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There are a couple of pretty good answers in How to make a cargo trailer?. After looking at those, at the answer to What are the safety concerns of a high vs a low mount trailer hitch? and doing some other research, it seems that heavy trailers have significant safety issues around braking.

All the references I found so far indicate solutions that involve disconnecting the bike's rear brake and connecting the cable to trailer brakes. This solution has issues of its own (mainly around not going to the trouble).

There is common solution often used on rental automotive trailers, called a surge brake.

Surge Brake image

When the tow vehicle slows down, the trailer pushes against the vehicle and that force applies the trailer brakes. In automotive solutions this is done with hydraulics.

After thinking about this a while, and noticing there are many inexpensive used kids bikes with manually applied brakes integrated in the rear wheel.

Are there any proven approaches to using surge braking on bike trailers, either with used bike parts or with new purpose constructed parts?

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    Clearly one could build a surge brake for a bike trailer. Probably a cable system would be most practical. But given the usual light weight of a bike trailer you would need substantial "travel" (probably 2-4 inches) to apply enough brake force, meaning you need a lever or pulleys to convert the motion to the shorter, more forceful motion needed to drive standard rim brakes.
    – Daniel R Hicks
    Nov 21, 2014 at 12:47
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    On the other hand emergency-stopping a 150lb trailer without a brake on it could be interesting. You can assume you're not going in a perfectly straight line, so it will try to overtake you - hopefully on the hitch side and therefore without the towing arm hitting the back wheel. So it might be nice to have in a rare set of circumstances. Which makes it hard to test. Given the recent discussion about brake lights I wonder about an electrically-operated trailer brake. A few C-cells and a solenoid wouldn't add much weight. The switch would need to work in the same movement as normal braking.
    – Chris H
    Nov 21, 2014 at 14:05
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    This idea just popped in my mind: If you have cable brakes, there are brake lever that can actuate two cables at once. With one of those, you can leave one cable for the on-bike brake (I suggest rear one) and the other can be routed to a connector that allows to engage/disengage a cable brake sistem on the trailer.
    – Jahaziel
    Nov 21, 2014 at 15:07
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    I don't think you are going to find any surge brakes designed for trailer that light. Surge brakes slide metal surface to metal surface and it takes a lot of force. On my boat if I stop with surge engaged even two of us cannot push back on the boat hard enough to disengage - have to block the wheel and pull the truck forward. For that much weight and bulk I think you would be better off riding a trike as then you have two (three) wheels for braking and trailer cannot push you over.
    – paparazzo
    Nov 21, 2014 at 15:52
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    As someone who has spent a fair amount of time towing a 80 pound trailer over the last two years (chariot + 2 kids), I probably wouldn't recommend a surge brake. The ball in my trailer setup hops ALL over the place going up and down hills and the like. My gut feeling is that getting a switch that only engages when you want it to would be a tinkery process and probably waste far more time than just running a cable or hose all the way back there to get a brake you could actually control. Many bike polo players run various setups to allow dual braking with one hand. I'd investigate that.
    – Deleted User
    Nov 21, 2014 at 17:44

7 Answers 7

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The simple answer to your question is yes, people have built surge brakes and they do work. Specifically, I have built one, but I called it an inertia brake.

This page has some notes and photos. The mechanism was fairly simple and robust, a telescoping towing arm with a couple of standard brake cables leading to V brakes on the front wheels of the trailer.

enter image description here enter image description here

The major caveat in my opinion is that by the time the trailer is heavy enough to need these brakes it's too heavy to be towed safely behind a two wheeled bicycle. I say 'two wheeled' because in many countries legally speaking a bicycle has "two or more wheels" - so to a lawyer my quad bike is a bicycle. I built that trailer for the quad and would not suggest towing it behind a two wheeler. Mostly because if you fall off the bicycle the trailer brakes will not be applied so the trailer will roll straight over the top of you.

