Adjusting my insulin doses for audax rides

I've developed my own method of adjusting my insulin doses for when I'm doing long periods of exercise. I have a rather 'non standard' insulin dosing regime to start with so this method only works for me, it wouldn't be appropriate for anyone else. 

I use MDI (multiple daily injections). I have 2 insulin pens, levemir which is a long acting insulin and novorapid, a faster acting insulin. 

For days when I'm not doing a long cycle ride I inject levemir twice a day and novorapid every time i eat or drink carbohydrate. I also inject 3 units of novorapid at  9am and 9pm. These additional doses of novorapid are to prevent glucose rises at certain times of the day which are not matched by the levemir profile.

When I'm doing a long audax ride, I reduce my levemir dose on the morning of the ride to 40% of my normal dose, I inject my normal dose of novorapid with breakfast and aim to have a glucose around 5-7 at the start. I miss out my 9am novorapid dose. I still get a bit of a glucose rise mid morning so might have to do a small correction dose before the first cafe stop.  During a ride when I stop at a shop or cafe I inject 25% of my normal novorapid dose for food I eat. With such low insulin doses the limiting factor is the insulin pen which has half unit increments.

I have occasionally ridden audaxes starting at 11am in the morning. I used the same protocol but by the time I started riding my glucose was 13+ which was difficult to manage.

If I'm riding through the night I reduce my evening levemir and miss my 10pm novorapid dose.

It's taken a lot of trial and error to work this out, occasionally I get it right. The longer a ride is the more difficult it is to maintain focus on keeping my glucose in range.