M-Wave Seatpost Clamp with Rack Mounts

This does exactly what I wanted to do. It's strong and fit perfectly. I saw some bad reviews about people feeling like they didn't get the proper size. Please be aware that your seatpost size IS NOT the size to get for this clamp. If you can't find your seatpost clamp size online, contact the manufacturer to ask. My seatpost is something like 27.6mm, but the clamp I needed to get was 31.8mm. As soon as I got it in the mail I checked the size and it was a perfect fit. The only other thing to consider is if your bike frame is designed and rated to handle the abuse of a rear rack and cargo. Sometimes the bike doesn't have the eyelets because it's not meant to carry cargo, so if you're not sure, contact your bike manufacturer to ask. Trek was happy to help me, and it only took a out 5 minutes to get all the info I needed to feel safe getting this and putting a rack on. In case anyone is wondering, I put this on a 2023 Trek FX Sport 6, which is a full carbon fiber frame hybrid bike that is meant to handle moderate gravel and trails. It has eyelets lower on the frame near the cassette for a rack but not on the frame near the seatpost where you'd usually have eyelets for a rear rack, so this product was exactly what I needed.

This was the exact adapter we needed to attach a rear rack on a trek hybrid 7100 multitrack (2004 model). I will upload a photo to show our set-up. The bike itself doesn't have the typical attach points, and for years, I just used a backpack to haul. But now that my tween is using my bike as a daily commuter to his school, we needed a solution for. Happy to report that this was an exact fit for our seatpost. In order to figure out the correct size, I used a flexible tape measure (like a tailor would use) and measured the circumference. (you could also do this with a narrow strip of paper and then just use a regular ruler to measure the length.) Then some math to solve for the diameter: C=2 * pi * r ==> Diameter = circumference divided by pi (3.14). Then if you need to convert inches to millimeters, multiply inches by 2.54 to get your cm, then move that decimal and voila! (There's online calculators to do all of this for you, too.) This is solid and well made piece. It was easy to install and the hardware that came with his rack threaded in perfectly.

It seems to work with no problems and was easy to install. To keep from scratching my coated seat post, I found a strip of soft plastic to wrap around the post, then fastened down the seat clamp over this plastic strip. In addition to protecting the seat post, I believe it also helps keep the clamp from slipping. It would be nice if they would include something like this with the clamp, but hey, improvisation worked fine.

My old MTB had no mounting holes for my beautiful new Axiom rear rack so I purchased this M-Wave seat post clamp with mounting holes. I was impressed to find it had been precisely milled. All the holes fit the screws properly. There is even a little ridge around the top of the clamp to insure it sits correctly on the seat post. There are 2 things to be aware of. 1. Make sure you order the correct size. You should measure the outside diameter of the bike's seat post that the clamp fits over and not the seat's post that slides into it. 2. Also safeguard the mounting screws that come with your rack. You will need them. My shorter screws fit perfectly. Now my bike is a power rig that can go anywhere!

very well made,fit like a glove & fixed the carrier issue easily.

Works great, looks great, priced great! I highly recommend this, for adding a connection point for rear racks.

My seat post measures 30.8mm in diameter. This clamp was specified to fit on a 31.8mm post. I was worried that it would be too big. Instead, it was so small I could barely fit it over my post, and had to forcibly spread the clamp. Then the bolt was too short to reach the other side. This is specified completely wrong. Junk.

Nicely crafted product. Just a technical note: To attach the Ibera Bicycle Touring Carrier Plus+ rack to this clamp, you'll need either two 20mm m5 cap screws with ca. 10mm standoff spacers or two 25mm m5 cap screws with ca. 15mm standoff spacers. (M5 is the specification for standard bike mount bolts. #10 non-metric spacers work fine.)