Known Safety Issues with Old
"Iowa Built" Linear Recumbent
Bicycles
Iowa Built Linear Front folding joint
The front folding joint on all folding Linear bikes is potentially unsafe if
it is not completely inserted in the frame before being ridden. When
partially assembled hard braking or hitting an obstacle (a curb or speed
bump) can cause the front joint to unexpectedly fold. This can cause los of
control and a potentially dangerous accident. Always be sure the front of
the frame is fully inserted in the frame.
Thousands of Linears were built in Iowa before 2002. They were made in
Guttenberg Iowa by Kann Mfg then Linear Mfg. from 1984 to 2001. There are
lots of them out there; these are the Linears you see from time to time for
sale on EBay. They are generally good bikes, but have a few common problems.
Here are some of the more common and more severe problems we have seen.
Iowa Built Linear Folding model problems
The frame of the 1.0 was well designed to handle the vertical loads it
encounters while you coast down a hill. It was not as well designed for the
horizontal loads you create pedaling up a hill. By far the most common frame
problem with the Iowa built Linears is the bending and potential failure of
the rear of the folding frames.
The Iowa built folding Linears flexed sideways, to the right during hard
pedaling (up-hills & sprints.) This sometimes caused "creaking" at the
rear-folding joint. This is especially true for larger, stronger riders.
Some Iowa built folding Linears have had problems with cracks in the rear of
the frame. We have seen or heard about several that cracked and became
un-ride able. All Linears that we have seen with cracks in the rear of the
frame were permanently deformed to the right. None suddenly failed and
caused an accident that we know of though this possibility does exist. If
you own one of these bikes you should inspect it regularly for
alignment and
cracks
in the rear of the frame, a few inches behind the rear folding joint. Linear
Manufacturing Inc, in Guttenberg Iowa, made these bikes before 2002, the
company is now defunct. This problem occurs most often with Large, strong
riders who ride in hilly country. Iowa built Linears with triple front
sprockets (instead of the 3x7 hub) may be more prone to this problem. The
folding model is more likely to fail than the welded model.
We are not aware of any accidents or injuries from this problem but we know
of a lot of bikes that are no longer useable. Replacing the rear of the
frame is expensive, before you buy a used foldable linear look closely at
the alignment of the rear frame. The problem is worst with the oldest
Linears, like the one pictured. Large, strong riders have the most trouble
as they put more pressure on the pedals. Be careful, many people selling a
used Linear don’t know that it is foldable. Look for 2 quick releases going
through the frame under the seat. This problem is not nearly as common on
welded Iowa built Linears.
We have remedied this on our NY built Linears with a large horizontal
horseshoe-shaped gusset on the top of the frame. This reinforces the rear of
the frame about 4 times as rigid in the critical dimension. We have not seen
this problem with NY built folders with the factory welded horseshoe gusset.
Iowa Built Linear Flute tube safety problems
The flute tube is part of the steering linkage. It is the smaller diameter
tube with a series of holes in it. It is a bit fragile and can break at one
of the holes. It it happened while you are riding t bike this would result
in loss of control of the bike and lead to a potentially dangerous accident.
Do not ride a Linear with a bent or cracked flute tube. Straightening a bent
flute tube may weaken it. To protect your flute tube from damage do not use
it as a handle to lift the bike.
Iowa Built Linear Cracks near the bottom bracket
We only know of one LWB that cracked here but it continued to be ridden till
eventually the frame broke in half. If you have a Iowa built Linear with the
bottom bracket shell welded to the beam inspect behind the weld for cracks.
If a crack is found immediately stop riding the bike!
If your bottom bracket bolts to the frame the welded bracket holding it may
crack but I have never seen a frame break here on this type of Linear.
I have heard that the Linear Sonic SWB had this problem also. It could
happen on a Linear Mach III but I have not heard of it.
We have remedied this on our NY built Linears by adding a horizontal gusset to the frame just behind
the bottom bracket making it much stiffer and many times more durable.
Iowa Built Linear Front derailleur problems
The Iowa bikes that have front derailleurs sometimes have trouble shifting
into low gear. This is usually because the front derailleur hits its
mounting block. If you are careful you can usually file the block away and
get it to work better. Installing a longer crank axle can help also.
Newer Iowa Linears did not have a front derailleur and do not have this
problem.
We have remedied this on NY built Linears by welding the front derailleur
tube to the frame and eliminating the offending block all together.
Click here for the text from the
Iowa Linear Mach III CLWB owner’s manual.
Click here for the text from the
Iowa
Linear LWB owner’s manual.
The Bicycle Man also maintains a
selection of parts and accessories for Linear recumbent bicycles.
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