Forum Discussion

FLHTCI's avatar
FLHTCI
Explorer
Dec 10, 2016

Bumper strength

Hello, We have a 2013 Jaco Whitehawk. We'd like to install a receiver and a bike rack. I understand some RV bumpers are not strong enough to hold a bike rack. Any help would be appreciated. The bumper is a 4" square hollow metal bumper.
  • 1L243's avatar
    1L243
    Explorer II
    Jan 20, 2017
    westend wrote:
    The meat of the rear racks situation is that mounting any significant weight to a bumper is beyond the design of the load carrying ability of typical trailer bumpers and secondly, any weight put onto the extreme rear of the trailer frame is changing the load carrying design of the trailer.

    Some folks may have a situation where the tongue weight is greater than the design applications and adding weight on the rear may not be as consequential, as long as the frame has the ability to carry that weight without significant frame bending moments. The change in load moments is a difficult equation to discern because changes in the trailer attitude and road surface are brought into play. IOW, a frame that is at rest may be able to sustain the weight of rear load stationary moments but suffer failure from the extreme loads while on the road.

    It's a pickle and should be avoided unless an owner likes pickles.:)


    Agree...Every application has it's limits. I would not consider putting a heavy generator on a back bumper reinforced or not..

    Wow!
  • Atlee's avatar
    Atlee
    Explorer II
    Jan 20, 2017
    The bumper on my Koala has a sticker warning on it from the factory. It says to NOT mount anything to the bumper except the the factory supplied spare tire carrier.
  • jrichard's avatar
    jrichard
    Explorer
    Jan 19, 2017
    Following up on the previous comment:

    I bought a used TT with a Honda 3000 mounted on the rear bumper. With enclosure, I'm guessing around 160lbs. When I noticed the bumper rotating, I had a welding shop reinforce it similar to what has been suggested in other comments to provide support as well as stop the bumper from rotating.

    At the same time, I had a 2" receiver fabricated and attached to the frame so I could carry bikes on the back. Three bikes (two of which were kids) plus the bike rack was maybe 100lbs. I have no idea re: the weight of the receiver and reinforcement, but by that time I'm guessing I was up to +/- 400lbs.

    I didn't give it much thought. Until the frame bent just behind the rear axle. In fairness, it was a an ultralight trailer. It never towed poorly or gave any sign that disaster was imminent. At the end of the day, it was totaled.

    In any event, especially if you have an ultralight, I'd be slow to reinforce things to carry more weight--that weight gets transferred and will show up at the next weak spot.
  • westend's avatar
    westend
    Explorer
    Jan 01, 2017
    The meat of the rear racks situation is that mounting any significant weight to a bumper is beyond the design of the load carrying ability of typical trailer bumpers and secondly, any weight put onto the extreme rear of the trailer frame is changing the load carrying design of the trailer.

    Some folks may have a situation where the tongue weight is greater than the design applications and adding weight on the rear may not be as consequential, as long as the frame has the ability to carry that weight without significant frame bending moments. The change in load moments is a difficult equation to discern because changes in the trailer attitude and road surface are brought into play. IOW, a frame that is at rest may be able to sustain the weight of rear load stationary moments but suffer failure from the extreme loads while on the road.

    It's a pickle and should be avoided unless an owner likes pickles.:)
  • SoundGuy's avatar
    SoundGuy
    Explorer
    Jan 01, 2017
    ssthrd wrote:
    I never really gave it a thought before, but what about a spare tire? The last two travel trailers which we purchased new had the spare tire mounted on the rear "bumper". To this point after 20,000 miles, I see no Ill effects on the structure. I assume that the manufacturer mounted them there, but I don't know for sure.


    Well for what it's worth I haven't carried the spare tire on the rear bumper of any trailer we've owned. With our TrailCruiser hybrid I carried it in the truck, our KZ Spree I stored it in the front pass through cargo compartment, and with our current Coachmen Freedom Express which came with the spare hanging below the A frame with a winch to lower it to the ground I removed the winch entirely and also store the spare in the front pass through compartment. It takes up little room at all, is completely out of the weather, out of sight / out of mind yet readily available anytime I may need it, keeps the weight where it belongs in front of the axles, and the well formed by the wheel is a perfect spot for storing hoses and electrical cables.



    However, something anyone can safely hang off the rear bumper is this really handy clothes hanger.



    I was thinking about mounting a hitch to carry a 200 lb scooter behind the TT, but the good folks here talked me out of it.


    Smart decision. :)
  • Huntindog's avatar
    Huntindog
    Explorer
    Jan 01, 2017
    ssthrd wrote:
    I never really gave it a thought before, but what about a spare tire? The last two travel trailers which we purchased new had the spare tire mounted on the rear "bumper". To this point after 20,000 miles, I see no Ill effects on the structure. I assume that the manufacturer mounted them there, but I don't know for sure.

    I was thinking about mounting a hitch to carry a 200 lb scooter behind the TT, but the good folks here talked me out of it.
    My last TT the tire fell off the bumper. It took a few years and many thousands of miles, but it did fall off.
  • ssthrd's avatar
    ssthrd
    Explorer
    Jan 01, 2017
    I never really gave it a thought before, but what about a spare tire? The last two travel trailers which we purchased new had the spare tire mounted on the rear "bumper". To this point after 20,000 miles, I see no Ill effects on the structure. I assume that the manufacturer mounted them there, but I don't know for sure.

    I was thinking about mounting a hitch to carry a 200 lb scooter behind the TT, but the good folks here talked me out of it.
  • harley4275's avatar
    harley4275
    Explorer
    Dec 29, 2016
    As a simple stop to the bouncing bike rack on the back ...I screwed an eye bolts,one each side to the trim on the corner of the rea of he camper . Just drill thru the rubber trim cover and thru the corner trim into the 'meat' of the corner (alum or wood) and screw eye bolts in ...and then attach a rachet strap from one side eye= around the bikes =to the other side eye.
    Have had people drive behind me and saw no movement.
  • aftermath's avatar
    aftermath
    Explorer III
    Dec 29, 2016
    IBcarguy wrote:
    This topic comes up frequently. There are many that insist that it's not safe and many that don't. I installed the MnL Safety Struts and used my bike rack many times and haven't seen any evidence of bumper failure. The Struts seem to support it very well, and I haven't found any cracks on any of the bumper welds.


    And good for you. The OP simply asked if he could attach a carrier to his bumper. He did not talk about modifications so the answers he received were pretty good. You, by the sound of it, did not "just" attach the bike rack to your bumper.

    The issue here has everything to do with physics and something I believe is called moment of force. It is like using a lever to lift or move something quite heavy. When you have a lever of any length, the small force you impart on the end is multiplied, depending on how long the lever is, to a point that your small effort becomes quite large, large enough to move the weight.

    When you place 100 pounds behind the fulcrum it becomes a much larger force when it starts to move up and down. Think of the fulcrum as the place the hitch is attached. Think about what is going on behind your trailer when you hit a bump in the road or a pothole. It is no wonder people lose their bikes and spare tires. If you reinforce the bumper you can mitigate some of these forces but you should know what you are doing.

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