Mk IIIa

Frame

     Pretty much straight forward with this one.  I was pretty happy with the Mk III and this one is very similar.  I lowered the bottom bracket from 18" to 16", made sure the caster was 15 degrees (or as close as possible) and minor modifications to the seat frame.  This is the last trike I built, and will build, with that style of seat.  I much prefer the simpler design on the flying cross.  The handling on this trike is very nice and the steering is even more stable than the Mk III and has a nice "weight" to it.

     Additionally, the prospective new owner wanted lower handle bars that looped over and around the seat sides, similar to the Mk IV and as a result, the steering/brake arms are close to the horizontal like the Mk IV.  I won't make any more trikes with low steering/brake arms like this one and the flying cross because it's too much fiddling with the handlebars and places the controls closer to the wheels than I would like.  The rest will have arms that are at about 45 degrees relative to the ground which gives lots of room for the cockpit and steering.  The handle bars are tilted slightly forward to give more room in the cockpit, similar to the flying cross, but at less of a forward angle.

     As the BB is lower on this trike than the Mk III, I needed to move the two chain idlers up to the front near the cross member.  The upside is that I didn't need one at the rear like on the Mk III.  The chainline has good alignment and it back pedals very smoothly.

     The trike has the standard mounting tabs at the rear for racks and fenders, as well as the flag tube on the left chain stay.

Seat

     The seat is a slightly modified version of the one on the Mk IV.  It's an inch shorter at the front, with the lower and upper seat supports being moved an inch closer to the tubes ends.  This is the last seat cover I'll make where I have to cut easing contours around the seat supports.  All the rest of the covers will be just plain rectangles - fast and simple to make.  The seat has 12" of adjustment and full ability to recline.

Wheels

     The rear wheel is a 26" aluminum wheel, IRC road tire, an 8 speed cassette and a "Rapid Rise" derailleur.  The front wheels are heavy duty 20" BMX wheels with 48 spokes and 14mm axles.

Misc Hardware

     The paint job is blue powder coat.  The chain tube is ½" plastic irrigation pipe with flared ends to help guide the chain and reduce noise.  There's a mounting point for a speedo on the right front steering arm.

Specs:

Modifications:

• fenders and a rear view mirror will likely be the first orders of business

Next time . . .

more trike info as they are built

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