Why Is My Replacement Thule Apex XT Locking Knob Hard to Thread On?

Updated 06/23/2026 | Published 06/16/2026

Question:

Hi there I have ordered this knob for replacing the broken one on my Thule apex XT 5. I got the old knob off no problem but the new one is having a hard time threading on. Any tips or advice. Thank you!

asked by: Jeffrey K

Expert Reply:

Hello Jeffrey,

I'm glad you reached out. If the old knob came off without any issues but the new Replacement Locking Knob # TH79JV is difficult to thread on, the first thing I'd check is the threaded stud on the rack itself. Sometimes a damaged thread, dirt, debris, or a small burr left behind from the broken knob can make it difficult for a new knob to start properly.

Try backing the knob off and carefully starting it again, making sure it is going on straight and not at an angle. It should thread on smoothly by hand. If it feels like it is binding right away, avoid forcing it, as that could damage the threads on the knob or the rack. It may also help to clean the exposed threads and inspect them closely for any signs of damage.

If everything appears clean and the knob still will not start correctly, feel free to send us a few photos of the threaded stud and the new knob. We'd be happy to take a closer look and help determine whether there may be an issue with the threads or the replacement part itself. You can send a picture by responding directly to the email you receive.

What kind of bikes do you ride? Do you have a favorite trail?

expert reply by: Kate F

Jeffrey K.

6/19/2026

hi Jeffrey My bike rack was the Thule Easy Fold XT. When I look on line at your Apex XT5, the locking wheel / knob looks similar if not identical. My rack dragged on pavement and wore the wheel down. The locking wheel / knob I ordered fit perfectly. The old wheel has 2 small screws to remove to take off. Also the wheel has the lock cylinder. Had to order special key from E TRailer to remove lock cylinder. If your new wheel will not thread on, is the existing threads on bold damaged. Can you get a tap n die set and apply to bolt to see if it can repair threads. good luck Don north of the 49th Etrailer was helpful and mailed products expeditiously. cheers

Kate F.

6/22/2026

@JeffreyK Great call out with the control key. You would need to purchase the Thule One-Key System Lock Cylinders - Qty 2 # TH450200, or you can try reaching out to Thule for just the control key since we no longer have it for sale by itself.

Tom G.

6/19/2026

Jeffery, I ordered the same part when my Thule hitch would no longer lock. And Thule was no help as they don’t (or won’t) sell any replacement parts. After messing with it a while I found the threaded rod that the knob screws onto was stripped. Here’s what I did. Bought a piece of threaded. rod the same diameter as the stripped one and 2 nuts that fit the rod. Remove the old knob and thread the nuts on the old rod together. Tighten them against each other and use a wrench on the 1st nut to tighten it against the second nut, Keep turning and the stripped rod will come out. Use that rod to determine the correct length of the new rod and cut to size with a hacksaw. Use the same 2 nuts together to re-install the new rod. Might want to use a bit of thread locker in the end of the rod. Put the new knob back on and you should be good to go. I also put an acorn nut on the end of the rod to keep from turning the knob too far off. So far my repair has lasted over a year and I know how to fix it next time. Good Luck.

Kate F.

6/22/2026

@TomG Thanks for sharing your detailed repair process, Tom. It is great to hear that first hand experience, glad you got it figured out!

Worked B.

6/22/2026

The nut and/or bolt is probably stripped like mine was. I bought new nuts at the hardware store (and maybe a bolt -- can't quite remember how this went together. But it wasn't straight forward. I think I had to disassemble the knob itself. It was definitely a weak point of the rack. My mom stripped her knob, but Thule warranty replaced the whole rack. The knob stripped, again, on the 2nd rack. Then, my father-in-law found the knob replacement on e-trailer, and figured out how to do it on his own -- genius. There's definitely more to it than just replacing, removing the old knob, and on with the new.