hitch mounted bike rack weight limit

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salty
Participant
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I just installed a hitch on my wife’s car – it’s supposed to be a Class II hitch with 300# max tongue weight.

I’m trying to figure out is what that translates into as far as bike rack capacity. It seems like the “arm” being so far behind the hitch has to impart a higher effective weight? I found some talk about that searching the net but nothing too definitive; what I’d really like is some sort of formula.

I bought a 2-bike rack and don’t have any real concern about using that – overall weight will be maybe 75#. I’d like to have the option to take 4 bikes which will be more like 150# and obviously the bikes will be further behind the car.

Anyone have any experience with this? Am I just worrying too much?


brian j
Participant
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Don’t forget to factor in the weight of the rack itself.

Sorry, that’s not helping, is it?

From what I’ve read, you aren’t likely to damage the trailer hitch, but you may adversely affect the handling of car.

There’s also this, that talks about what hitch extenders do to the calculation of tongue weight.


Drewbacca
Participant
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“Ignore the length of the bar or the string from which the load is hanging. These are irrelevant to calculating the weight of the load. A difference in bar length will only change the distribution of the force along the bar, not the total force itself.”

http://www.ehow.com/how_7332674_calculate-hanging-load-extended-bar.html


StuInMcCandless
Participant
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This is an important topic, and I don’t recall us ever discussing it on the board in any detail (though I could be wrong).

I’ve never looked into getting a hitch exclusively for a bike rack, and no car I’ve ever owned had a hitch, so I’m entirely in the dark here. Nor have I ever needed to tow a trailer, or even thought about it. But with a car that’s 12 years old and 180K on it, I do need to start looking.

Can cars (not SUVs, not trucks) come from the factory with hitches? Can they be so equipped coming off the lot? Or is it always after-market?

And I do have to reiterate the first question — how many bikes can or should I consider carrying on a rack?

Then, too, capacity: I’m guessing 80% of the time I’ll carry just one; 19% of the time, two; but there’s that nagging 1% where I might need 3 or 4. Do I buy for the 99% or the rare 100%?


orionz06
Participant
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The receiver can support 300# at the standard ball location. Extending weight beyond the location of the ball (that is not there now) will create a lever and the effective load will be reduced. In the grand scheme of things you aren’t really reducing the capacity by much and it will be negligible. The bigger concern is height and hills. Make sure you are aware of where the bikes are and how going onto steep driveways can damage bikes. I have seen too many bikes get destroyed when someone switched to those type of racks.


salty
Participant
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I was more worried about damaging the car/hitch due to the weight but it sounds like that’s not a huge issue. I was assuming 150# for 4 bikes @25# each + 50 for the rack. The handling and clearance issues are certainly something to be aware of but shouldn’t be a deal-breaker.


salty
Participant
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Stu, I went back and forth on that and finally decided on 2. I didn’t want to leave it on the car all the time but wanted my wife to be able to handle putting it on if I needed a ride home. So, I decided on a Thule helium which is aluminum and pretty light (21 lb).

But, like you said, there are times where 4 would be useful. I’m hoping to make it to the Dr. Varacallo ride and it would be much more efficient if I could fill the car up. MS150 is another example. Or even just hitting some trails with some friends who don’t want to ride on the roads to get there. So, I’m not sure, I may yet buy a 4, assuming my car can handle it.


Marko82
Participant
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@salty, having pulled many a trailer over the years – don’t worry too much about the weight. Look at the car tires in relation to the top of the wheel well. When this space is reduced by half, that’s about the max weight you want to carry. This is the distance with no weight inside the car too. So if your carring your lead-ingot collection, that will reduce this space too, and further limit the hitch weight. Your basically limited by the cars suspention, but there’s upgrades for that if you are going to be carrying a lot of weight on a regular basis.

Also, take orionz comment to heart. You can bottom out that rack on speed bumbs and divot driveways even with no weight on it.


salty
Participant
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Hm… well, that may be one good thing about the hitch I had to buy for the Mini. The car is actually too low to mount a normal hitch. This thing I installed is a bit higher than it might be on most cars, it goes through the bumper – although it does stick out a bit further.

Not that you can really tell from this crappy picture, but:

I actually kinda wish the u-shaped part with the hitch on it could mount upside down for more clearance, but it’s designed not to.


