Not quite. Each time you start exercise there will be a small amount of lactic acid to deal with as there is a lag period before aerobic metabolism catches up to the increased demands of the exercise. This also goes for changes in intensity - aerobic metabolism is slower to adapt than anaerobic metabolism (or "glycolysis") and any transient deficits in energy supply will be made up by anaerobic breakdown of muscle glycogen to glucose. During your warm up the threshold at which these deficits occur will be lower so even relatively small increases in intensity will lead to lactate build up - depending to a certain extent on fitness levels. The body can quite happily burn glycogen aerobically for 20 to 30 minutes but for sustained activity it will preferentially burn fat which is more efficient, but even slower to get going and requiring even more oxygen. All these processes occur simultaneously to different levels, therefore it takes a while to settle into a comfortable balance . . . .. . . which is why it takes me a good 10 miles to warm up
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In my defence. I did state "
When there is a requirement for energy at a rate faster than the areobic system can provide, the additional energy is obtained from glucoze" and at no point stated that this happened at a pre-defined point in time, or did not happen at different intensity. I equally admit that I explained the effects in quite a simplistic manner, but the point I made remains true as in the situation presented by the OP there is nothing to support that during the first mile or two of a really easy warm up that you would 'suffer' from lactate acid build up, this would not happen unless the exercise undertaken was intense enough that the respiratory chain cannot keep up.
During a warm up intensity is usually at a point where the glucose is broken down and oxidized to pulvate, from which the lactate is produced at a rate which the tissues are able to remove it. If you are exceeding this enough that your tissues can not remove the excess lactate. I would suggest that you are exerting yourself, or even perhaps sprinting. As you correctly state what can be defined as exerting yourself or sprinting is debatable and dependent upon fitness levels
The OP stated "
i seem to suffer in the first mile or two with a bit of lactic acid build up...even when i take it really easy"... just so I am fully aware of your perspective I would like to know. Do you believe or have any evidence which suggests or supports suffering from lactic acid in the first mile or two of a really easy ride?
I do not wish to dispute the existence of lactic acid as we know it exists, but the suffering from it without exerting yourself which is what I disputed, your tissues can simply process limited amounts without problem.
It doesn't seem to have done me any harm, in terms of injury - although I'm probably tempting fate by typing this!
