Let's ignore the question, for a moment, of should I install a lock mount on my new TCR Advanced. But assume that I want to.

Given that the frame is carbon fiber, should I be worried about the forces the mount clamp will apply to it? Should I be worried about the (perhaps unusual/unplanned) stresses the lock and mount will apply to the seat tube while I'm riding?

If we take it as a given that I want to have my lock mounted on the bike (and not in my bag), is there a better suggestion on how to do so than to use this on the seat tube?

  • Put your lock in your back pocket instead. The tubes can probably handle the load just fine, but you never know. Nov 8, 2010 at 18:56
  • I'd do what @darkcanuck suggests, or maybe... I see seatpost racks on carbon bikes all the time, presumably ones that have aluminum seatposts. If you run one of those, I'd find a way to attach the lock to the bottom of the rack. (Not making this an answer because I don't really know much about carbon.) Nov 10, 2010 at 2:33
  • My ex had a bike lock mounted on his carbon bike. He had it under his seat and it never caused issues for him. However, I have been told multiple times that this is a big no, no and my ex is not necessarily the most knowledgeable when it comes to bike safety.
    – user10830
    Apr 7, 2014 at 23:19

2 Answers 2


I've mounted lights with similar clamps on carbon forks with no ill effect (just have to be very careful not to over-tighten the clamp) but a lock -- which is heavy -- might put a too much torque on such a small clamp. Maybe if you could spread out the area over which the clamp attaches to the frame then it might be ok.

What about attaching the U-lock behind the seat? Hang two loops (tie wraps, wire, string, etc.) from the seat rails and pass the straight portion of the lock through them. Then secure the bottom of the "U" to the back of the seat post with a velcro strap (put some padding between the lock and the frame so that the lock doesn't bounce and scrape the seat post up).

  • Trying this, using a set of clamps from twofish. It holds okay, and seems stable enough. Just a bit too much of a hassle to put it on and take it off the bike. We'll see if I get used to it, or just end up leaving it in my bag.
    – zigdon
    Jan 3, 2011 at 18:55

I assume you mean clamping it to the top, hanging down? With the consideration for proper tightening (@dark) aside, I might have less concern if the lock were mounted on the front tube, facing in with the clamp to the top and the weight distributed evenly as space allows.

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