I'll chime in because I've been through this myself -

Most of the ratio of fat vs glucose burnt during a ride is determined by intensity. Fat is majority burned at lower intensity, and muscle glycogen at higher intensity. Thought it's not as simple as 0-100% for either carbs or glucose. You'll burn fat and some carbs up to the point where you cannot supply the energy required by fat alone, and glycogen comes in to supply the marginal energy requirements.

The key is staying fueled enough during the day/ride, so that you can finish the ride strong, but also recognizing that weight loss is a energy balance game. A typical well-rested male has about 1500-2000 Calories worth of muscle glycogen available.

If your ride is sub FTP, and the total energy expenditure of the ride is say, 1000 Calories, you probably don't need to consume any additional energy to rebuild your glycogen stores. Studies (of which I can provide if its reallllly required) have shown that after about 24 hours your glycogen level is replenished. However, if you do a long (>50 miles) or a hard paced shorter ride, you'll need to supplement your energy reserves with mostly glucose. Rule of thumb is that you can digest up to 300 calories from food per hour, wether it be from gels, cliff bars, or dare i say, rice krispy treats!

It's a topic that I could talk about for days, but that's probably enough for now.. . If you're really interested in some evidence based studies, check out pubmed and search for terms like "glycogen restoration in male cyclist" or "fat vs glycogen consumption", or similar. You'll find a lot of work.