So, I tried a cheap frame pack (small triangle shape) and the keys did not make noise, because they were stuffed in the bottom of the triangular bag. What I didn't like was that the zip was making noise.... lol

What about a long ride in the city??
I love nature, but there's nothing wrong riding in the city, too.
The sports clothes are CrossFit or similar shorts, without pockets.

I have a 95' Toyota. No key fob, just a $1.50 key. I can leave it under the truck in a magnetic box. I can slide it into the smallest seat bag. I'd reckon it's 5-7 grams.

The wife's much newer and quieter and smoother and more efficient Outback has a big ol fob. It's $300 to get replaced. It's kind of a pain in the butt. And it's not even a big fob judging by some of the cars I've rented.

Gotta say, I'm not thrilled.

Welcome to my ignore list.

A small, weird subsection of cyclists ignore the many products designed for cycling for iconoclastic reasons that I can't imagine. There are 3 pockets at the back of almost every jersey. There are casual MTB shorts with pockets. There are underseat, frame and bar bags of every shape and size.

In Die Hard...
 

https://cimg4.ibsrv.net/gimg/bikefor...3a56f499ff.jpg
Bruce Willis was able to tape a Beretta to his sweaty back with Merry Xmas packing tape. So, you might want to consider something like that for the key. In a pinch, I mean...

I've never been in a situation when I had to take my keys. What are they needed for en-route? The answer to that may provide a solution.

if I am taking my lock then I have a backpack so I can carry my lock. But in this case the OP is in sports clothes going for a ride.

I don't ride past the end of my driveway without the means to fix a flat. Keys aren't that big; you can jam one into even the fullest saddle bag. Or if I couldn't carry it, I'd just hide it in the yard somewhere.

I unlock my home with a key, but I have never had a need for that key en-route. So I ask again, why must the OP take the keys with them?

Guys, this post became must bigger than I expected. As you all see there are various points of views, other need to store their keys, others don't take keys, other never had this problem and others don't even know what keys or sports clothes are. Others see it as a potential problem - myself included - others never faced this issue. This doesn't mean one is wrong! It's just a discussion and for those that think it was not a valid question, then just see the discussion it caused.

Don't ask me for any further explanations, I don't have any. I don't see any point.

I was just wondering, hence my initial post! That's it!

FYI, I think I posted above, I've been using a small frame back and a small seat bag for this, BUT I wouldn't like them on my bike. It all comes down to preferences.

It's a discussion and I can't see how one could be right or wrong, except the haters of this post...

Winner!

I'm assuming you mean house keys;
on the cheap side:
you can carry your keys in your seat bag,
or if your shoes have laces you can lace the key onto one of your shoes,
if your shoes have straps you can buy heavy duty velcro, mount one side on the key and the other to the tongue of the shoe where the strap will go over the top of the key to help hold it;
if you don't use a saddle bag you can get either reusable zip tie or pipe cleaner and tie your key to the seat post;
Next stuff will cost more money but:
if you have a powered garage door you can see if they sell a key pad for around $35 you can place on the outside near the garage door then all you need to know is your own combination of 4 numbers to open it from the outside;
you can get a combination door lock for around $120, or a smart door lock for about $200 or a finger print scanner front door lock for about $300, these are the most expensive way to go but they're options.

Ever since a friends keys stabbed him during a crash, keys (and other sharp objects) go in the seatbag - not in jersey pockets. Always.

Huh? You are using a frame bag and seat bag, but not on your bike? Where else would you use one?

Good luck getting this straightened out.

seat bag, with the spare tube, and co2 and cash(never know when your gonna pass the ice cream shop)

I DO use them on my bike. But I am trying to find a solution without using these bags. Is it clear now?

hide them in a location only you know. ride. return and get them

Do you simply want nothing attached to the bike? Or is a very small bag OK? THey make very small saddle bags and very small stem bags.

If you have no bags at all, where would you put stuff like a spare tube or flat repair stuff?

Well, it's true, "nothing" is not an option. So, I 'd see as the minimal and more discrete solution, for someone who doesn't like stuff mounted on the bike, as one of the smallest seat bags, like you said, carrying the basics (spare tube, etc) and the keys, too.