Linear Iowa safety issues

Linear Iowa safety issues

Thousands of Linears were built in Iowa before 2002. They were made in Guttenberg Iowa by Kann Mfg then Linear Mfg. from 1985 to 2001. There are lots of them out there; If you see a Linear Recumbent for sale on EBay It is probably one of these. They are generally good bikes, but have a few common problems. Here are some of the more common and significant problems we have seen.

A foldable Linear will have two quick release levers in the frame hiding under the seat.

Iowa built foldable Linear Recumbent

These known Safety Issue with Iowa Built Linear Recumbent Bicycles mostly apply to the foldable models.

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Problem: Front folding joint- UNSAFE if not secure before riding!

Applies to: All pre 2002 folding Iowa Linear Recumbent bikes.

Results in: DANGEROUS ACCIDENT!

The front of an Iowa Linear folding frame has an internal “latch”. It is invisible – you cannot see when it is safe and when it is not. Applying the front brake or hitting an obstacle (a pot hole or speed bump) can cause the front joint to suddenly fold resulting in loss of control and a potentially dangerous accident. We know of two accidents like this, one that involved a broken bone! ALWAYS be sure the front folding joint is fully inserted in the frame! (see pictures)

 

Iowa Linear front fold – fully inserted and ready to ride.

The same Linear recumbent – partially inserted and UNSAFE to ride!

Do not ride a bike in this condition.

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Problem: Iowa Built Linear rear Folding frame bending and cracking

Applies to: All pre 2002 folding Iowa Linear Recumbent bikes.

Results in: Unusable bike, repair parts not available.

The most common frame breakage problem on Iowa built Linears is in the rear folding frame. Well designed for vertical loads (like hitting a bump), it was less well designed for high chain tension from hard pedaling (like large, strong riders pedaling up a hill). High chain tension causes the rear frame to flex to the right. We have seen several rear frames that were cracked and unusable, they were all bent before cracking. If you own one of these bikes you should inspect the rear frame occasionally for alignment and cracks a few inches behind the folding joint (see pictures). We have not heard of a sudden failure causing an accident though this is possible.

Linear Manufacturing Inc, in Guttenberg Iowa, made these bikes before 2002, that company is now defunct, repair parts are not available. Iowa built Linears with triple front sprockets (instead of the 3×7 hub) seem to be more likely to this failure. Welded, non folding models are less likely to fail like this unless ridden with the rear wheel loose.

 

Badly bent Iowa Linear Recumbent rear frame.

This is so bent it was virtually un-ride-able.

 

A cracked Iowa Linear rear frame.

A frame cracked like this would fail if it continued to be ridden.

We are not aware of any accidents or injuries from this problem. Replacement rear frames are no longer available. Before you buy an Iowa made foldable linear check the alignment of the rear frame.

 

How to check the rear frame alignment of an Iowa Linear.

1) Remove the rear wheel

2) Fold the rear frame

3) Measure the distance from the right dropout to the beam, then the left. They should be the same. 1/4″ different is probably not a problem. 1″ different is probably a problem.

We remedied this on our NY built Linears by adding a horizontal horseshoe-shaped gusset on the top of the frame. This reinforcement makes the rear of the frame about 4 times more rigid than the Iowa frame in the critical dimension.

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Problem: Frame beam crack behind bottom bracket.

Applies to: Iowa built Linears with bottom bracket shells welded to the frame.

Results in: DANGEROUS ACCIDENT!

 

Iowa Linear Frame Cracked behind pedals

We know of one Iowa built LWB that cracked here. This was dangerous because it was still being ridden when the frame beam had cracked over 1/2 way through. The crack started at the bottom and grew toward the top of the frame until the frame separated in two. 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 the bottom bracket bolts to the frame the frame will not crack. welded bracket holding the bottom bracket may crack but the frame would not. 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.

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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. If this happened while you are riding it 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. This is a rare occurrence especially on newer NY built Linears which have a solid flute tube.

 

Flute tube” from a Linear Recumbent Bike.

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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.