Building the Ultimate Touring bike (blog)

Why build a bike?

Why take the time and effort to build a bike when there are so many good used bikes available?

The Ultimate bicycle would have no swing steer (long bikes) and no twitchy maneuvering (short bikes).

Long bikes are easier to handle with heavy loads (if the weight is distributed properly) than short bikes are.

All the factory bikes that I know of use the same mass-produced forks made for short bikes. This dictates that the steer angle be around 60degrees and the trail about 2”.

This produces a ‘swing steer’ effect that is harder to make the balance adjustments needed for slow speed climbing.

Most factory bikes have a weight limit. Some are flexable for no more than a 275lbs payload.

Climing hills with 350lbs on my tires aint easy.

Gears estimation,lower gears for faster cadance and lighter touch on the pedals...14-16 gear-inches are needed with 150mm cranks.

A step down gear may be needed for big wheels when pushing over 350lbs up 10% grades.

electro plating is stronger than powder coat paint.

Under seat rack n' pinion steering will give a tighter turn radius than swing steer long bikes.

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It is very difficult to find the proper bar placement with out a fit bike.

If your thighs pass up between your hands you can't turn the bars enough with out making them too wide.

I think it would be much easyer to build a bike using sterring linkage.

steering geometry calculator

I think it would be pointless to extend the trail beyond the front end of the contact patch because it would just make too much wheel flop.

This page should tell you everything else

mark stonich:

We regularly went over 50MPH, one handed, on our loaded tandem, w/1/2" trail. Steady as a motorcycle.

Gyroscopic isn't a major factor IMHO. But a wider front contact patch has significantly more self aligning torque.

If so does a smaller wheel need more trail than the large? Not on a recumbent, but on an upright a wider tire should have less trail.

Weight distribution is more important than wheelbase.

If you can't get self centering from your steering ergonomics, you may find that low trail leaves a vague feeling to the steering that's worse than resisting the wheelflop from too much trail. The only SWB I've ever ridden that handled OK had an 80 degree head angle.

Weight distribution and distance from the riders shoulders to the steering axis are what determines how well a 'bent can be made to handle. I have MWBs with wheelbases of 42" and 45" that are so stable that on steep, fast downhills I ride with one hand in my lap to reduce wind drag. They have 2/3:1/3 weight distribution, 6 and 9" of tiller with optimized handgrip orientation.

MWB = BB between 2" ahead of the front axle to 6" behind the axle. Easy to get good ergonomics and weight distribution. Once you get the BB even with or slightly behind the axle heel strike is not a problem.

I was locked into some of the geometry on this one so it could use a little more tiller and I rarely get a bit of heel strike. 42" WB

On the 2nd MWB I moved the front wheel 2" forward and used a slightly steeper head angle to eliminate heel strike and optimize tiller. I moved the rear wheel one inch back to maintain weight distribution. 45" WB

This one, built for a customer, has a shallower head angle and a 54" wheelbase. http://bikesmithdesign.com/Paul/PaulBlue.jpg

All 3 handle about the same.

Mark Stonich; BikeSmith Design & Fabrication 5349 Elliot Ave S. Minneapolis, Minnesota 55417 USA Ph. (612) 824-2372 http://bikesmithdesign.com http://mnhpva.org

SWB ideal geometry may be impossable, but this is as close as it gets. It would be easyer to build a

SWB with adjustable seat rather than the boom expanding. Look at Volae bikes. It took me over a year to deduce the easyest way to build a recumbent short wheel base bike. steering manouverability can be limited by over seat and under seat bars unless they are wide enough. Rack and pinion remote from under the seat cup will give the tightest turns. There should be 6" of pedal foot clearance, but you could get by with as little as 4" if you know how to ride these bikes.

The only other way to get good foot clearance is to shorten the wheel base and use a smlaller front wheel. The old Vission bikes work well like that. Note the ergonamic angle of the seat to crank (pedal ready to push)...50 to 60 degrees is the most dynamic.

A high crank maybe usfull for cranking backwords (page 86-88 of Bicycling Science) wich maybe an improvement, except that gravity would not help you past the dead spot and the seat angle may need to be steeper.
bike frame parts: novacycles