Linear Limo 3.0 LWB USS
Recumbent Bicycle - The Engineering
The American Engineering behind
the redesign of the Linear Limo 3.0 Recumbent Bike. The Linear Limo is the
only aluminum USS LWB recumbent
bicycle Made in the USA today!
In 2002 we purchased the assets
of Linear from Iowa and began a long overdue structural redesign of the
Linear Long wheelbase recumbent. We started by buying and examining broken
pieces of Linear bikes built in Iowa between the 1980’s and 1990’s.
This Iowa frame part shows the result of lateral weakness
We took this information and combined it with computer FEA analysis of the
Iowa frame. Then we took an Iowa made Linear into the lab and measured its
vertical and lateral rigidity to verify our FEA model.
A Linear frame being tested in the lab
Then we spent 3 semesters designing the prototype of what became the Linear
Limo. This made extensive use of using computer aided FEA design.
FEA
tests show the strength of the New Linear Limo 3.0 Frame
Then we built a prototype and attached strain gauges and accelerometers to
the frame and a laptop computer behind the seat. The bike was then raced
through potholes, off curbs and up hills by a 240 lb rider. After looking at
all this info we felt confident enough to bring the bike to Bicycle Man, our
retail recumbent shop to let dozens of our customers test ride it and give
us feedback. They liked it! We loaned the prototype to a 250 lb friend who
rode it 800 miles then strapped on an additional 50 lbs of gear and rode
over 1100 miles from Maine to Georgia. He then sent this prototype back to
us for inspection. We stripped to the bare frame and inspected it for
visible damage but found nothing but cosmetic scratches. Next we had it dye
penetrant tested to find any fatigue cracks we could not see otherwise. This
certified technician’s report found that the New Linear Limo 3.0 passed
nuclear specifications with one exception. Based on his report we redesigned
this one area to eliminate the possibility of this happening on subsequent
Linears.
So now we had a prototype that:
-
Our customers
liked
-
Had survived
2000 miles, over ½ of that loaded with 300 lb of rider and gear.
We spent another
semester refining the frame design. We wanted to strengthen it a little more
and had to work out a few manufacturing details including designing and
building the tooling to build the Linear Limo 3.0.
Chris out for a ride on Linear Limo #1
Chris, the owner of Limo #1 has well over 5000 miles on it and has given us
valuable feedback from his experience. For instance, he found the rear Avid
BB-5 disk brake pads needed replacing after ~3000 miles so we now use the
BB-7 for easier adjustment and longer pad life.
Our 400 lb gorilla ready for destructive testing of a Linear
Limo frame.
Working with a Linear owner who is also a professor at Perdue we enlisted a
group of Perdue students and built a 400 lb fatigue tester. This machine
will simulate hundreds of thousands of road miles by repeatedly placing
loads up to 1200 lb on the seat and 100 lb on each pedal. We will soon begin
destructive testing of several Linear frames to see what else can be
improved.
I recently read that one of our competitors has a new frame design and is
selling the first one produced to a customer. I hope that goes well for
them, we prefer to test the design before setting it out to our customers.
We figure in the long run this is better for our customers and us.
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