Bicycle trailers commonly connect to the bike in one of four hitch positions:

  1. A. Rear drop-out (single-sided, usually left/NDS drop-out)

    1B. Rear drop-out (both sides; often found in BOB trailers)

  2. Rear rack

  3. Seat stay

How is bike or trailer stability affected by the position of the hitch?

  • 1
    It would seem to me that the most stable position would be to have the hitch on the same plane as the bicycle hubs -- so the dropout position is best. But there are enough rack/seat-stay mount trailers to make me wonder if there are advantages to those. – RoboKaren Aug 16 '17 at 23:26
  • Having the hitch on the axis of the bike would also seem to have advantages in terms of symmetrical forces when pulling hard or when you hit the brakes. But in the horizontal plane there's another variable to consider. Taking mine as an example: it attaches to the skewer on the left. I was surprised to realise that it tracks left of centre - so the centre of mass doesn't directly sit behind the bike (and by more than the difference in hub widths; I don't have a particularly chunky frame either) – Chris H Aug 17 '17 at 5:54

In my experience, an axle mount is most stable compared to a seatpost mount.

With the seatpost clamp, the differences are most evident when braking and when turning. The contact point is a hefty "shove" from the side/rear, and because its so much higher than your wheels it has enough leverage to be noticed.

Imagine, turning at any speed and for some reason the trailer hangs up on a bump or pothole for an instant. Your saddle ends up being "pulled" to the inside of the turn.

Imagine when braking, your free-running trailer is shoving you up the seatpost and fighting the brakes. If you're hard-stopping so 90+% of the braking is on your front wheel, then the back wheel can be lifted clear off the ground and get pivoted sideways by the trailer.

When towing, rear wheel braking increases in importance from "almost useless" to "quite a good idea"

Note I've never tried a BOB-type connector where the pivot is behind the rear wheel. I imagine these feel like axle mount trailers.

A chainstay clamp might be convenient but mine almost fell off several times, so upgraded to a towball and hitch for safety.

  • is your towball hitch on the rear dropout? I'd love to see how you configured it. – RoboKaren Aug 17 '17 at 21:53

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