Nick D
Participant
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What I would be worried about most is the mounting points on the car where the hitch mounts. I suspect that most of the damage will be at those locations. Though, depending on how it mounts, it is probably just stretching holes, but it could be worse like separated seems.

Although, theoretically, 150 lbs of bikes is 150 lbs of bikes, whether 2 ft. from the hitch or 20 ft. from the hitch, the way the load is distributed on the cars’ mounting points drastically changes.

I have seen hitched that mount mostly to sheet metal parts (like the bitch for my car–two holes are drilled into the sheet metal of the spare tire well, and two bolts hold steel plates on both sides of the sheet metal.) bend panels and even separate the whole panel at the seems (keep in mind that a panel like a spare tire well is usually only spot welded and the seam is covered with seam sealer. Some seams on some newer cars are only bonded with adhesives).

If it mounts to the sub-frame (or a factory reinforced part of the uni-body), I wouldn’t worry too much about having 125 lbs of bikes on there. Even if you do damage, it will probably be minor enough that you’ll never notice (unless you go to remove the hitch).


salty
Participant
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The way this mounts is you unbolt the rear bumper, put this thing on the same studs then put the bumper back on, so it’s sandwiched between the bumper and the car. So, that part should be pretty sturdy.

It does bug me that there’s also a plate that bolts to the spare tire well which is just sheetmetal. So, it seems like they’re anticipating some flex but like you said that is not going to support much weight at all – it makes me wonder why it’s necessary. Hopefully it just helps to stabilize things and doesn’t really support the load.


Nick D
Participant
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It is a factory part, right?


Jacob McCrea
Participant
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@salty, from what you described, and from what I vaguely recall of a friend’s Mini Cooper with a hitch, the hitch is mounted better than what’s needed for 4 bikes. The “plate that bolts to the spare tire well” helps to prevent the hitch from rotating downward, especially if the “sandwiched” mounts attach to gas-filled shock absorbers. You might check that area for sheetmetal distortion after hauling 4 bikes if you’re really worried. If you regularly “max out” the hitch capacity, and I doubt it, you might want to look into reinforcing that area. The thing to watch out for is exactly what Nick described – poorly designed mounts which place the load on thin sheet metal and distort it.

After years of heavy abuse, I actually ripped the last 4 inches of the frame rails off of a Toyota truck. I had to reweld and further brace the frame with heavy 1/4 inch angle iron. This was due to having a heavy trailer and, more significantly, using the truck as logging equipment on a friend’s farm. Bottom line: the hitches will, within reason, take whatever you throw at them, but the mounting points need to be strong enough for what you want to do. Also, Marko is correct – you’ll typically max out your car before maxing out the hitch’s strength.


salty
Participant
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nick – it’s aftermarket, they just have arrangements with the dealerships to install them, but i don’t take that as being endorsed by the factory.

jacob – cool, that’s true and it would be very easy to see if there’s any bending or other damage in that area. There’s no shocks or anything where the bumper attaches – maybe I should have taken a better look while I had it apart but it’s definitely attached to structural parts of the body.


Swalfoort
Participant
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@stu – yes, yes and yes. I just bought a new car, and went through some of the same decisions. Cars can come equipped with a hitch. (There are two sizes of hitch mounts -maybe 1.25 and 2 inches (don’t quote me on the sizes – so know what you are buying or what you have before investing in a rack to fit it.) Many dealers can add a hitch mount to a car that does not currently have one, or it can be done aftermarket. It is a pretty simple process, but Nick’s comments and concerns are appropriate. Some bike rack models fold down, with the bikes mounted on them, to permit access to the trunk or hatch. That’s a handy feature. All that said, I am experimenting with a new truck rack. I had an old Graber model, and figure that they must have gotten better in the 20 years since I bought that one. I invested some real money and bought a Thule Raceway Platform 2. The rack mounts (and locks, more or less) to the truck (or in my case hatch), and the bikes are then clamped as with a normal rack. But, the added feature is a platform element, which locks the wheels in place too. I am hoping it will add stability. It certainly adds weight. I am using it for the first time this weekend. Wish me luck — which means that the bike, the new car and I all come home, with no major scrapes, bruises or dings.


salty
Participant
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So I had my first test of this today, and it worries me. The bikes were bouncing around quite a bit. But, as far as I can tell, most of the motion is the rack itself, it seems like it’s just designed that way? I mean the vertical “post” part moves around relative to the horizontal part that connects to the receiver. Mostly up and down but some side to side as well. The rack is a Thule 970xt – very well reviewed and not cheap.

