Tow Hitch Loads For Bike Carriers
Discussion
I've got an old Civic fitted with a towbar. Handbook defines a 50kg vertical load limit.
I want to buy a towbar-mounted bike rack (Strada DL3), total weight with bikes almost exactly 50kg.
Simple questions:
1) Even though the vertical load is still 50kg, it'll be located about 400mm behind the vertical axis of the towbar, giving a significant moment (lever effect). Is the max. vertical load figure primarily due to strength limitations of the towbar-body mountings, or suspension compression? If it's the latter, surely the vertical load limit should be de-rated to compensate for the lever effect of something rigidly clamped to the ball?
2) Are tow hitches designed to take this moment loading? Obviously, the're spherical to avoid this kind of load, and provide articulation.
I can't find any information on this on the carrier specs.
Thanks.
I want to buy a towbar-mounted bike rack (Strada DL3), total weight with bikes almost exactly 50kg.
Simple questions:
1) Even though the vertical load is still 50kg, it'll be located about 400mm behind the vertical axis of the towbar, giving a significant moment (lever effect). Is the max. vertical load figure primarily due to strength limitations of the towbar-body mountings, or suspension compression? If it's the latter, surely the vertical load limit should be de-rated to compensate for the lever effect of something rigidly clamped to the ball?
2) Are tow hitches designed to take this moment loading? Obviously, the're spherical to avoid this kind of load, and provide articulation.
I can't find any information on this on the carrier specs.
Thanks.
Do Honda sell a towbar mounted bike carrier for your model of car? At JLR we sell such things where they have been tested as being suitable for the car.
As you say the loading into the towbar is a turning moment rather than the point loading that it was primarily designed to take. So it puts different stresses into both the towbar and the mounting points on the chassis, potentially giving a different failure mode than it was tested for.
So if Honda sell one then it will have been tested as acceptable to work with your car.
HTC
Bob
As you say the loading into the towbar is a turning moment rather than the point loading that it was primarily designed to take. So it puts different stresses into both the towbar and the mounting points on the chassis, potentially giving a different failure mode than it was tested for.
So if Honda sell one then it will have been tested as acceptable to work with your car.
HTC
Bob
Bobhon said:
Do Honda sell a towbar mounted bike carrier for your model of car? At JLR we sell such things where they have been tested as being suitable for the car.
As you say the loading into the towbar is a turning moment rather than the point loading that it was primarily designed to take. So it puts different stresses into both the towbar and the mounting points on the chassis, potentially giving a different failure mode than it was tested for.
So if Honda sell one then it will have been tested as acceptable to work with your car.
HTC
Bob
Thanks Bob, I'm assuming if a carrier is TUV approved it will have passed any relevant safety tests.As you say the loading into the towbar is a turning moment rather than the point loading that it was primarily designed to take. So it puts different stresses into both the towbar and the mounting points on the chassis, potentially giving a different failure mode than it was tested for.
So if Honda sell one then it will have been tested as acceptable to work with your car.
HTC
Bob
I would only assume that if it has been TUV approved for your specific car. TUV is like the old British Standards, but for Germany.
So they will approve whatever you have against whatever standard you ask them to. It may be a great cycle carrier that will hold 2 bikes of a given weight, securely during a laid down shake, rattle and roll test carried out on a test rig. At the end of the test it will still be in one piece and capable of restraining the bikes.
At no stage during this test would the carrier have gone anywhere near a car to see if it will break the towbar or the car body itself.
As a very professional body (they are German) I am sure that they would not certify the carrier to be suitable for any particular car, unless they had tested it to a given standard on that specific car.
Only the manufacturer of your car would actually test the carrier on their car body. People don't realise that OEM accessories are more expensive than generic accessories because they have been fully tested and approved.
You may not get any issues with the carrier on your car, but only Honda would guarantee that.
Bob
So they will approve whatever you have against whatever standard you ask them to. It may be a great cycle carrier that will hold 2 bikes of a given weight, securely during a laid down shake, rattle and roll test carried out on a test rig. At the end of the test it will still be in one piece and capable of restraining the bikes.
At no stage during this test would the carrier have gone anywhere near a car to see if it will break the towbar or the car body itself.
As a very professional body (they are German) I am sure that they would not certify the carrier to be suitable for any particular car, unless they had tested it to a given standard on that specific car.
Only the manufacturer of your car would actually test the carrier on their car body. People don't realise that OEM accessories are more expensive than generic accessories because they have been fully tested and approved.
You may not get any issues with the carrier on your car, but only Honda would guarantee that.
Bob
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