Parallel Engineering

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Welcome To Parallel Engineering - Motorcycle Frame Alignment For All Bikes.

Parallel Engineering

Problems with Motorcycle Frames -

Road & Race.


Frames made using a jig to position components prior to welding miss a very important step in the manufacturing process - precision alignment.

The frame jigs are not accurate enough which leads to misaligned mounting brackets,  swinging-arm axis not perpendicular to the frame centre line plane and rear wheel not parallel to or in line with the frame centre line plane.

Correcting misalignment utilising an Engineers surface table is achieved through machining and fabrication - no bending involved as the problem is not bent tubes but axes and brackets out of position.

The surface table is essential as it providers the horizontal datum in the form of a plane (flat surface) from which tool makers blocks provide the vertical datum plane. 

Wheel to frame centre line is corrected to +/- 0.005" and swing-arm axis to steering head axis corrected to +/- 0.002". This is many times better than a typical classic bike e.g Norton Commando rear wheel up to ¼" out from frame centre line plus several other serious alignment issues.

Wheel to frame misalignment creates a steering bias which results in front tyre scrub (shows up as assymetric wear pattern) robs you of mph and means the engine and transmission is always working harder.

Swinging-arm axis misaligned to steering head axis results in the rear wheel moving left to right across the frame centre line as the swinging-arm moves up and down. It  can give the same symptoms as worn swinging-arm bushes.

Both the above problems create instability, inaccurate steering and bad handling.

Several classic frames have been wrongly maligned as being weak, bendy etc and has led to owners spending unnecessarily on upgrades in an attempt to improve things when what is required is precise rolling chassis alignment.

Rather than assume everything is as the designer intended it makes sense to get your frame accurately checked at Parallel Engineering.

Working to close tolerances out of square axes and wheel centre-lines are corrected to the frame centre-line. All work is life-time guaranteed.  

Problems with Frames


Solutions for Motorcycle Frames.

The following steps are required to establish complete alignment.

  • Steering head axis and swingarm axis are checked for square in two planes.
  • Swingarm axis is checked for parallel to the rear wheel axis.
  • Rear wheel is centred to frame centre line.
  • Fork stanchions and yokes are checked for parallel.
  • Front wheel centred to frame centre line.

On assembly, front and rear wheel centres and axes are now inline and square with the frame centre line and steering axis.

Simon Ratcliff B.Eng (Hons).

Parallel Engineering.


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