Rail (750Wh) Trek Rail UDH issues

[Matuk72]

So my rear mech decided to smash into my frame destroying itself and taking a nice chunk out of the frame. UDH was fine so I’d say the design isn’t that great If it’s going to cause so much damage rather than break a £20 item.
My problem is though, when trying to torque up to the specified 25nm I’m destroying the threads and the UDH are breaking in half. I’ve now broken 2 trying to torque up to what trek say should be 25nm.

Any one else had this problem?

thanks in advance for any advice.

 

[rooftiler1]

Surprised you never had any response on this one.
I've just bought one of these bikes, decided to check the torque on the UDH, and as i got to 25nm it snapped off. Seems from what I've read thats its common on Trek's which worrys me.
I have a new UDH hanger but unsure if to fit it or send the bike back as I've not even used it yet!

 

[Matuk72]

Surprised you never had any response on this one.
I've just bought one of these bikes, decided to check the torque on the UDH, and as i got to 25nm it snapped off. Seems from what I've read thats its common on Trek's which worrys me.
I have a new UDH hanger but unsure if to fit it or send the bike back as I've not even used it yet!

I’ve broken 2 with the same issue.
Rear mech smashed in half after hitting a rock. Replaced new rear mech and also got a new UDH as i couldnt tell if it was bent and thought while I’m doing the mech I might as well replace it.
As I was tightening it it snapped off, checked the torque wrench and it was ok. Got another one which did the same. I’m also using genuine trek parks not a cheaper version. I ended up taking it to a trek shop and got them to fit it.
They said it torqued up ok and have not seen any issues with this before. I really doubt that…..

Its really annoying that an expensive rear mech smashed in half before the UDH. It does seem to be a design fault on what is otherwise a fantastic bike.

 

[rooftiler1]

I’ve broken 2 with the same issue.
Rear mech smashed in half after hitting a rock. Replaced new rear mech and also got a new UDH as i couldnt tell if it was bent and thought while I’m doing the mech I might as well replace it.
As I was tightening it it snapped off, checked the torque wrench and it was ok. Got another one which did the same. I’m also using genuine trek parks not a cheaper version. I ended up taking it to a trek shop and got them to fit it.
They said it torqued up ok and have not seen any issues with this before. I really doubt that…..

Its really annoying that an expensive rear mech smashed in half before the UDH. It does seem to be a design fault on what is otherwise a fantastic bike.

I find it hard to believe the bike shop would be doing anything different unless your tool to apply the correct torque was over doing it - who knows, maybe they apply less than stated to play safe. One thing I did not realise until recently is that most torque wrenches do not apply torque anti-clockwise which is why some folks have had things snap.

It seems it has to be 25Nm to ensure the hanger behalf as design during an incident. Just seems a bit scary how the worst scenario can mean damage to many components.

Sadly I've decided to send my Rail back as I don't want to have this concern in the back of my mind.

 

[Matuk72]

I agree, I doubt the shop torque it up to 25nm. I’ve got a park tool wrench that does do reverse so I can’t think that I was doing anything wrong. If I ever need anyone I’d probably try and find an uprated UDH.

If you’re not happy then I think you’ve probably done the right thing. It’s a lot of money to spend to be not 100% on the bike.

 

[DylanJM]

I think sometimes you've got to use your best judgment on these things despite what the manual says. If you have stripped them twice while not getting a 25NM click from your torque wrench then I would just go by feel the next time. Last time I replaced a UDH I just went with what felt right (I didn't have a torque wrench available) and it has not caused me any issues. I feel like for a UDH this is a fine approach I would not necessarily do this on other components.

 

[Andrewpatti]

Same thing happened to me yesterday on my 2025 trek rail 9.7 gen 5. Set the torque wrench to 25nm and tightened it like normal and it broke the udh in half. Now I have the plastic udh sleeve, bolt and washer stuck in the frame dropout and it just freely spins. Not enough plastic sleeve sticking out to grip onto with pliers so that I can back out the bolt. Anyone had something similar happen? May be hard to tell from the photos but I think when it snapped it mushroomed the plastic sleeve a bit bigger than the hole it goes through. In theory I should be able to push or hammer it out from the back out the drive side as the plastic sleeve and bolt normally fit right through the dropout. No matter what I try I can get it to budge. I’ve seen posts online about people using a soldering iron to heat the bolt and soften the plastic then tap it out and then a few other people using a hacksaw blade from the center of the bolt In a few places then hammering it out. Not optimal. As I live in a city and am not close to any MTB shops by foot I’m going to have to figure it out myself.

(Broken udh on the left with new on the right for reference)

 

[rooftiler1]

I had this happen on a brand new Trek before I even rode it. It was loose and when I tried to tighten it, it snapped. Then realised my torque wrench did not support counter clockwise torquing. I have another digital wrench that can but only take
It to 20nm and so far no issues.

 

[Heated]

we do 17-20nm with blue loctite. never had an issue.
this was after breaking a few with a left hand specific torque wrench.