ELECTRIC MOBILITY TRICYCLE
FRONT END REDESIGN
JOSHUA PARDOE, DANIEL LOEFSTEDT
The Problem Introduc on Imagine living in a place where daily household tasks, such as
fetching clean water, require you to travel miles on foot. Now
imagine living this life with a mobility impairment. Your mobility would be slow and difficult, likely limited to crawling on
hands and knees, and your household contributions would be
restricted. For the physically impaired living in Mahadaga,
Burkina Faso, this picture of life is a very real one.
The Mobility Tricycle Project
originated in 1999 with a hand
powered tricycle design for people
with limited mobility in Mahadaga, Burkina Faso. In 2004
there was a special request for a
tricycle that requires much less
demand on the upper body than
the hand powered tricycle and
thus the electric version of the tricycle was born. The Mobility Tricycle Project is now working to
improve and fine tune the current
hand powered and electric tricycle
models. Our goal is to produce
designs that are simple, costeffective, and locally sustainable
in Burkina Faso.
The main issue that the Front End Redesign team has been tasked with addressing is an imbalance in the handling of the electric tricycle. This imbalance causes the tricycle to pull to
the left, which significantly increases the steering force required to maneuver the tricycle. We
discovered the imbalance was caused mainly by the non-symmetrical shape of the fork, both
vertically and horizontally. The horizontal symmetry issue was solved by developing a bending tool to ensure that brand new bicycle forks are bent symmetrically. However, to deal with
the vertical non-symmetry, we needed to develop a new method of bending the forks as well
as testing the bending tool for used forks that have horizontal non-symmetry.
Centerline Offset Hand Powered Tricycle
The bicycle fork bending tool developed last year was tested to see if it would work on forks that
are not symmetrical. The procedure for this testing involved a few modification from the previous year. First, if the centerline offset is too large or the blades are too wide to fit the trike, the
blades are compressed together through the use of table clamp vice until the ends of the blades
are in line with the connection of the blades to the rest of the fork. Then, the bending tool is used
on the bicycle fork until the space in between the end of the blades is wide enough to fit on the
tricycle. This testing showed improvement on the force and we determined an allowable centerline offset tolerance of ¼ inch.
Centerline Offset
Paddle Offset
During our testing, we realized that fixing the centerline offset of the bike didn’t completely solve the
steering issues of the tricycle. We discovered something else was wrong with the bike. There was a vertical offset on many of the forks we tested. We called this the “paddle offset”. During our testing phase,
we discovered that if the “paddle offset” of the fork was larger than 1/8 inch, the straightening force required to drive the tricycle is larger than 4lbs. However, our testing showed that when the “paddle offset” is reduced to within 1/16 inch, the handling of the tricycle improves significantly, to within 1 lb of
straightening force required, and the fork can be considered symmetrical and usable for the tricycle. In
order to fix the “paddle offsets” we were finding in the many different forks, we had to develop a method to fix the problem. If there is a vertical blade offset found on the fork, then it is attached to a table
through 2 clamps (one on a blade and one on the centerpiece where the blades start) so that the ends of
blades extend past the table. Once securely clamped, a crowbar is lodged in between the blades and pulled down to apply
a twist deforming the fork until the geometry is acceptable. Paddle Offset
Fork Bending Tool
Procedure to fix the paddle offset
The height difference between hR and the
hL is the paddle offset
Electric Tricycle
Clients Conclusions The Center For The Advancement Of The Handicapped (CAH)
The widespread availability of used bicycle forks which are not symmetrical requires a procedure for
modifying these forks to regain symmetry which we were able to develop. Not only does the centerline
offset between the fork blades need to be symmetrical but also the vertical height of the blades.
Through the use of a previously developed bicycle fork tool and a method using clamps and a crowbar,
a procedure was created to modify any non-symmetrical bicycle fork to become symmetrical.
Further Informa on For more information about the Mobility Tricycle Project, please visit:
http://www.thecollaboratoryonline.org/wiki/Mobility_Tricycle_Projects
Acknowledgements A special thanks goes out to Dr. Van Dyke and John Meyer for advising this project and to Rachel
Mazurek for her work and leadership on this project.