Hey folks, I'm looking for a rack for my Trek 7.5 FX. It's a 2015/16 model with rack and fender mounts.
Doesn't need a lot of capacity, for either weight or bulk. No need for a basket, panniers, etc. It might occasionally get something as large as a gallon of milk from the nearby store bunjeed to it, but it's mainly going to be for carrying repair stuff, extra layers, rain gear, etc. Maybe a water container of some kind for occasional long rides-basically just trying to escape wearing a hydration pack, particularly in hot weather.
Googling and searching Amazon, I'm seeing some very inexpensive ones that would do what I want, like this one:
Amazon.com : Ancheer Bike Cargo Racks Cycle Bicycle Commuter Rear Carrier Rack Black : Sports & Outdoors
These seatpost mounted racks seem heavy(that one lists at 712g), while many of the ones that mount to the frame are heavier still, and designed to support up to 100lbs, panniers, etc.
I'm not trying to totally weight weenie this bike(otherwise I'd have stepped up to a carbon frame to begin with), but am still very weight conscious, and would really like a lightweight aluminum wire rack that bolts to the frame mounts and doesn't require that overbuilt arm of the seatpost mount type. Just needs to be light and black.
Any suggestions? Any chance of coming in under a pound for a minimal rack?
Thanks!

I recently got this rack, and it is very lightweight:
TransIt TS-1 Rear Rack

EDIT: I just read the specs on it and saw that it is 590 grams, which is just shy of 21 oz. That surprised me, as based on the feel of it I would have guessed it was easily under a pound.

Hey, that's lighter than 712g! I'm not seeing many below 680g or so, and that's actually lighter than any I've read the specs on.
I like that Transit Trunk Bag, too. Thanks

Wally world has a great deal on a post-mounted rack. Under $11.00 for it. It is 1.4lb (weighed on my kitchen scale).
I bought one to check it out, liked it, bought another for a gift.

Schwinn Deluxe Alloy Rear Rack - Walmart.com


Edit: the picture is showing a few rubber pieces for spacing. They come with plastic tubes tho.
My post needed just one tube as a spacer. It tightens up fine too.

I also got that Transit TD-1 rack from Performance Bikes. It's a nice rack. Haven't had any complaints with it. If you have disc brakes, you want the TD-1, if not then the TS-1 works.

Here's the trunk bag I got:
https://www.amazon.com/gp/product/B00...ilpage_o05_s00
I've found that Roswheel products usually provide good value without sacrificing quality. But the Transit bag is also good. I looked at it in the store, just ended up going with the Roswheel to save money.

Check out the Trek/Bontrager racks:

Bike Racks | Cycling accessories | Equipment | Trek Bikes

Bontrager...go figure!
The Lightweight Backrack lists at 465g, very nice.

i have an Trek Interchange rack, not sure about weight but its a nice rack! Might as well keep everything Trek/Bontrager! 8-)

Yeah, Bontrager does put out some nice stuff. Great saddles, in particular, though I'm not so high on this proprietary Isoform bar and grips.

A couple sources for more traditional racks and other stuff:
Racks | SOMA Fabrications
Racks

I was not happy with the bar or grips either. Check out the Bontrager Race Lite bar.

They'll do for the time being, but a new bar and some Ergon bar end grips are definitely in this bike's future.

Currently rethinking the practicality of a bolt on rack that would only be used a very small percentage of the time. Inadvertantly chasing grams and imagining additional uses may have clouded my judgment, since a seatpost mount with a quick release for easy removal could actually be the perfect thing. That would add 0 grams most of the time, since it usually wouldn't be on the bike...

I have the Bontrager BackRack S, which weighs only slightly more than the BackRack Lightweight and costs less. The BackRack S felt lighter than the Topeak and other brand my LBS carried. My bike weighs close to 30 lbs, so I doubt I'd notice the difference. But I figured I might eventually move it to a lighter bike and convert my current bike to a full time utility hauler with a heavier rack.

But it's been a good rack, very sturdy and easy to set for my bike's compact frame. I've carried up to 40 lbs on it, between 20 lb jugs of cat litter, sacks of potatoes and other groceries. No problems. I keep a cargo net over the top so it's handy for quick errands to pick up just one bag of stuff.

If you start shopping errands with your bike you'll probably start thinking about panniers, but may not want them on full time. I used a large homebrewed trunk bag for awhile but got tired of the hassle of securing it, which could take up to 10 minutes to rig properly.

So for quick trips recently I've been using a pair of Nashbar Townie panniers. Easy on, easy off in less than a minute, and very secure, or easy to carry into the store to fill directly. These are open top, collapsible panniers intended mainly for shopping, not touring -- although they could do in a pinch in fair weather (the cordura/ripstop nylon and plastic stiffeners would hold water if it rained!). They're designed for a traditional paper sack, and are about half the height of a typical Braum's or similar paper sack (Braum's is less than a mile away and I prefer their bread and prices on ordinary fresh veggies like tomatos). Or they'll hold around four plastic bags full. I use a cargo net to hold other stuff on top of the rack, when I'm not also using a trunk bag. Great for short errands and to get the blood circulating.

A couple other manufacturers make similar shopping panniers, sold on Amazon. At least one was designed like a tote bag, including shoulder strap.

They looked pretty good but I'm satisfied with the Nashbar bags. I've ridden a few times with the empty Townie bags collapsed flat, including in stiff winds, and hardly noticed the weight although they did catch a few strong sideways gusts. Even folded flat they'll carry my rain jacket/windbreaker, spare tube and patch kit without getting bulky.

Just for reference, it takes me about 2-3 minutes to remove or install the rack. I keep the trunk bag attached to the rack all the time and just attach or remove the entire rack as needed. It's four hex screws, all very easy to get to. Not trying to talk you into sticking with your original plan... just letting you know it's not a big deal either way. Of course, it's not something I have to do that often. If it were, I'd probably be inclined to go the quick release route as you suggest.

When people buy bikes my LBS, as is typical, will add a rack .. parts 10% off, installed for you.

Ie, you should have gotten the rack at point-of-purchase.