Bike rack for A/S bumper?

[dayner]

HiLoAgRV has a valid point. If the braking force provided by the trailer is low and the trailer is pushing the TV, and if the trailer COG is above the hitch C/L, the trailer will transfer a downward force to the TV. Conversely, if the trailer braking force is sufficient to pull backward on the TV and the COG is above the hitch C/L the trailer will provide a lifting force on the TV. The actual angle with respect to level between the trailer and TV is immaterial as the ball itself cannot transfer a moment It's a simple matter of moments. Complicating the solution a little is how weight is actually transferred thru a WD hitch as the WD hitch can transfer a moment, but a WD hitch does not change which direction the force produced works on the TV. If the trailer COG is below the hitch C/L, the entire force transfer discussion is reversed.

[Wayne&Sam]

Originally Posted by alozier

I just bought a 30 international from CanAm in London Ontario and they put a rear bumper bike rack on mine when I asked for a rack... I certainly don't want to damage my frame, I will have to ask them about it...

See picture below.



Attachment 139721

I just returned from Jackson Center where I saw alozier's rack and the prototype for Airstream's new rack. They are fairly similar.

The AS rack is heavier duty and adjustable to fit many different trailers, but very similar in design.

[pattonsr]

Wayne&Sam,

How does one access the rear outside compartment? Does the AS rack fold down?

Barry

[mefly2]

Originally Posted by Friday

I'm not disagreeing with the theory... but without some baseline statistics it's hard to link the cause and the effect. Your suggestion is 'improperly inflated airbags' are the cause. But, you haven't provided a baseline of accidents per mile (or however you want to measure it) for non-airbag equipped vehicles, 'properly' inflated air bags, and 'improperly' inflated bags.

You might see the stats and say "Well, there are a lot of big trailer wrecks, and the airbags were found to be too stiff". I investigate accidents... and before I came to that conclusion, I would want to back up and say "Of similar big trailer setups, what is the accident rate?" Because, it might be that once you reach a certain size bumper-pull, air bags are used at a high rate... so a high percentage of big trailers are going to be pulled by an air bag equipped vehicle. The next step would be to consider if the accident was caused by the air bags, or if a certain unavoidable action was complicated by air bags, or if the crash was going to happen regardless of the setup (not a loss of control situation).

Trailers don't wreck often, but of the few I've investigated, they have all been the result of the rear-end becoming unloaded... with the trailer pushing the back end out and the tow vehicle being jack-knifed... the result is usually a pile up in the ditch with one or both units on their side. From what I see of trailers, I'm amazed there aren't more wrecks...

Anyway... a typical scenario I've seen... vehicle is on a slight down grade, TV is coasting... TV enters corner... TV can't control speed OR radius of corner decreases (same effect)... TV initiates braking... trailer already has gained mass/momentum over the TV... trailer brakes are not able to give balance of control back to TV... back end of TV steps out... brakes are hammered (on TV)... full control of momentum is given to the trailer... rear traction on TV is zero... rig ends up in the ditch.

Often, the hitch is higher than the trailer ball, so any braking lead by the TV creates a lever unloading the back end... any type of braking creates a loss of control, and the greater the angle between the TV and trailer the more likely a wreck.

I haven't investigated an accident that was a loss of control initiated by swaying/oscillation - though I am sure they happen as well. In my area, we have 100's of miles of rolling, sweeping hills and corners (mountains) - so bad tow setups likely reveal themselves sooner in other ways before a sway issue can develop.

I am interested in how the new Ford anti-sway setup is working for people - as I see the real problem as managing the mass of the trailer - especially when it greatly exceeds the TV. A system like Ford that is linked into the stability control would be able to detect traction loss at any wheel, and link to the trailer brakes to manage the whole system as one unit... a very smart idea.

I am also interested in how newer suspension setups have affected sway issues... Older leaf-spring set ups had a huge amount of lateral flex... new setups have much more rigid frames and suspensions... Have accident rates gone up or down with the ever increasing capacity of TV's and the larger and larger trailers? I don't know - my sample size is much too small for me to make a guess...

Excellent analysis; thanks for taking the time to put your thoughts into words.

[JFScheck]

Just announced - Airstream is now selling a bike rack for International's & Safari's ( no Classic's) that mount on the Airstreams rear body & bumper!

Check it out on their web site!

[silverbacksurfer]

Just saw airstreams new bike rack on there site .https://store.airstream.com/product_...roducts_id=623 How is this different than a 2" receiver welded between the frame.

[dkottum]

Originally Posted by silverbacksurfer

Just saw airstreams new bike rack on there site .https://store.airstream.com/product_...roducts_id=623 How is this different than a 2" receiver welded between the frame.

I would think the receiver assembly and receiver, plus the bike rack that fits it, would far outweigh this Airstream rack that needs no receiver assembly.

The Fiamma rack is not only lighter than most receiver-type racks, it also allows the bike's wheels to rest on and strap to a rail under them. The Fiamma rack is mounted at the top securely to the trailer. The bikes are then strapped to arms on the rack.

