Given some of the recent threads on here recently it is a pleasant to see some of the more positive side of people coming out in this one. 🙂 The thing is, going back to the OP, I would imagine most people think lots of things. One part will probably be an observation on the size or otherwise of the person (along with associated thoughts of "Wayhay, what a porker", followed by "glad I'm not that size" followed by "Motivation to make sure I don't get that size" and then "wonder how much grief the frame / brakes / bottom bracket is getting"). One part will be the typical humour side of things and general fattist thoughts. One part will a look at the bike and what it is you are riding (surprised at the lack of general Marin comments on this thread – how things have changed!)And one part will be admiration for committing to getting out and doing something that you clearly enjoy and wishing you all the best in doing it.
Out loud, and to your face, you will get a genuine and friendly, "Hi" or "morning / afternoon". If it gets a friendly response back and we are at a pause then probably quite happily have a chat about where you are riding, how it's going, how's the bike etc.
The thing with our society is that almost whoever and whatever you are there will be someone who will have a negative comment to make about you. So what. Make sure you are happy and comfortable with who you are and it becomes quite easy to ignore them. Having friends also helps. 🙂
Anyway, in a non patronising way, good for you and well done for sticking with it. Clearly you have the motivation to continue doing it because it serves a purpose in your goal of losing some weight, but that you also enjoy it. Sooooo much easier to work on fitness and weight loss activities when you actually enjoy them.