You may also find "does anyone sell bicycle trailers with brakes?" useful

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  • How how heavy do you figure your trailer has to be before you notice the brakes kicking in? Does your telescoping tongue ever stick?
    – ShemSeger
    Nov 22, 2014 at 21:28
  • It's around 200kg I suspect, but I rarely load it up unless the quad is also loaded so it's hard to tell - even 50kg in the quad means 45kg quad + 50kg load + 85kg me = going on 200kg. I notice even small rises, put it that way :)
    – Móż
    Nov 23, 2014 at 9:12
  • I like this solution, but as @DanielRHicks mentions in his comment to my question. Some kind of mechanical advantage in applying the brake pressure might be helpful, as well as a break away or dead man switch.
    – James Jenkins
    Nov 23, 2014 at 11:12
  • @JamesJenkins it's just balancing mechanical complexity and fabrication time against which features you really need. If you must have adjustable mechanical advantage you're going to have a more complex mechanism, and pay for that in maintenance and build time.
    – Móż
    Nov 23, 2014 at 20:51
  • Did you have problems adjusting both brakes on trailer to brake evenly? I guess for someone trying to sell such trailers that might be important issue (customer not having adjusted brakes correctly and suffering accident)
    – Davorin Ruševljan
    Nov 24, 2014 at 14:51
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I don't think surge braking is as user-friendly as a manuel braking system. Here is what I basically do for my 90-something trailer, on just one wheel...this should be even better if braking both of trailer's wheels:

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 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 didn't have to repair mine ever since I built it 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, one of the problems some of us may experience with surge brakes. The link is below:

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  • Great design, great video! How did the brake calipers actually attach on the trailer side? Do both sides have brake calipers or just one side? Do you feel it pull to one side if it's just one side? Again, great video!
    – RoboKaren
    Sep 25, 2015 at 2:05
  • butt brake, i love it.
    – ShemSeger
    Jun 27, 2020 at 2:51
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I don't think this has ever been done before for a lightweight bike trailer, which would mean no, there aren't any proven approaches to using surge brakes on a bicycle trailer, but I've got some ideas...

It would be very impractical to use any current trailer surge brake options on a bicycle trailer, they'd be too clunky, heavy and wouldn't be compatible with bike hitches. An alternate solution for braking would probably be more practical (extra lever on the handlebars), and less likely to fail, but I'll address your question as you've asked it; which means we're talking about engineering something completely new. Things you have to consider:

  1. Trailer - I think it's important to start with the trailer you plan on using, then think about how to modify it. I recommend something with a hitch like the Woody Wagon Canoe Bicycle Trailer:

enter image description here

  1. Brakes - Obviously you're going to have to go with hydraulic disc brakes, because cable brakes would have way too much stretch in them. The first thing you have to figure out is how to mount your brakes on the tralier. The ideal solution would be to buy some Chariot disk hubs like they use on their CX-1 trailer. You'll also need a hose splitter to operate both callipers with one lever.

  2. Actuation - This is going to be your biggest hurdle, and really what your question is all about. You could easily mount a stock brake lever to your hitch (likely with a customized lever), you just need to come up with a method of operating it with a custom made surge brake actuator.

Here's my concept for what I think would work best:

This is obviously a very simple illustration - use parallel hinges to 'hang' the trailer hitch from a receiver mounted to your seat post. Put the brake lever on the receiver, and let pendulum action from the momentum of the trailer actuate the brake lever.

enter image description here

You'll of course have to take wheel and cable clearance into consideration, and you'll have to calculate what hinge length will give you effective actuation, and actually connect the pendulum part to the lever in some way–and other fine details, etc... But theoretically, I think this would be the easiest, simplest, and most effective method of putting surge brakes on a bike trailer.

Updated Design:

Some good comments gave me some ideas for already improving on my concept. I moved the brake to the trailer side of the parallel hinges–which offers more tire clearance and keeps it out of the mud coming off the tire–and I simplified it by actually making one of the hinges double as the brake lever.

enter image description here

Another consideration is to be sure the wheels are secured to the canoe well enough that they don't get pulled out from underneath when the brake engages and rip your hydraulic hose out of the callipers/lever. Either a long bar to connect the hitch to wheels, or a long strap to prevent the wheels from sliding back could be necessary if the trailer wheels can't be adequately secured to the bottom of the canoe.

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    Wouldn't it be easier if the lever is on the trailer side? The force excerted on the lever would be the same but cable/hose routing would be a little bit easier.
    – Jahaziel
    Nov 21, 2014 at 20:44
  • +1 I think is a cool idea but I fear you would get a feedback loop. It would brake then as soon as the brake came on the trailer would pull back and come off the brakes. Even some bumps could actuate.
    – paparazzo
    Nov 21, 2014 at 21:01
  • @Jahaziel - Good idea, it would work both ways I think, but putting the lever on the top of the trailer side would certainly eliminate the tire clearance issue, and you're lever wouldn't gunked up by whatever the wheel is picking up.
    – ShemSeger
    Nov 21, 2014 at 21:10
  • @Blam - Ya probably, if you tried stopping too fast, but that happens with a lot of trailer brakes in my experience. I imagine with the right hinge length and slow braking that you could manage to come to smooth stop.
    – ShemSeger
    Nov 21, 2014 at 21:17
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    @Jahaziel - I took your suggestion and made a new concept. See my edited answer.
    – ShemSeger
    Nov 21, 2014 at 21:59
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In a comments you add that the bike and trailer / dolly must fit in canoe.