Anyone with experience with hitch mounted racks – is that normal? I am still worried the rack sticks out way behind the car. I may buy the “mini fini” rack that mounts directly to that carrier, I bet that will bring the bikes almost a foot closer to the back of the car. Maybe I should have just done that to begin with, but I told the guy what I was planning to do and he didn’t say no. I guess I just can’t quite figure out if the bouncing is due to my particular setup or if its just “normal”. Maybe some combination of the two, the hitch part does move a bit and that long of an “arm” just amplifies the motion.

It worries me way more than the rack I used to strap to my hatch ever did.


brian j
Participant
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The hitch rack we have bounces quite a bit, too, though it is caused by play in the hitch/rack interface and not the rack itself. I used to worry about it, then drove to Connecticut with three bikes on it, and promptly stopped worrying.

Our hitch-mounted luggage box came with a little u-bolt and plate mechanism that removes much of that wobble from the box setup. Perhaps that might help? Or does the Thule include such a doo-dad?


salty
Participant
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Yeah, there is kind of a wedge mechanism that gets rid of any play in the hitch interface itself, that is not moving. Its the joint between the two parts of the rack (which is hinged to allow you to lower the vertical bar to access the hatch) that seems to have a lot of play.

Good to hear it’s not completely unexpected to have some movement though… but it seems like a lot to me. Btw this was with 2 bikes, haven’t tried just 1.


StuInMcCandless
Participant
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IIRC the conversation in the parking lot after the Try-A-Bike Jamboree the other day, with reddan and the gent from State College, the greater concern is metal failure on the car where the hitch attaches.


brian j
Participant
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I probably have a bit of play in the joint on my rack (I have a similar hinge), but, truthfully, my rack, a Mopar, is built like a tank.


AtLeastMyKidsLoveMe
Participant
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I have an old Hollywood rack mounted into my truck’s receiver hitch. It is constructed of 2″ square tube steel. It is as heavy as f*ck. And, it was designed for a vehicle I no longer own but which had a rear-mounted spare tire, so the whole deal projected even further back. It is intended for three bikes, but I have had four on it.

It does bounce a little, but that’s more the strap system than the steel – it is snug in the receiver. And it is certainly not the tube steel flexing.

I guess it’s a little of apples and oranges, but I’m generally the paranoid “oh crap, that f*cking thing is going to fall off my truck” type, and I’ve arrived at the conclusion/rationalization, that it’s a big-name brand, there are a lot of them around, it is as heavy as f*ck (did I say that already?), and it is probably over-engineered.

So if yours is heavy as f*ck, I wouldn’t sweat it.


salty
Participant
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Well, the one I bought (Thule helium) is actually light as fsck, that was the main selling point… so maybe that is to be expected.

The main movement is in the joint so I have to imagine it was designed that way, I mean I can make it move by hand without applying too much force at all. But, the hitch part itself (which is 2 parts, see the pic above) does move some as well which bugs me. It is held to the frame with 8 bolts using the bumper attach points, so i don’t know what exactly is flexing there. And it just amplifies the movement of the rack.

I think I’ll give the non-receiver rack a try, even if it ends up costing me some money it will be worth it for the peace of mind. I just don’t like how far behind the car this setup ends up putting the bikes, even forgetting the motion.


snakeguy
Participant
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My girlfriend uses this Sportrack (http://www.sportrack.com/a30704) model hitched to her 2004 Grand Prix. I’ve used it with 3 cycles and wouldn’t hesitate to add the 4th if necessary. I see it states “available in Canada only”. She has purchased 2 of these from the U-Haul on Rt8 in Shaler.


snakeguy
Participant
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martinbrown4446
Member
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i would suggest taking advice from any towing service provider near you, whenever I need any guides about towing so I just ask from my Motorcycle Towing Service provider that guide me very well.


Eric
Member
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Totally a bot. This one was programmed better than the others recently


StuInMcCandless
Participant
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The thread is useful, in that the car I ended up getting in 2012, and put a hitch-mounted bike rack on, is now nearing the end of its useful life, so I need to revisit this topic. So thanks, bot, for digging it back up for us.

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