I like to take a lock out on my one-person countryside trips as it gives some good flexibility, e.g. the ability to stop at a shop with easy of mind.

However, since I changed bike to a Trek FX-3 XL and got a Kryptonite Kryptolock with the Transit Flexframe-U Bracket, I found that it won't fit inside the frame together with the two bottles I also need to carry: when placed in parallel with the frame, either the lock or one of the bottles gets locked in.

The position of the bottles is basically fixed on vertical and bottom tubes because that's where I have holes on the frames to attach the cages, and I've had enough of strap frame mounts falling off from my previous bike.

Is there a way to make it work, hopefully without using another carrier?


  • noise: it has to be quite silent otherwise it will spoil the countryside
  • leg clearance: it can't hit my leg as I pedal obviously!
  • center of mass: the lower to the ground and further back the better

7 Answers 7


Consider downgrading your security for out of city rides. Use a reasonable quality coiled cable lock for your stops. Small, light and silent.

While most cable locks can be chopped in seconds with a set of bolt cutters IMO that’s not the risk you need to protect against. You’re looking to protect against the local opportunist who might be wandering past vs professional/organised bike thieves.

The security level you need in city & urban areas is not the same security you need for a rural grocery/pub stop.

This approach does mean you need remember to swap out your lock when back in town.


If there is a solution with the bracket you have, it's likely to be on the seat tube. It's a large bike with low cage mounts on the seat tube, so this will probably work, though it depends on how well you can get everything angled so your legs don't hit the lock.

From the rider's perspective, you're putting the bracket on the seat tube angled at about 9-10 o'clock. In other words, from the rider's perspective looking down, it's angled off to the upper left. Mount it as low as possible that it still clears the bottle. Don't tighten fully yet - make it snug but with the ability to squirm to adjust the angle a little. Set the rotation of the bracket (the notched interface) back to 0°, straight up and down.

Then do the thing that is most often overlooked: using a 3mm allen wrench, adjust the angle of the metal slider on the lock shackle to match the angle you put the bracket on the seat tube, such that when inserted the lock is parallel with the frame centerline. It's going to overlay the seat tube and the back wheel/fender. You're trying to adjust the angle of the slider and the bracket until the lock is as close in as possible while still being able to come in and out of the bracket. You need it close in so your legs don't hit it. Leave it snug only until the adjustments are complete, then tighten down both the slider and the lock bracket.

In this position, it may be impossible to keep the lock from smacking the frame when you roll over a big bump. It's not a major concern, but if it's an annoyance you can pad the shackle with something to damp the sound.


I've almost found a reasonable setup by using the Transit Flexframe-U Bracket ability to rotate itself a bit like this:

enter image description here

enter image description here

This setup:

  • completely clears my legs
  • keeps both bottles accessible

Unfortunately, no matter how hard I tried, the setup is too noisy, perhaps because I was unable to properly tightly fix the Flexframe to my bike and rocks. I wonder if this is a fundamental design flaw, or incompatibility with my relatively wide top frame tube, but I still felt like this was worth documenting here.

The center of mass is not the best, but does the job.

This other question documents some other Kryptonite possibilities more globally: Alternate mount for Kryptonite U-Lock?

  • Noise in that mount likely comes from the lock itself jiggling in the holder. It's a design flaw, even if the mount feels welded to the frame, the lock will still rock and make your presence audible. Commented Jan 5 at 21:12

I recently had that bracket on the fork on my hybrid, where it worked well for about 8 years. Done sensibly, there's no risk whatsoever of it ending up in your spokes. Doing it up reasonable tight will ensure it can't swing by itself, and any impact that would knock it into the wheel would be hard enough to knock you off the bike anyway. I originally moved it to the fork to improve the weight distribution when using a baby seat. This was the back of the left fork leg.

Before that I used it on the seatstay, where it fitted inside my pannier rack.

I did also use it on the seat tube pointing backwards and slightly outwards, but it didn't work as well as my Masterlock bracket there. And that was with a lot more rear wheel clearance than you have.


I would be inclined to go low-tech, and just use some velcro ties. It's a bit hard to judge because the lock is at an angle, but it looks like if the lock were raised to sit just below the top tube it would clear the bottle and not need to be mounted at an angle.

I would use two ties on the top tube to support it and one (longer) tie on the head tube to keep it from swinging around too much. A piece of innertube clamped in place with zip ties would keep the lock from banging into the top tube, and the bottom being free would mean you push it out of the way to get at the bottle on the down tube.


Another option is to attach the mount to the seat tube with the lock positioned to the side of the bike, extending to the back. The majority of the lock will be along the rear triangle.

Another option is to mount the lock on a rear cargo rack. If you have a pannier, you can simply put the lock within it. If you don't, you can generally fit the lock into the holes in the side of the rack.

I would avoid using velcro and other difficult to manipulate fixtures to hold the lock to your frame. These certainly work, but can take minutes to get all snugged down properly so the lock isn't bouncing around during your ride. It would be fine for the first few times, but then, an a hurry to get going, you're going to end up not taking the time to properly snug it down and you'll have a lock bouncing around and (possibly) falling out.

  • 1
    Velcro also tends to erode the paint on a frame over time. Even the softer loop part abrades the finish.
    – Criggie
    Commented Jan 1 at 20:52
  • That's indeed the solution I had when using a U-Lock, but it doesn't seem straightforward with Kryptonite's design, as the mount is on the "u" itself and the mount is quite long.
    – Rеnаud
    Commented Jan 2 at 8:35

two bottles I also need to carry

You don't need to carry two bottles, and especially you don't need to carry them in a bottle holder if you choose to carry water with you. You may want to carry two bottles, but this is not a necessity.

Bike trips about 50 km and below in reasonable weather don't require dehydration during the trip. Just ensure that you are well-hydrated before the ride, and drink immediately after the ride.

If you make longer trips, you have several options:

  1. Buy something to drink at a grocery store. Yes, it costs a bit of money, but it's way cheaper than gasoline in a car would cost for the same distance. Since you carry a lock, this is a possibility for you.
  2. Put your water bottle elsewhere than in your frame. You can for example carry a messenger bag and put one bottle of water in there. You may also have a saddlebag big enough for a bottle.
  3. Carry them in your frame using bottle holders. This is not a necessity, you don't need to carry bottles in your frame since it's not too inconvenient to stop every 30-50 km, take a bottle of water from a saddlebag / messenger bag and drink it.

Having a gulp of water every 5 min is not a necessity. Your body has adequate water reserves, so a bigger amount of water every hour or two is enough.

  • 2
    Two bottles is a must for me. I consistently drink them up on 60k rides even without heat. And with heat, relying on stores can be dangerous in sparser countryside, I have specific experience of this. Different bottle storage locations can be considered however. Commented Dec 31, 2023 at 11:46
  • 4
    Nothing about this answer is good or generalizable across different fitness levels, locales, terrains, or climates.
    – Paul H
    Commented Dec 31, 2023 at 13:23

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