Dolly implies to me that you plan to use the canoe as the frame.
With a dolly / surge brake design I see a few problems:

  • Now you have a bit of hardware to attach the surge hitch to the canoe. In addition to the surge and brakes.
  • A dolly design must exert braking force so it has to be a significant dolly and firmly attached to the canoe
  • In order to act as the trailer it is bottom down and will collect rain
  • Even if you get the surge brake working you are going to take the hit on the bicycle before it kicks in so it is still going to push you over and then when it kicks in it will pull you over.

Consider a trike where you take everything but the canoe on the trike and now trailer the canoe upside down with a light weight dolly. No brakes, hitch is a simple pin, and a lighter weight dolly. And it would take less equipment to attach a dolly on the gunnel side. When you brake a trike the canoe would not push you over.

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  • +1 This is a good answer, I figured out how to carry a bike in canoe but how am I going to carry a trike in a canoe?
    – James Jenkins
    Nov 21, 2014 at 17:07
  • PS, there are several used Adult Trikes available in my area, in the $200 range, so this is a financially viable solution.
    – James Jenkins
    Nov 21, 2014 at 17:09
  • If you design the trike to fit then it fits. In net you need to carry everything and I see everything potentially being less with a trike. I just said consider.
    – paparazzo
    Nov 21, 2014 at 17:10
  • Specifically, you could build a recumbent trike into/around the canoe and that way you'd be sitting in the canoe pedalling on the road. With a bit of effort you could probably put all the complexity into a single steered, driven front wheel and the back wheels would just bolt on. That would probably simplify the design and build.
    – Móż
    Feb 9, 2016 at 23:53
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I have been looking at the problem for awhile. I use the conventional tow bar found on many small trailers. Firstly I use the chassis of one of these for my "caravan" set up 1800x860. Weight is around 70Kg gross. So the answer I'm working on is for a brake system to slow the trailer on hills and when parking. Using conventional brakes and a direct link to two solenoids (one on each brake) controlled bye a remote switch from a door bell which activates a low voltage solenoid that allows the 12 volt units to work giving 25N on each brake. Of course with the solar on the caravan I do have access to 12 volts, otherwise a small 12 volt battery would be needed. A work in progress I admit but that's life and it keeps the mind active.

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  • Nice first answer - welcome to the site!
    – Criggie ♦
    Dec 8, 2022 at 9:19
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Use disc brakes on the trailer's wheels, and mount a small battery on the trailer's frame.

Run the brake inner cable to a 60N pull-type solenoid mounted on trailer's frame, then put a small switch on the bike's handlebars to activate the solenoid.

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    Welcome to the site! Interesting idea, do you mind giving an example of such a solenoid sold somewhere? Not everyone here can calculate its parameters necessary to perform its functions adequately.
    – Grigory Rechistov
    Feb 16, 2019 at 8:07
  • This is an interesting idea - needs a lot of planning though. Perhaps start by disk braking the trailer and using a super-long inner/outer cable right up to the handlebars, and then consider electrifying that if the idea proves sound.
    – Criggie ♦
    Feb 16, 2019 at 23:38
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the guys from Carla cargo have released their solution as well (in German):

http://werkstatt-lastenrad.de/index.php?title=Bauanleitung_Carla_Cargo_Crowd#Nabenaufnahme_an_Gabel

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    Welcome to Bicycles @carla. We recommend that new members take the tour to make best use of the site. I'm flagging this as spam; please see the help center.
    – andy256
    Dec 3, 2016 at 19:37
  • You have a point, but SE best-practice is to summarise the article in your answer.
    – Criggie ♦
    Dec 3, 2016 at 22:31
  • Welcome to Bicycles SE. We prefer answers on this site to be self-contained. That way, the answer is still valid if the link dies. Please summarize what information is contained in the link within the body of your answer. Otherwise, it is likely to be downvoted, flagged for moderator intervention, and possibly deleted.
    – jimchristie ♦
    Dec 9, 2016 at 17:45

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