I used a similar Fiamma rack on our VW camper traveling all over the country. They're a good setup. The bikes are rock-solid, not flopping around like on other bike racks I have had.

Airstream specifies a weight limit for the bikes, so (perhaps) they have an idea how much weight at a certain distance back from the axles the frame can hold. If you could match this total weight and distance back, the steadiness of the Airstream rack, and put it on the range of trailer models specified then I'm guessing the welded receiver would work.

For us under warranty, or those who may be able to strike a deal on water leaks or structural damage at the rear of the trailer after the warranty, it would be wise to use the factory rack.

doug k

[worldinchaos]

Originally Posted by silverbacksurfer

Just saw airstreams new bike rack on there site .https://store.airstream.com/product_...roducts_id=623 How is this different than a 2" receiver welded between the frame.

It appears that it is attached to the rear shell, from what I understand. This distributes the load better. I was just wondering, couldn't you also weld a receiver to the end of a 2" square box channel, long enough to reach crossmember nearest the centerline of the axles, and then u- bolt or weld it to the rear bumper frame, such that the load on the receiver would be distributed upwards into the frame in the middle as well as downwards on the very end?

[dkottum]

You could weld a lever that reached back towards the frame center, but if it is attached anywhere behind that for stability, the entire weight (aft of the attachment point) will be felt at that rearward attachment point. So nothing to gain.

If not supported rearward, it is simply a long lever putting great stresses on the weld and frame where it is attached (no damage to the rear though).

doug k

[Inland RV Center, In]

A coupler welded to the bottom of the frame in the rear of the trailer, will severely lower the ground clearance.

Next, in doing so, it adds weight to the frame, again not a good idea.

However, since the strenght is in the shell, attaching a bike carrier to the shell, avoids a ground clearance issue, as well as not adding but a very little weight to the frame.

The shell is the 'boss", not the frame.

Andy

[teagues]

Originally Posted by Inland RV Center, In

However, since the strenght is in the shell, attaching a bike carrier to the shell, avoids a ground clearance issue, as well as not adding but a very little weight to the frame.

The shell is the 'boss", not the frame.

Andy

Andy,
Do you like the design of the Fiamma bike rack?

[rock60]

i used a bike rack on the rear bumper for years, three bikes for three grandsons. 10 hr trips to the outer banks.

[Road Geezer]

When we were taking delivery of our AS, I asked the dealer about mounting a bike rack on the rear aluminum bumper. He said don't do it; the bumper itself is not strong enough to handle the torque. Instead, he said mount--weld or bolt-- the receiver hitch cross bar to the two steel chassis extensions that are just below the bumper.

You might look into this approach.

[Inland RV Center, In]

Originally Posted by Road Geezer

When we were taking delivery of our AS, I asked the dealer about mounting a bike rack on the rear aluminum bumper. He said don't do it; the bumper itself is not strong enough to handle the torque. Instead, he said mount--weld or bolt-- the receiver hitch cross bar to the two steel chassis extensions that are just below the bumper.

You might look into this approach.

The steel chassis extensions are the same thing as the bumper as far as the construction is concerned.

The shell is where the strength is, NOT the frame.

That dealer needs to learn more about Airstream's construction, and quit the guess work. It's monocoque, which means "load bearing shell."

The shell supports the frame and the bumper as well.

Sorry.

The new style bike rack, also attaches to the shell, which is a giant step in the right direction.

Andy

[Inland RV Center, In]

Originally Posted by teagues

Andy,
Do you like the design of the Fiamma bike rack?

Absolutely.

Andy

[teagues]

Originally Posted by Inland RV Center, In

Absolutely.

Andy

Thanks, Andy. I appreciate your input. Great to hear that there's finally a well designed bike rack solution available. Now if I can find somebody around here to install one.

[Garfield]

Originally Posted by JFScheck

Just announced - Airstream is now selling a bike rack for International's & Safari's ( no Classic's) that mount on the Airstreams rear body & bumper!

Check it out on their web site!

I hope Airstream paid Andy Thomson a decent royalty....I've been using his design since we got our Safari 4 years ago ... everything is rock solid and it works great!

[rp709]

Please check out the Airstream website: They now offer a bike rack that mount at the rear on the frame and body. What happened to the major no-no? Mounting a hitch receiver between the frame members and then using a bike rack works fine for many Airstreamers. The reason for Airstream's position is they don't want a hitch receiver installed because someone might tow another trailer behind the Airstream. That would stress out the frame. The new option avoids that potential liability but is clumsy and in the way. But bicycle weight in that location is not a problem.

[mikeandnora]

One heck of an ending to this ongoing debate by airstream huh?

[rp709]

Your bike rack idea should work fine. That is what I have done as have other friends. Can you imagine a vehicle with a gross weight rating of 7,000 plus having a frame that can't handle 50 lbs. on the back? An Airstream trailer has 90% of its weight below the floor. The frame is very strong. The shell provides stiffening to the structure, but not significant load bearing. Airstream's position is no doubt written by lawyers, worried about damage caused by towing another trailer behind. This leads some to assume engineers had a say in this position. Have fun! Ron