The Good: Perfect geometry for every style of riding, from trails to street. 3D downtube gusset not only looks awesome but definitely strengthens the front end. The headtube badge is straight up beautiful. Larger 1-3/8" diameter top tube looks strong and awesome. No unnecessary top tube gusset, which makes it look really clean. The top tube remains round at the seat tube, and the seat stays meet each other rather than overlapping the top tube, which increases strength. Larger diameter chainstays for strength and stiffness. Post weld machining on the bottom bracket and headtube for a perfect bearing fit; they went in perfectly. Mid bottom bracket, no unnecessarily small Spanish bottom bracket. Strong dropouts with more weld contact with the stays than normal. Non-integrated seat clamp looks better and clamps better than an integrated clamp. Chainstay brakes look awesome and feel even better. Extra cable guide removes the need for an ugly velcro strap or zip tie. No gyro holes for a really clean look. Basically, just a stiff, strong, functional frame that still weighs in at only 5 lbs.
The Bad: Can't get a perfect chainline with a 30T sprocket. On a trails frame, I expect at least the clearance for a 30T and a perfect chainline. I would prefer a chainstay wishbone for increased strength and stiffness, but I understand why this isn't done.
I have the newest version of this frame, the one with the new headtube badge and non-integrated seat clamp. I got it a few weeks ago and I've been riding it a lot since I got it. I have a 21" in dark green.
This is by far the best frame I've ever ridden. It feels super stable in the air and when you're bombing hills, but is still easy to maneuver and throw around. I ride mostly trails but also a lot of concrete parks and some street, and it works out absolutely perfectly for all of that. I was afraid the 74 degree headtube would be too mellow, but it's actually perfect. It feels more responsive than you think, but is still beyond stable. It made me way more confident in going fast and going over rough terrain. It makes you feel like you have a lot more control over your bike. The 11.625" bottom bracket height feels perfect for everything, not so low that you feel trapped in your bike, but not so high that you feel hunched over and unstable. The 9" standover height and 71 degree seat tube angle feel perfect and it feels like a real bike, unlike frames with lower standovers which can feel like scooters. It helps add to the stability of the frame. The 13.875" slammed rear end is perfect as well. I run my wheel at 14" and it feels awesome. Stable but still more responsive than you would think. Short rear ends are overrated.
I love the beefier tubing on this frame. The 1-3/8" top tube looks awesome and makes me feel like my bike is even stronger. It's reassuring to look down and see it, whereas on other frames you would see a 1-1/4" tube, sometimes even tapering to 1". Small tubes don't give me much confidence in my bike. Also, I really like how they chose to not include a top tube gusset. I believe top tube gussets are pointless, and without one it really looks awesome. The large 3D gusset on the 1-3/8" down tube looks awesome and definitely strengthens the front end. It's much better than the typical flat gussets on most other frames. The head tube looks clean and the lack of gyro holes makes it look even better. It's important to note FBM uses a slightly taller head tube, so be careful if you cut down your steerer tube. The headtube badge looks seriously awesome. One of my favorite features of this frame. I can't even really explain how incredible it looks. Seriously, just buy one so you can see it.
The chainstays are a larger 7/8" diameter at the bottom bracket and taper to 5/8" at the dropouts, and are .049" thick. The larger diameter definitely makes the rear end feel stiffer and stronger, which is really important to me. The chainstays are supported by a slightly larger 3/4" bridge, which helps increase the stiffness even more. The chainstays are where my one (Or maybe two? Whatever.) complaints are. I have to use 3 spacers to get my 30T sprocket to clear, and even then it's practically touching the frame. On a trails-oriented frame, I expect at least the clearance for a 30T with a perfect chainline. Also, I would have liked to have seen a chainstay wishbone, although I realize these are more difficult and more expensive to make so I can understand why they chose not to go with it. The seatstays are 3/4" diameter at the seat tube and taper to 5/8" at the dropouts and are .035" thick. They are supported by a 5/8" diameter tube bridge, which looks very nice and makes the frame feel stiffer than a plate bridge. Also, the top tube is kept round at the seat tube, and the seat stays are tucked in and make a really nice junction. This should be stronger than a top tube that is flared with overlapping seat stays. The seat tube has a traditionally cut top, which means you will need to use this thing you've never head of, a separate seat clamp. Separate seat clamps weigh less than the normal integrated seat clamp, look better, and clamp much much better. It's all around better, and should be the standard. Integrated seat clamps should go extinct.
FBM machines their bottom bracket and headtube after welding to make sure they are perfectly round, something which some people might not know. My bearings went in absolutely perfectly. If you know the story about my other frame made by the other American manufacturer, you would know that they didn't do a great job with this. In fact, that frame was unusable. However, FBM is capable of making an awesome frame, so I didn't have this problem. The integrated headtube is, of course, the current standard. Also, I really like the Mid bottom bracket they use. My previously mentioned defective frame had a Spanish bottom bracket. Spanish ends up weighing nearly the same as a Mid bottom bracket, and the bearings are so much more fragile. I definitely prefer the Mid bottom bracket. Death to Spanish bottom brackets!
The dropouts are 3/16" thick and are heat treated. They look awesome and are functional. They are well thought out and are very strong. I run a Tree rear hub, and the larger collar slightly hangs past the bottom of the dropout, but this is just a very small thing that you won't notice when you're riding. The dropouts have more contact with the stays than normal, which makes for a stronger junction. The dropouts also have plenty of room to adjust. On the previously mentioned defective frame from another American manufacturer, the dropout welds were TERRIBLE. It looks like they just gave up when they reached the back of the frame. The same can't be said about FBM's frame. The dropout welds look awesome.In fact, all of the welds on this frame are awesome, which is a welcome change from the other defective frame. Overall, the dropouts are strong and look awesome.
The brake mounts. Man, I love these. They're welded on the chainstays, which makes your brakes work better than if they were on the seat stays. It also looks really cool. A minor downside is it's a bit more tricky to put it all together since you have to put your brakes on before your chain, but it's not a huge deal. My brakes feel incredibly stiff and smooth and are extremely powerful, due in part to the chainstay located brake mounts. Seat stay mounts are cool and all, but chainstay mounts are just better. Also, welded mounts flex WAY less and are so much easier than their TERRIBLE removable counterparts. The threaded cable stop is awesome, and much better than other companies' non-threaded cable stops, which are just more difficult to use and pretty pointless actually. Also, FBM's use of an extra cable guide is AWESOME. It stops your cable from slapping your frame without needing to use an ugly zip tie or velcro strap. Another one of my favorite features of this frame.
Overall, this is the best American made frame you can get, and definitely one of the best frames you can get overall. If you are a man and you ride like a man, you'll get one.