One of the more upright bikes might work- But it all depends on the Back injury. I have a compressed vertebrae and upright puts more pressure on it so I have to stretch out on the bike. Incidentally- I can be in the most severe of pain but get on the bike and ride 50 miles without a twinge. Sitting in a chair will only make it worse.
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How long was I in the army? Five foot seven.
Spike Milligan