John Cutler
One of the cranks on the second N mogul I have converted apparently became loose. I discovered the cause was not the crank loosening but the crankpin rotating relative to the wheel! The result is the centre driver had to be dismantled and replaced. Ugh.
The remaining drivers had been quartered with a GW wheel press. This is not an option for the centre driver as the 8mm long crankpin is too long for the press to accept. So the only solution is to quarter by eye. After reducing the AG axle to length (22mm =16.7mm BB+ 5.1mm wheel widths + 0.2mm end protrusions), it was fixed with one wheel in a small vice. The other wheel is loosely fitted about 1mm into the axle at approximately 90 ̊. A piece of Sellotape is fitted along the along the line of the crankpin and the axle centre of this wheel to protrude beyond the tyre; this acts as a sighting marker so needs care. This is easy to place where a spoke is directly opposite the crankpin, as in this case. The fixed wheel needs to be set on the level with its crank at bottom dead centre. Then the loose wheel should be gently rotated so that the Sellotape is horizontal. A small mirror helps confirm all is level and square. Once happy, press the wheels together in the vice with a BB gauge in place.
I found it surprisingly difficult to accurately position the fixed wheel at bottom dead centre. If there are spokes at 90 ̊ to the crankpin, then a piece of Sellotape across these can help the eye. This is not the case here. Fortunately there is a spoke opposite the crankpin, so setting this at vertical is the solution. Sighting this is confusing because of the spokes on the wheel behind, so a piece of white paper is used to temporarily blank these out of sight until the fixed wheel is in the required position.
