The Merlin Tree

DT Upgrade
DOUBLE TREADLE UPGRADE for your HitchHiker/RoadBug - These instructions are written for wheels made since April of 2012. Older wheels can also be upgraded but the process is more involved and wheels are best returned to The Merlin Tree for the conversion.


Remove flyer and spare bobbins. Remove two screws and finish washers just above the 2 1/4 holes. Discard the finish washers and then reinsert the screws until flush with wood surface. Insert 2 roundhead bolts into holes on left front corner of base from bottom upward. Longer bolt is to the front. Hold the treadle unit in place to help guide and center the screws in the nylon bushings. Newer units do not have the nylon bushings only holes directly through the wood.

Remove lock nut and small washer from wheel axle end. Hold wheel from turning while removing the nut.
Replace locknut and screw with the axle extension piece. Screw on so that round recess in the extension piece faces outward.

  **This step is critical for proper treadling as the two treadle attachments must be slightly off dead opposite.

Screw the crank arm extension back onto the wheel axle until snug but not restrictive of wheel rotation. With slight turning align the crank to 175 degrees or 185 degrees of the crank (footman post) on opposite side. In other words, if the right side footman post is down at 6 o'clock the left side crank end should be at 11:30 or 12:30, NOT directly opposite. When one treadle is fully down, the other treadle will be 'almost' fully up.

If the crank is not in the correct position, unscrew crank short of taking it off, tap axle back in so that the head comes out of the right side of the wheel face. Rotate axle 90 or 180 degrees and tap back in. Remember that the axle is a carriage bolt and has a square base under the head - the bolt can be put in four positions, one of which will allow the extension piece to be aligned properly.

"Hug" wheel so that you can prevent rotation and with one hand hold axle extension piece where it should be. Tighten star-ring washer/nut onto axle and to the axle extension piece with the " socket wrench.

A drop of blue Loctite may be applied onto the axle bolt before screwing on the nut to improve the grip.

Screw left footman bolt into crank end and 'snug' so that it does not loosen during operation The serrated nut on the right footman end may be replaced with the 1" knurled nut provided so that the footman ends match in appearance.


The slide-on end of the left treadle assembly may need to be sanded down slightly if it binds against the wheels wood center support.

You now have two additional lubrication points; the hinge (pre 2012) and the bronze footman sleeve.
If the drive wheel is tracking in and out after assembly it may be trued by a forceful pinch toward the center support at the point where it tracks furthest away from the center support. Doing this once or twice will correct the track of the wheel.
The upgrade kit includes:
left treadle unit fully assembled
2 round head bolts - 1-3/4", 1-1/4"
2 knurled knobs - ", 1"
crank arm extension piece (crank)
star washer/nut
You will need:
" socket wench
Phillips screw driver
small tap hammer
crescent or channel lock wrench
medium or light duty Locktite