I am going to Guatemala biking for my 50th birthday and we change planes in Miami. I have one speeding conviction on my licence can I still just get an ESTA visa or do I have to get a proper visa? Reading the application form for ESTA i believe I can but would welcome advice.
Many thanks.

it’s fine just ignore the speeding fine

Oh, and make sure you only use the official US Gov site for your application
https://esta.cbp.dhs.gov/esta/

IIRC if you read the question (I don’t remember the exact text) it asks about convictions that involve moral turpitude, drugs or X years’ imprisonment. The speeding offence doesn’t fall in those categories.

But more importantly – you have to leave quite a while for transiting at Miami airport because (stupidly) you have to clear US customs and immigration.