What brand and model cyclocomputer did you get? That information will help diagnose your problem.
I have a Cateye Astrale on my commuter and a Vetta R77 on my road bike. No problems with either.
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.