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.

 

[Paulquattro]

Have not had a problem in 3 yrs of ownership (that's done it )
Have heard of them coming loose when people don't check them after a wheel change but not snapping them off
I will say one thing thou a 25nm torque wrench has to be a pretty good quality when your in the lower numbers to be properly accurate
I would and i do tighten everything by feel generally on my bike thou you get a good idea looking at thread sizes and thread materials what works and what doesn't when you are doing things up .