Rode the trail starting in Osawatamie. Trail was in great shape, though some parts had a lot of leaf coverage. Despite this, no issues with surfaces or slippage. Such a peaceful trail to ride. And it flows super fast.

40 miles of outstanding trail. Rapid improvement of Flint Hills nature trail due to its designation as a state park. From Osage city to Allen the trail is 20 feet wide of crushed lime stone. From Allen to Council Grove 15 feet wide crushed lime stone with rock formations and fossils on both sides. Bathrooms,food, and water in Osage city, Allen, and Council Grove. Camping available in multiple sites along the way.

Super nice trail with crushed stone. Many on/off access points along the way. It is not busy at all. There were a few walkers & runners. There are not many roadways to cross either

Well used. I have run on the majority of this trail. Would be fine for Cycling with a hybrid, Gravel or mountain bike. The Levee portions of this trail has nice views of the river.

Path is 3/4th crushed stone when you do come across paved sections it makes you thankful. There are multiple points of entry and exit along the road. Path isn’t very scenic but still a worth while trail to explore.

Today we rode the Flint Hills Trail from Osawatomie to Ottawa and back. We had a great time and this trail is highly recommended! The trail is a "Rails to Trails" route that follows the Marais des Cygnes river, so it is predominately flat. The gravel surface is packed very light chip, so almost any type of bike will work (we rode gravel bikes). In a few places, the recent heavy rains washed away the light chip top coat and exposed the more coarse RR bed gravel below, but it is not a problem. We did not see any of the thorns etc. mentioned above in posts from previous years. The trail head is a little hard to find, and Google maps did not help. If you find the Osawatomie elementary school and then proceed down that same road about 3/4 mile further, the trail head (with some parking) is on your right. Leaving on the trail from Osawatomie, the first 6 miles are completely shaded by trees arching over the trail. After that the trail is about 1/2 shaded and 1/2 open meadows - so this is a great trail for warm summer days (and should be beautiful in the fall). There are many bridges, views of the river and wide open farmland to see along the way. Today, at 9 miles in, there was about 200 yd where water covered the trail from the big overnight thunderstorms, but this is not normal. There are no drinking water stops along the way - so bring at least 2 good sized bottles per person. There are however farm houses all along, so if you really needed help in an emergency, it is not far away. Ottawa is about 18 miles from Osawatomie and you will know that you are close when you pass under the I-35 bridge (about 2 miles to go). If you want lunch, turn left off the trail at 7th street (it is well marked), go ~1 mile south on 7th and you will hit Main street. Subway is 2 blocks to your left (9th street) on Main, or you can go to downtown and have a variety of food choices. We had a really nice ride today and hope that you can ride this trail soon too!

This is a lovely trail. I camped at Vassar Lake for a few nights and rode sections out and back each day between Council Grove and Osawatomie. Trail conditions were great for a gravel, mountain or touring bike. There are a few rough bridges, and a few patches of ballast or deep sand, but nothing that will ruin your day. My first morning I followed a coyote following a turkey for the better part of a mile. In Ottawa you can also connect to the Prairie Spirit trail, which is also nice.

I walked a section from Anderson ave to Manhattan ave S on a very windy day. Most of this section was along the river and lined with trees so the wind was not bad. Great walk. A few joggers and cyclists were out. A little city and country mixed in.The section starting at Pecan Circle was supposed to be the beginning of a scaled section of the solar system. Mercury was marked and the next marker was Saturn.????? I was disappointed but maybe it was never finished? Great trail to walk or bike along. Thanks!

This trail is not ready for prime-time.
Unlike the R-Ts that I've done (GAP, Katy, Mickelson), there are no dedicated services such as water (cisterns or pumps), bathrooms or portapotties, no mileage signage, not even signs identifying towns at crossroads. Essentially NO SERVICES. I did count four (I think) benches on the 103 miles we rode. Though I have been told this will change quickly since the State has recently taken over the trail, about a quarter of it is virtually impassable due to inappropriate maintenance, if any. That's from about five miles east of Council Grove on and off to Osage City. 2-4 inch ballast rocks are dumped on the trail without grading or filling, no gravel for miles (just dirt jeep trail), no side rails on unimproved bridges (dangerous), grading done in wet weather where the grader tread tracks have become miles of almost-highway rumble strips and, finally, trash heaps along side the trail.. A terrible riding experience. Add to that an approximate three mile detour just west of Ottawa on yucky gravel county roads (not marked on any - including TrailNet - maps, but clearly a long-term function of the trail).
Now, from Osage City east to Osawatomie is from passable to good enough, mostly on the positive side of that spectrum.
BUT, the people we met were all wonderful, great experiences at every interaction. The Cottage House in Council Grove and the Koch Guesthouse (AirBnB) in Osage City were delightful, and Jeff and Yon at the Ottawa Bike Shop were outstandingly - I mean really - helpful.
If you want to do the Flint Hills R-T, do the eastern half or wait till the state at least fixes the surface on the western side. Otherwise, it can be a miserable experience. Either way, once the trail is fixed, it's still a long way from the standards set by the nearby Katy.
Ron Gossen