Towing trailers with a Brompton

[syklist]

Anyone have experience of towing trailers with a Brompton? I have been reluctant to try given that all the forces will be transmitted back to the frame via the hinge pin. I've always thought that the hinge pin was a bit under engineered and the trailer I will be using will weigh around 35kg and would be pulled up significant hills (Weber coupling attached above the wheel nut). I asked the Dutch importer many years ago and he was of the strong opinion that this would not be a problem.

[[XAP]Bob]

Which pin are you concerned about? I don't see any issue. There was an article in cycle a while ago about someone who toured the Scottish isle towing a kayak, and putting the Brompton in the kayak for crossings...

[syklist]

Which pin are you concerned about? I don't see any issue. There was an article in cycle a while ago about someone who toured the Scottish isle towing a kayak, and putting the Brompton in the kayak for crossings...

The rear fork hinge pin just by the bottom bracket.

[rfryer]

I can't see that the forces from the trailer go anywhere near the hinge pin, except under heavy front-wheel braking. The forward force on the bike is transmitted from the wheel via the rear drop-outs, which are right next to where the trailer is connected. And under heavy braking with a heavy trailer, I'd contend that a bit of extra strain on the hinge pin is the least of your problems!

The only way that the hinge-pin might be affected is if you expect to pedal much harder in order to maintain the same speed that you'd have have been doing without the trailer. But I expect that you're more likely to pedal no harder than before, and just go a bit slower!

[resus1uk]

I use a Carry Freedom trailer with the polymer lollipop connection. The bracket is left attached to the Brompton & doesn't affect the fold. The trailer is shared with a Dutch Gazelle bike & a Bob Jackson.
No problem towing, the polymer connection seems to cushion the forces.

[syklist]

I can't see that the forces from the trailer go anywhere near the hinge pin, except under heavy front-wheel braking. The forward force on the bike is transmitted from the wheel via the rear drop-outs, which are right next to where the trailer is connected. And under heavy braking with a heavy trailer, I'd contend that a bit of extra strain on the hinge pin is the least of your problems!

The only way that the hinge-pin might be affected is if you expect to pedal much harder in order to maintain the same speed that you'd have have been doing without the trailer. But I expect that you're more likely to pedal no harder than before, and just go a bit slower!

The trailer will push and pull on the rear wheel nut/triangle applying forces through it via the trailer hitch. These forces are then transmitted to the frame which is the heavy part of the bike as it is where the rider sits. Most of these forces will be transferred via the rear hinge pin with a small proportion of the horizontal forces transmitted to the elastomer spring. In a similar way that the trailer transmits forces to the rear triangle. I can't see how towing a trailer will not increase the loading on the hinge pin. Especially with a trailer like the Dolphin which sits offset to the left relative to the bike and will have a slightly greater turning force in the horizontal plane.

[SA_SA_SA]

Perhaps you could ask Brompton:

AtoB magazine tend to recommend axle hitches for Bromptons, it seems quite common, and Brompton have not seemed to comment on it which would suggest a lack of a history of problems. The are however unhappy about heavy cantilevered loads (eg a heavily loaded QR seatpost rack) on the seatpost...

[Phil_Chadwick]

That pivot bearing has a pretty big load on it anyway. I suspect you would be loading it further, but probably not much outside the normal range of welly it gets from different weight riders riding the bike in different styles.

I tend to tear through pivot bearings on mine because I'm not especially light, and i do a lot of hard climbing on a SS Brommie

[Cunobelin]

I use both a Carry Freedom and a Radical Design Cyclone with the Brompton

Never had an issue

[Geoff.D]

I've just read the latest edition of Velovision, in which there is a piece about a new Radical trailer (The Chubby). It was tested by the editor when attached to a Brompton. There was also a short piece from a chap who had toured extensively with it, loaded with camping gear, behind his Brompton.

The subject was the trailer ( slightly larger, payload 45Kg, doubling as a flight bag) and there was no analysis of the stresses on the Brompton. However, both reported excellent handling characteristics, which I suspect indicates that the Brompton was well up to the job. Neither seemed to have any worry about towing with a Brompton.

[resus1uk]

Twice the price of my large Carry Freedom trailer but looks good and has wheels the same size as the Brompton.

[syklist]

I've just read the latest edition of Velovision, in which there is a piece about a new Radical trailer (The Chubby). It was tested by the editor when attached to a Brompton. There was also a short piece from a chap who had toured extensively with it, loaded with camping gear, behind his Brompton.

The subject was the trailer ( slightly larger, payload 45Kg, doubling as a flight bag) and there was no analysis of the stresses on the Brompton. However, both reported excellent handling characteristics, which I suspect indicates that the Brompton was well up to the job. Neither seemed to have any worry about towing with a Brompton.

OK good to know, I guess the pin is strong enough to take the extra strain. The maximum weight next summer will probably be something round 50kg + maybe towing a childs bike behind the trailer. So another 10kg? Our main trailer the Dolphin sits offset on the hitch which means that the forces will be skewed slightly. We haven't noticed any problem with this on our big tourers but it might have an effect on our Bromptons as they carry 20kg over the front wheels. You never know until you try it.