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I recently was involved in a wreck, because I was unable to slow my trailer. I am thinking about building a refit kit to install brakes on a trailer, but I don't want to reinvent the wheel.

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  • What type of brakes are currently installed on the bike? My thought is this may be your best and simplest upgrade.
    – mikes
    Nov 16, 2013 at 3:06
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    The bike has great hydraulic disk brakes. When the trailer is going faster than the bike you crash. You want to slow the trailer and the bike. This is why trailer brakes are required on semis and other heavy trailers.
    – hildred
    Nov 16, 2013 at 3:31
  • I did see a bike trailer once that had brakes (of the type that were activated by force on the tongue). IIRC it was a heavily-built utility trailer, and may have been homemade. I would guess that there are utility-type trailers with brakes sold in Europe, but they approach cycling differently there vs the US. Nov 16, 2013 at 12:59
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    I don't see how the trailer can be going faster than the bike since every bike hitch I've seen is rigid, so when the bike slows, the trailer either has to slow, or pitch around and "jackknife". That said, CycleTote does sell an (expensive) automatic braking system for their trailers. Since it's an add-on accessory, perhaps you can adapt it for your bike and trailer.
    – Johnny
    Nov 19, 2013 at 18:07
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    @Johnny Fishtailing is where when because the trailer wants to go faster than the pulling vehicle it moves from side to side. as you slow the pulling vehicle, it becomes more severe. the three ways to stop fishtailing are accelerate, brake the trailer, or crash. I crashed.
    – hildred
    Nov 19, 2013 at 19:35

4 Answers 4

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According to Google Translate, http://www.weber-products.de/products/kargo/ offers an overrun brake as an option.

Beim Bremsvorgang erhöht sich das Gewicht des Anhängers um ein vielfaches. Deshalb empfiehlt sich für einen größeren Anhänger mit schwerer Ladung eine Auflaufbremse. Diese verstärkt beim Bremsvorgang die Bremswirkung und sorgt damit für viel mehr Sicherheit.

And having found that, an image search for "auflaufbremse fahrradanhänger" finds several more, but I don't know how many are commercially available.

http://viadukt.eu/produkt/PT6_Bike_Trailer-2-65-111.htm was the only commercial example I could find at the time of first answering. Dead link as of December 2015, still at http://web.archive.org/web/20150922174819/http://viadukt.eu/produkt/PT6_Bike_Trailer-2-65-111.htm

Excerpt from page:

Two disc brakes, which act as overrun brakes, ensure a high degree of safety when cycling and braking, even at full loading. The PT 6 is fitted with two large balloon tyres for extra cushioning.

PT6 trailer

DIY:

Pivot at tow-hitch Balancing pulleys Right-side/non-drawbar side brake

Right side brake Overrun pivot using a spring.  This is at the corner or elbow of the drawbar not at the hitch.

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  • Its disappointing that with all the vendors selling bike trailers that there is only one selling one with brakes, and nobody selling conversion kits.
    – hildred
    Nov 19, 2013 at 16:25
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    @hildred - One tricky part is the way the tongue is generally arranged. It's usually on one side, so it can attach near the rear wheel axle, and this makes it difficult to design a telescoping tongue (for inertia braking) that won't twist sideways when it telescopes. Nov 19, 2013 at 16:44
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    @hildred: I have made and used a lot of spring hitches. They oscillate a bit, sure, but they're also very robust. That matters when a rigid hitch is $100+ and breaks the first time the bike falls over. moz.geek.nz/mozbike/build/masstrailer/index.html for example.
    – Móż
    Nov 19, 2013 at 21:23
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    That last image looks scary - the failure mode appears to be "trailer runs into rear wheel of bike". Better than the other one, I suppose, where it's "trailer hitch into spokes".
    – Móż
    Dec 28, 2015 at 0:37
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    ...and what is up with the crinkle-cut spokes on the yellow-hulled trailer ?
    – Criggie
    Jun 28, 2021 at 8:20
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I'm not aware of a commerically made one, I suspect the barrier is liability issues (and possible legal issues in some places). FWIW, the limits in Australia and New Zealand are the same as for any other vehicle, so the main restriction is that the trailer can't weigh more than the towing vehicle (note below). Other jurisdictions may have different rules.

Similar questions have been asked here before: Hitch for a cart for braking How to make a cargo trailer?

