My husband and I will be in Chamonix for two nights in early September, traveling with another couple. Our ages are in the young 60's. We'd like to do the Lac Blanc hike that starts at the Index station and goes downhill to the lake, then further downhill to the next lift station. I'm reading that the trail is rocky and there are some uphill climbs along the way and places where you are scrambling up over rocks, so you need hiking shoes, good ankle support. We don't relish the idea of packing hiking shoes for this trip as we want to travel light with carry-on sized bags only. This is the one and only time we think we'd use those shoes in a 2 week trip. Any opinions on whether we'd do okay with athletic shoes with a good tread on the bottom?
There are a number of places in Chamonix where you can rent boots and other equipment. Here is one source: http://www.chaletlaforet.com/winter-in-chamonix/equipment-hire
If your athletic shoes have sturdy soles and grippy tread you should be fine. I just did the Tour du Mont Blanc hike (6 consecutive days of hiking 10+ miles a day, with 3000 feet of gain and loss) in a pair of low-cut Salomon hiking shoes, specifically these:
https://www.salomon.com/us/product/x-alp-spry-gtx--w.html?article=401619
I bought them in the village we reached at the end of the first day's hike, because the "mid" boots I brought were seriously bothering my ankle bone on one foot. I left the "mid" boots there, with a charity recommended by our guides. I don't think I will ever go back to ankle boots unless I am hiking in snow.
Our main guide wore the same low Salomon shoes, and the assistant guide wore something slightly lighter.
The trails aren't horrible, virtually any walking shoe will work but I'd want something that has some support and some grip on the bottom, bonus if it's at least water resistant in case you get rain.
With respect to Lola ; I would consider those linked Hiking Shoes not athletic shoes as I imagine the OP is talking about.
Lola's point is a good one though, that type of shoe linked is all you would need and does not take up much room and may even replace the other athletic shoes you were thinking of bringing.
Go to your nearest REI store and you will see plenty of options like those.
If you are talking regular sneakers I would not recommend it but of course people do it.
I've done this walk several times and yes, athletic shoes with sturdy bottoms should be fine. That's what I wore last time I did it and it was fine. It is quite rocky but it isn't a very long hike.
I was just there with the intention of hiking something similar to your hike. I didn’t bring my boots because of the weight, but intended to use my keens with heavy socks.
I never hiked in my 2 full days there because the altitude got to me and I was just too tired from many stair climbing and walking 4 days in Paris. I really was afraid of having an accident and I was traveling alone. The altitude had me sucking wind at all lift stops, not just the highest ones. I am 57, in reasonable aerobic shape, but overweight. The weather was not good enough for a hike because in August 13 i experienced rain, snow, clouds, sun, breezy all on the same day! I did do the river trail to get to the lift in a nearby town, but obviously that is a flat trail. I saw the hang gliders take off from the top of that lift in Brevant, which was so cool.
I like the suggestion of renting the boots, and if I hiked I would have done that and rented the poles too. That gives you much more options and won’t leave you annoyed at carrying extra weight if weather doesn’t cooperate.