TrailManor Owner's Forum - View Single Post

05-23-2011, 10:12 PM

I ordered the trailmanor bike hitch receiver and installed it in the garage a couple of years ago. I have my trailmanor backed into the garage now so I can't check the size of the attachment plate and bolt diameters so I will try and summarize from memory and give you some advice.

When I got the bike receiver and it said maximum load 100 lb I was quite surprised since it seemed very low. Anyway having used it for many times, with sometimes putting 3 bikes on my 4 bike carrier (say 130 lbs+ my 30 lb bike carrier = total 160 lbs)) with no problems. The bike hitch receiver attaches to the C-channel frame of the trailmanor. The 2 inch square box sections of the bike hitch receiver are very strong steel box sections going from side to side and are welded to a relatively thin plate (I would say no more than and perhaps less than 1/8 inch). It connects to the C-Channel trailer frame with a couple of gavanized bolts which from memory were between 3 and 4/8 inch in diameter and spaced at about 4 inches from top to bottom. Even a 3/8 inch diameter bolt should have a shear strength of 3000 lbs, so the weak point could be the thin plate of the bike receiver plate in bearing against the bolt. The mechanics of putting a motor bike out with its centre of gravity say about 20 inches back from the centreline of the bike hitch receiver attachment is that it will create a moment of 140 lbs plus the carrier weight (say 200 lb) times about 20 Inches that must be resisted by 2 bolts (one each side) over a moment arm of 4 inches plus the vertical load of the bike itself. This would equate to a static load of about 500 to 600 lbs on the bolt on each side. If you consider the dynamic effect of going over speed bumps and pot holes (say with an impact factor of 3) it might be possible to generate 1800 lbs shear in the bolts which should be okay. I can't remember the exact thickness of the bike receiver thin plate but I would guess that the weak point would be the bolt bearing capacity (strength of plate bearing against the bolt) against the bike receiver hitch plate. A simple solution to strengthen this aspect would be to install larger bolts, enlarge the holes in the thin plate and drill larger holes in the C-channel which you have to drill yourself anyway. Using larger bolts with helical spring lock washers and large plate washers and making the larger bolts tight should increase the bearing capacity of the thin plate.

Of course another way to load check it to see if the 200 lb bike and carrier is okay, is to get a couple of 200 lb men to simultaneously jump up and down in unison on the carrier (say 400 lbs x 1.5 load factor=600 lbs) and if that does not damage the bike receiver attachment then you are probably okay.

05-23-2011, 10:12 PM	#2
BigBear Guest Posts: n/a	I ordered the trailmanor bike hitch receiver and installed it in the garage a couple of years ago. I have my trailmanor backed into the garage now so I can't check the size of the attachment plate and bolt diameters so I will try and summarize from memory and give you some advice. When I got the bike receiver and it said maximum load 100 lb I was quite surprised since it seemed very low. Anyway having used it for many times, with sometimes putting 3 bikes on my 4 bike carrier (say 130 lbs+ my 30 lb bike carrier = total 160 lbs)) with no problems. The bike hitch receiver attaches to the C-channel frame of the trailmanor. The 2 inch square box sections of the bike hitch receiver are very strong steel box sections going from side to side and are welded to a relatively thin plate (I would say no more than and perhaps less than 1/8 inch). It connects to the C-Channel trailer frame with a couple of gavanized bolts which from memory were between 3 and 4/8 inch in diameter and spaced at about 4 inches from top to bottom. Even a 3/8 inch diameter bolt should have a shear strength of 3000 lbs, so the weak point could be the thin plate of the bike receiver plate in bearing against the bolt. The mechanics of putting a motor bike out with its centre of gravity say about 20 inches back from the centreline of the bike hitch receiver attachment is that it will create a moment of 140 lbs plus the carrier weight (say 200 lb) times about 20 Inches that must be resisted by 2 bolts (one each side) over a moment arm of 4 inches plus the vertical load of the bike itself. This would equate to a static load of about 500 to 600 lbs on the bolt on each side. If you consider the dynamic effect of going over speed bumps and pot holes (say with an impact factor of 3) it might be possible to generate 1800 lbs shear in the bolts which should be okay. I can't remember the exact thickness of the bike receiver thin plate but I would guess that the weak point would be the bolt bearing capacity (strength of plate bearing against the bolt) against the bike receiver hitch plate. A simple solution to strengthen this aspect would be to install larger bolts, enlarge the holes in the thin plate and drill larger holes in the C-channel which you have to drill yourself anyway. Using larger bolts with helical spring lock washers and large plate washers and making the larger bolts tight should increase the bearing capacity of the thin plate. Of course another way to load check it to see if the 200 lb bike and carrier is okay, is to get a couple of 200 lb men to simultaneously jump up and down in unison on the carrier (say 400 lbs x 1.5 load factor=600 lbs) and if that does not damage the bike receiver attachment then you are probably okay.