There are two basic ways to do this. Either have brakes on the trailer activated by a lever on the bike, or make some kind of inertia brake. Having a direct lever is very simple and intuitive for the rider, but you may find yourself limited by the length of brake cables you can buy (it's possible to buy the wire on a roll and fix the endcap yourself, but annoying).

An inertia brake is somewhat harder to build, but very effective. You need the towing arm to telescope somehow, so as the trailer pushes forward on the towing vehicle you have a small movement that you can use to apply brakes. I built a four wheel trailer that worked like this, and just used cheap V brakes on the trailer. That was sufficiently effective that I didn't bother with anything more complex. The drawbar was square tubing, with a bracket at the overlap holding one end of the brake cables.

The major caveat is that neither of those solves the real problem. Once you're sliding along the ground in front of the moving trailer, neither of those will help slow it down. In theory you could grab the brake lever and use that, but in practice you're likely to focus more on getting out from under the trailer.

My preferred solution is to use a bike with two rear wheels, either a four wheel bike or a delta trike. That way you're less likely to fall off it and you can have the trailer apply downforce between the rear wheels to help with traction.

(edit: note that the default limit is actually the unloaded mass of the towing vehicle that the total trailer mass has to be under, so most bike trailers fall well outside that limit. Here's a PDF. What saves the situation is that if the manufacturer specifies a limit that applies instead).

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    I saw the discussion you mentioned for building the hitch, but I was really looking for what is being sold. Also could you clarify your point about weights, is that for trailers without brakes? I drove commercial here in the us and most of the semis pulled trailers which out massed them.
    – hildred
    Nov 17, 2013 at 18:43
  • @hildred: Like I said, I've never seen a commercial setup with a brake that could be used while riding. The only trailer brakes I've seen are on the prams that convert to kddie trailers, with brakes that can be operated from the pram end. Articulated vehicles are a special case, but I have not looked into getting a bicycle compliant with those. I have driven heavy vehicles too, but the legal issues are well outside the scope of bicycles.SE.
    – Móż
    Nov 17, 2013 at 20:38
  • Cutting a brake hose to length and fitting end caps is a 5 minute job, with a pair of wire cutters.
    – Vorac
    Nov 18, 2013 at 9:02
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    The tricky bit with a brake hose is going to be that you want to be able to split it, so you can take the trailer off.
    – armb
    Nov 19, 2013 at 11:06
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    @armb: I assumed you would take the brake lever off. That strikes me as easier than including a hydraulic coupling, and means the trailer can be used with any bike as long as the rider is willing to risk it.
    – Móż
    Nov 19, 2013 at 21:20
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What I do for my bicycle trailer is pretty simple:

I made a rider-controlled trailer brake lever as part of the trailer unit. This makes connecting and disconnecting the trailer from the bicycle easy, since the brake cable(s) do not have to be detached and re-attached.The bicyclist can activate the brake by pushing the paddle backwards with his buttocks.

An additional advantage of this system is that both the rider's hands are free to use the caliper brakes on the handlebars of the bicycle for additional stopping power, and the cyclist can control the relative degree of braking between the front bicycle wheel, rear bicycle wheel and trailer for the safest possible operation.

Furthermore, this design protocol is economical and easy to repair as needed. (I never needed to repair my system ever since I built it almost two years ago.)

I posted a YouTube video showing how effective my paddle brake lever, which is completely independent of the bicycle set up, works.I may be using a road bicycle in the video, but the problem is applicable to any bicycle type.The point is that using a brake on the trailer does help us ride our bicycles without worrying about the heavy trailer affecting any kind of slowing and stopping distance.The link is below:

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    I have downloaded your video and watched it at least half a dozen times, and although it has the advantage of working with a simple hitch disconnect, It scares me. I finally figured out why. When you are in a near crash situation, your instinct is to get low and hold on, where as your design requires you to loosen up rase and slide back, which is not only counterintuitive, it lessens control.
    – hildred
    Aug 19, 2015 at 17:50
  • I share some of @hildred's misgivings, but getting your weight back as well as low is good braking technique in may cases. Anyway if the use case was long descents this might be useful to avoid overuse of the bike's own brakes; then you'd be in position already for a sudden stop
    – Chris H
    Jun 28, 2021 at 8:37
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The Carla Cargo trailer (https://www.carlacargo.de/en/) has automatic overrun brakes. The trailer is attached to the seatpost and when it pushes the bike, the brakes get triggered automatically. It's also extremely stable because unlike all other bicycle trailers it has 3 wheels.

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