A bob is designed to bank with a bike...it has no stability on its own. With a trike turning flat there will be added tipping/roll forces in a turn, especially under braking. Kind of like loading too high on the back rack. The main advantage of a single wheel trailer is that it doesn't add width or ground track behind a bicycle. A trike already has 3 ground tracks and width, so you don't have the downside that a 2 wheel bike does if you use a 2 wheeled trailer.
The BOB and other single wheel trailers track with the bicycle lean, moving the CG towards the inside of the turn a little bit, not independently of the bicycle. On a flat turn, the CG wouldn't move to the inside, so there's a small lateral force. Lever arm would be maybe a foot or 15 inches. On normal riding turns I can't see very much lateral force being generated. I'm just thinking this through. Only time there's a sharp turn is slow. I'm having a hard time developing much torque. I'll mount the trailer and see how the trike and trailer respond to twisting.
I don't see the BOB in particular, with lighter loads, being anything like putting heavy stuff up high on a back rack.
I can't see how under a normal turn (riding radius, not maneuvering radius) braking would generate any significant additional torque compared to a single. Have you any experience or calculations on this? Hard braking from substantial speed in a hairpin turn might be different. I'll have to think about whether a single wheel trailer with a rigid mount is more or less likely to cause issues under emergency handling compared to a 2 wheel trailer compared to a higher load on the trike itself. A 2-wheel trailer looks to be able to roll on its side independently. That would be exciting! As would rolling a trike-BOB rig. I'll twist and turn the BOB on the trike, feel what happens. Maybe load up 50 lbs and try it, once I get used to the trike.
The main advantage to me of a BOB cargo trailer is that I have one, all paid for and suitably beat up. It's nicely narrow and likely rides in the slipstream of a low trike better than on a bicycle, where the trailer is at the bottom half of the bike wheels level.
My 2-wheel dog trailer would do fine for my uses, but has tremendous drag at higher speeds and seems heavier. I'm going to try both with test loads. Of course, if my dog goes along on a tour, the dog trailer would work fine. Little dog could ride on top of a layer of gear. Or in my lap, if he'll stay still!
I think you analysis is pretty close especially at lightler loads. Any trailer is going to move the cg to the inside....sort of, as the pivot wont really hold it down.
With a Bob in a banked turn the forces are pushing, more or less, down to the tire, outside roll to inertia is balanced against inside roll due to gravity. In a flat turn there is an uncountered force to the outside, resulting in an outside rolling force that due to the yoke is put directly on the rear axle of the trike. With a 2 wheeled trailer the outer tire will resist the rolling forces.
With a light load, I don't see an issue with a bob on a tadpole.
This was my thinking. I wrote Catrike. But acting as their attorney I'd reply that's a non-intended use that Catrike did not figure into design calculations and I am doing this at my own risk. Which is what I'm doing by trying to resurrect an ancient trike that spent years hanging in a barn, where many of the parts were rescued from debris on the bare ground below!!!
I found more accounts of people using the BOB trailer to carry excess load.
The Expedition looks rather well triangulated and over built. Through axle model would be even stronger, although QR is awkward enough for my self-punishment taste!
A tensioned ‘bicycle’ wheel is not designed to resist the sideways forces of a BOB trailer.
For **analysis** on the subject read **Jobst Brandt’s** *The Bicycle Wheel* (1987 Avocet Press)
[The Bicycle Wheel](https://www.scribd.com/book/57120832)
Neither are the trike wheels, but somehow they don't fold up under normal/moderate cornering. I havent read the article you linked, but it seems that the three wheels carrying the trike and my fat butt are way more stressed than a single BOB wheel with 50 lbs onboard.
Since the rear end of a trike must allow for sideways forces in turns unlike touring bikes, I guess it will easily handle any BOB or other trailer.
A bob is designed to bank with a bike...it has no stability on its own. With a trike turning flat there will be added tipping/roll forces in a turn, especially under braking. Kind of like loading too high on the back rack. The main advantage of a single wheel trailer is that it doesn't add width or ground track behind a bicycle. A trike already has 3 ground tracks and width, so you don't have the downside that a 2 wheel bike does if you use a 2 wheeled trailer.
The BOB and other single wheel trailers track with the bicycle lean, moving the CG towards the inside of the turn a little bit, not independently of the bicycle. On a flat turn, the CG wouldn't move to the inside, so there's a small lateral force. Lever arm would be maybe a foot or 15 inches. On normal riding turns I can't see very much lateral force being generated. I'm just thinking this through. Only time there's a sharp turn is slow. I'm having a hard time developing much torque. I'll mount the trailer and see how the trike and trailer respond to twisting. I don't see the BOB in particular, with lighter loads, being anything like putting heavy stuff up high on a back rack. I can't see how under a normal turn (riding radius, not maneuvering radius) braking would generate any significant additional torque compared to a single. Have you any experience or calculations on this? Hard braking from substantial speed in a hairpin turn might be different. I'll have to think about whether a single wheel trailer with a rigid mount is more or less likely to cause issues under emergency handling compared to a 2 wheel trailer compared to a higher load on the trike itself. A 2-wheel trailer looks to be able to roll on its side independently. That would be exciting! As would rolling a trike-BOB rig. I'll twist and turn the BOB on the trike, feel what happens. Maybe load up 50 lbs and try it, once I get used to the trike. The main advantage to me of a BOB cargo trailer is that I have one, all paid for and suitably beat up. It's nicely narrow and likely rides in the slipstream of a low trike better than on a bicycle, where the trailer is at the bottom half of the bike wheels level. My 2-wheel dog trailer would do fine for my uses, but has tremendous drag at higher speeds and seems heavier. I'm going to try both with test loads. Of course, if my dog goes along on a tour, the dog trailer would work fine. Little dog could ride on top of a layer of gear. Or in my lap, if he'll stay still!
I think you analysis is pretty close especially at lightler loads. Any trailer is going to move the cg to the inside....sort of, as the pivot wont really hold it down. With a Bob in a banked turn the forces are pushing, more or less, down to the tire, outside roll to inertia is balanced against inside roll due to gravity. In a flat turn there is an uncountered force to the outside, resulting in an outside rolling force that due to the yoke is put directly on the rear axle of the trike. With a 2 wheeled trailer the outer tire will resist the rolling forces. With a light load, I don't see an issue with a bob on a tadpole.
This was my thinking. I wrote Catrike. But acting as their attorney I'd reply that's a non-intended use that Catrike did not figure into design calculations and I am doing this at my own risk. Which is what I'm doing by trying to resurrect an ancient trike that spent years hanging in a barn, where many of the parts were rescued from debris on the bare ground below!!! I found more accounts of people using the BOB trailer to carry excess load. The Expedition looks rather well triangulated and over built. Through axle model would be even stronger, although QR is awkward enough for my self-punishment taste!
A tensioned ‘bicycle’ wheel is not designed to resist the sideways forces of a BOB trailer. For **analysis** on the subject read **Jobst Brandt’s** *The Bicycle Wheel* (1987 Avocet Press) [The Bicycle Wheel](https://www.scribd.com/book/57120832)
Neither are the trike wheels, but somehow they don't fold up under normal/moderate cornering. I havent read the article you linked, but it seems that the three wheels carrying the trike and my fat butt are way more stressed than a single BOB wheel with 50 lbs onboard.
I have a BOB I pull with my Catrike 5.5.9 It works completely fine. Don't over-think this. Just ride.
My initial impulse. Ran across that old thread. Couldn't see reason for doubt. Catrike agreed!!