workshop to source or fabricate to suit their own bar, clip-on or perch. The longer lever is often chosen by riders with a bigger hand span or those who prefer to spread the braking effort over a longer pull rather than a short, sharp dab.

Key Features

  • 10.5 mm piston diameter for a light, easily modulated rear brake action
  • Long-reach lever for a bigger thumb span and a longer stroke
  • Supplied without a mounting bracket, for a rider-sourced clamp
  • CNC-worked aluminium body with a black hard oxidation finish
  • Suited to flat track, supermoto and adaptive hand-control use
  • 8 mm brake hose fitting matched to the piston size
  • Designed to pair with the double-ended MP005 for combined pedal and thumb braking

Construction and Material Quality

Construction follows the pattern of the rest of the Accossato thumb brake family: a CNC-worked aluminium body with a hard, black surface oxidation treatment, machined to hold the 10.5 mm piston and bore to tight tolerances so the lever gives a firm, repeatable stroke rather than a soft or inconsistent one. The long lever itself is a separate forging to the short version, shaped to extend further around the bar while still clearing the grip, and is fitted to the same body and internals as the rest of the 10.5 mm family. An 8 mm brake hose fitting is used throughout, matching the piston size.

Long-Lever Feel and Pairing Notes

A longer lever changes the geometry of the thumb stroke: for the same amount of piston travel, the thumb moves further but with proportionally less force needed at any single point along the pull, which some riders find easier to modulate smoothly over a longer dab of rear brake. It also sits the contact point further from the bar, which can suit a larger hand or a glove with thicker padding. As with the rest of the thumb brake range, Accossato does not recommend running the BP003 together with a separate rear brake master cylinder on one hydraulic circuit; riders who want to keep the pedal brake working as well should look to the double-ended MP005 instead of combining two independent master cylinders.

Fitment and Compatibility

No specific vehicle list is published for the BP003, and it is not listed against any motorcycle in our fitment data; it is a universal thumb brake master cylinder rather than a model-specific part. Before ordering, check the handlebar, clip-on or perch diameter your own bracket will need to clamp, confirm an 8 mm hose fitting suits your rear brake line, and make sure the 10.5 mm piston matches the fluid volume your rear brake system needs.

Road Approval

This master cylinder is not supplied with German road-approval documentation; it is intended for off-road, competition and adaptive hand-control use.

Scope of Delivery

The package includes the Accossato BP003 thumb brake master cylinder fitted with the long lever, in black CNC-worked aluminium. No mounting bracket is included, and the fluid reservoir and brake hose are not included and must be sourced separately.

Specifications

  • Part number: BP003
  • Type: Thumb brake master cylinder
  • Piston diameter: 10.5 mm
  • Lever: Long, no bracket
  • Body: CNC-worked aluminium, black oxidation
  • Hose fitment: 8 mm
  • Pairing: Pair with MP005 for pedal + thumb control
  • Road approval: No German approval documented
FitmentWhich bikes this fits▼
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