Rail (625Wh) Back wheel issue.

[Dan91]

Hey guys, has anyone had any problems with back wheels bontrager hub? Mine keeps coming loose had it back to the shop 4 times and now loose again. All they do is tighten it with the cone spanner but just seems to come loose after every ride. Its the side with the disk that feels most loose when I take the wheel off. Anyone got any ideas how to solve?

Many thanks

 

[TangoCharlie]

Hey guys, has anyone had any problems with back wheels bontrager hub? Mine keeps coming loose had it back to the shop 4 times and now loose again. All they do is tighten it with the cone spanner but just seems to come loose after every ride. Its the side with the disk that feels most loose when I take the wheel off. Anyone got any ideas how to solve?

Many thanks

I have 2022 Trek Rail 5, the rear wheel bearings keep coming loose allowing the wheel to “wobble”. It has fixed three times in about 300km of lite use. First time just after I brought it, the bike shop just tighten up the bearings. Second time I took it to another shop who found there was zero grease in one side of the bearings and they were damaged, so they were replaced and greased. Came loose agin in less than 100km. Might need to look at another hub / wheel.
FYI I’m old and 95kgs…

 

[steve_sordy]

I don't have a Rail, but I did have problems with rear wheel axles coming loose (and shock mounting bolts) on a Focus Jam2. A bit of Loctite Blue on the threads sorted that out. Make sure the threads are clean (male and female) before using the Loctite. Loctite Blue is not an adhesive, more of an anti-shake product, so you can still undo the bolt later.

 

[Mikerb]

There are 2 separate potential issues here. As @steve_sordy mentioned above the thru axle may be coming loose.......although if that is the case it usually means the sealed bearings are shot and therefore binding on the thru axle. If on the other hand it is the pre load applied to the hub axle (not the thru axle) that is coming loose there are 2 methods of achieving that ( light) pre load.........end caps or cone nuts. Since you mention one LBS merely tightened a cone nut I assume the set up you have is a cone nut plus locknut on the disc side and a reverse thread cone nut on the drive side? If the cone nuts are coming loose then the problem is likely in the freehub bearings. I have read other reports stating that the Bontrager freehub is poorly sealed. My guess is the axle is binding on the freehub bearings due to ingress of dirt/dust etc.

 

[idunne]

i have just checked mine trek rail 2022....theres a little bit of play in rear wheel

 

[TangoCharlie]

The Trek Rail Rear Hub doesn’t use sealed bearings, rather very small individual ball bearings that run in a greased race. In my case the factory had failed to apply any grease on one side of the hub so the balls were running in the race without any lube, which stuffed them. They were replaced but the wheel began to wobble again after one gentle ride!
I haven’t ridden if since they tightened the cone nuts, but will report back after the next ride.

 

[Mikerb]

whether cone bearings or cartridge the set up is basically the same. With both bearing types the axle needs to be adjusted to remove any sideplay. The only difference being that cone bearings often need some minor adjustment after a few miles of use after the hub is built because some grease gets displaced and allows a little play. that does not happen with cartridge bearings unless too much grease was added to the face of the bearings when built. Other than that the grease is of course captive within the sealed bearing.
The axle cone nut adjusters nor the thru axle should come loose however. That is a sign that the rotation of the wheel/hub is not free to rotate without binding on the axle (or thru axle). The cause is either a bent axle, deformed hub or seized/semi seized bearings.