Bumper mounted bike rack

[Campingwith2kids2dogs]

This is a heated discussion between DW & I. We have a Wildcat 312BH-OK. Since it's an Extralite, she says we can not mount our bike rack on the bumper because of discussions she has read here on the FR forums. She said that it causes the bumper to flex when driving which is why we kept loosing sewer end caps from the bumper of our last light weight 5er. I have hauled the bikes in the past & it seems sturdy enough.

[Rugged Brown]

Listen to the wife. Full stop!


Post the pics Herk!

[ependydad]

Yup. Wife's right - ultralight or not, bumpers weren't designed for carrying much of anything.

I have friends who had their bikes drag down the road days after being all proud of his new bike rack attachment for it.

Heck, I wasn't even game for the bike carrier offered as an option from Sabre because I'd read about the beatings that bikes take on the back of campers.

[OldCoot]

Listen to your wife! Better to listen to her now than after you deposit your bikes/bumper on the road somewhere and possibly cause a serious accident.

[garbonz]

Unless you have a factory bumper mounted rack that is already designed for the load, I wouldn't do it.

[nwslmn]

Now what about the spare tire? Two adult bike have to be lighter then that... right?

[ependydad]

Originally Posted by nwslmn

Now what about the spare tire? Two adult bike have to be lighter then that... right?

Not necessarily. Adult bikes can be HEAVY unless you pay for a lighter bike.

That said - when I had my pop-up, I carried 3 bikes using a Thule Raceway on the back of our Durango. To carry more, I would have gotten Thule products to carry them on top of the SUV. Just prepare yourself for sticker shock - $$$.

[rockfordroo]

I had a receiver welded to the frame and bumper by the RV dealer, certified welder had to do it. Roo 19. Haven't had any problems.

[Tailwind]

The main difference is not just weight, it is the twisting force, or torque. the bikes ride much farther out away from the bumper than the tire, thus greatly increasing the torque. Try this, push down hard on your bike rack just above where it us mounted. Then push down just as hard at the farthest end of the rack. I'd bet you can see your bumper twist. Now imagine this twisting happening a hundred times a minute as you cruise down the road --- get the picture? And yes, this does happen, always.

[bakken]

Originally Posted by rockfordroo

I had a receiver welded to the frame and bumper by the RV dealer, certified welder had to do it. Roo 19. Haven't had any problems.

Yet!
Was the welder also a structural engineer?

[OldCoot]

Originally Posted by bakken

Yet!
Was the welder also a structural engineer?

One does not have to be a structural engineer to fabricate and build a hitch or know what the frame will take. Experience is a wonderful teacher. Have seen plenty of "degreed engineers" that were great with the paper and dumber than a fence post with practical application. Just what I've observed over the years. Kansas City sky walk was a prime example.

Bottom line, it is foolish to add a bike rack to the rear of a "lite wt" camper bumper. You are asking for big trouble.

[rockfordroo]

I'm not saying you don't need to be careful.

But I've actually READ the report on the KC skywalk. Fault wasn't with the "degreed engineers" who designed it. They specified single (20 ft, as I recall) threaded rods to hang the skywalks. The CONTRACTOR (not a professional engineer, just "experienced," but apprently not experienced enough) decided to use two 10ft rods instead and jury-rigged a connection between them. (I don't recall if they were overbudget and thought two 10 footers was cheaper, or if they couldn't get the 20 footers when they needed them; it was one of those two reasons.) Anyway, it was the connection between the two rods that failed. The original 20 ft rods were plenty strong enough as designed by the engineers.

[Taylorgso]

Then try the Tacoma Narrows Bridge! I'm sure there was a design fault there!

[Jim Scofield]

I would go to a hitch shop and talk to a professional. I'm sure people here may be passionate but a hitch shop will easily come up with a safe solution for you.

[nwslmn]

Ok, you guys sold me. I'm leaving them in the rear bike door for which it was intended! Rockwood 8286ws

[OldCoot]

Originally Posted by rockfordroo

...The original 20 ft rods were plenty strong enough as designed by the engineers.

There were still engineers over looking the construction that should have caught it. Changes are not made without engr. approval.

Matters not with the discussion at hand. Sorry to have brought it up.

[rockfordroo]

Changes are not made without engr. approval.

Not necessarily true. In this case, the design engineers were NOT consulted. You can't trust a contractor any more than you can trust anyone else.

We're all trusting that our hitch designers are doing it right. But you never know. And you never know if the welder putting it together didn't get distracted and end up with a void in his weld, that cracks just as you go over that rough railroad track. Your also trusting that the bike rack is adequate. Same design and construction issues apply.

"You pays your money and you takes your chances!"

[rockfordroo]

Correction: Couldn't find the report, but here's what Wikipedia had to say:

Investigators concluded that the basic problem was a lack of proper communication between Jack D. Gillum and Associates [designers] and Havens Steel [contractor]. In particular, the drawings prepared by Jack D. Gillum and Associates were only preliminary sketches but were interpreted by Havens as finalized drawings. Jack D. Gillum and Associates failed to review the initial design thoroughly, and accepted Havens' proposed plan without performing basic calculations that would have revealed its serious intrinsic flaws — in particular, the doubling of the load on the fourth-floor beams.

You can see a pic of what the bad design looked like and how it failed. Bottom line: you're always the mercy of anyone who's been involved, engineer or "experienced" person.

[OldCoot]

Originally Posted by rockfordroo

Not necessarily true. In this case, the design engineers were NOT consulted...

Design engr's might not have been consulted but there had to be an "engineer" on site during the construction and I find it hard to believe a construction foreman made the decision without consulting the "on site engineer". The foreman may not be the sharpest tack in the pack, but they are not stupid. Did the design engineers not inspect the project when finished? tsk, tsk.

[Jim Scofield]

anybody can add anything to Wikipedia