Bus from Heraklio to Chania with stop in Rethymnon

While we have never stored our bags in Rethymnon we have stored them in Chania. There were no lockers there, just a large room with an attendant. When we returned we handed the attendant our chit and we picked up our bags. I suspect it will be similar at Rethymnon.
Honestly the last thing you would want to do is rent a car and then park it in the old town area of Rethymnon. Often the trunks are small so some of your luggage will be in plain sight. If it makes sense to rent the car and drive to Chania then get the car when you are finished exploring Rethymnon.

For fun here are some images of Rethymnon
Rethymnon https://www.flickr.com/photos/stanbr54/albums/72157654700502270

Thanks Stan. Hadn't thought of that possibility. Now leaning towards not renting a car and get one only after a couple of days in Chania. We have six days planned in Chania area.

Might I suggest that you just take the bus directly to Chania and leave it at that?

My reasoning is that unless you are staying more than, say, three nights in Chania that there is much more than enough for you to do there to fill that time.

If you choose this option, do any of your other problems go away? Will you still be having an incredible time? The answer to both is emphatically "yes", so why welcome the aggravation?

Some might say, "Oh, but Rethymnon is incredible; not to be missed." Which is true, but you'll also at the same time be passing by dozens of other equally mind-blowing places and shortening your time in Chania.

Pros: Get to see Rethymon for a lil' bit.
Cons: Plenty

I rarely pass up awesome in the hopes of maybe, or maybe not, finding something awesomer.

Thats a good decision. I did not mention the fact that you do not need a rental car for the first coupe of days in Chania because you might have rented from Rethymnon. Exploring Chania old town thoroughly takes 2 days so the rental car would just be sitting there unused.
For fun here are some images of Chania.
Chania 2024 https://www.flickr.com/photos/stanbr54/albums/72177720318408008/

Chania 2022 https://www.flickr.com/photos/stanbr54/albums/72177720299646015

Skip Rethymnon and enjoy Chania!

How many nights total are you spending in Crete?

My experience isn't helpful. I spent only two night and most of 3 days in Crete, a night in Heraklion and a night in Chania. If I had given myself extra nights on Crete I would have at least spent a night in Rethymnon, and on another day gone to the Samaria gorge. I didn't rent a car.

Some people on this forum over-rate Chania by about 25% and under-rate Heraklion.

8 nights in Crete. 2 nights in Heraklio, 6 in Chania area. We did think about one more base, but a lot of our vacation is just relaxing in nice scenic places, walking through towns, enjoying food, wine, markets, etc.

We had a car and did stop in Rethymno. for about four hours. We enjoyed it very much and would like to have had more time. It is different than both Heraklion and Chania I think. But Heraklion does have a fortress too.

We went to the fortress, had lunch, and visited the folk museum which was really interesting.

You have six nights in Chania so that is more time than you will need for the city itself. We spent four nights in Chania without day trips. The question is how you want to spend your time. You will give up something else for stopping. The question is what you value more. But I think it is very doable if you decide you would like to spend your time in Rethymno.

And I agree that luggage storage is likely giving your bags to a person rather than storing in a locker.