hi all, i am sure this has been asked before. my brother is building his own rig. bike weighs 500lbs. platform can weigh whatever is needed. he wants to know minium width bike wheel to sidecar wheel for safe handling.thank you pat.
The length of the motorcycle wheelbase is a factor here too.
On a medium weight rig I have generally used the center of tire to center of tire track to be not less than 42 inches and not more than 46.
I generallyroll the bike onto a piece of string so the both tire are centered on the string. Then measure from that point to the center of the hack tire is how I measure.
A full heavy bike with a sidecar to match I like 48 to 50 inches.
Axle of the hack should be 8 to 11 inches ahead of the bike rear axle. My own preference.
For toe in I put a straight edge along the hack wheel and measure from it to the string at the rear axle and at or close to the front axle.
The front should measure one half to one inch less than the rear measure as a starting point. Final adjustment is arrived at by test riding the bike
to note any side pull. Lean out is adjusted by the same test riding.
I like my bikes to have a neutral steer,( no side pull ), at 55 to 60 MPH.
A properly adjusted rig is a joy. An Ill adjusted rig is dangerous.
thanks phelonius, the wheel base is 58 inches. 81 650 yamaha. pat
Please don't expect the setup of your rig to be the same any other, even it appears to be mechanically identical. I'm VERY nervous when folks give advice that calls for particular numbers instead of places to start your own testing.
I have no quarrel with shooting for a particular width but you should know why and what the consequences are. I'm not a physicist but it doesn't take one to understand the forces at play here. You've probably seen the Pontiac commercial that said. "Wider Is Better". Well, wider rigs are less likely to pick up the sidecar wheel, generally that's a good thing. Here's what it costs you ... Newton's First Law of Motion, "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force." On a sidecar rig that means when you start off, the inertia stored in the sidecar will cause the rig to pull towards the sidecar. This is perfectly normal and after you've been riding for a while you'll get used to it and even begin to use it to help you in turns. The opposite is equally true, when you slow down the inertia stored in the side car will push the rig away from the sidecar. Again, you get used to this to the point that after a while you compensate automatically. THE WIDER THE RIG, THE MORE YOU WILL EXPERIENCE THE EFFECT. Adding a sidecar brake will help with the effect when slowing but nothing will help when you're starting off. The majority of rigs do not have sidecar brakes and I have two rigs, one with a sidecar brake and one without, and I really don't have a strong opinion on the brake or no brake issue. Both rigs are fun to drive.
Please use actual measurements that folks give you as a place to start and do your own testing to arrive at the best set up for YOUR rig. This is just my opinion, you'll hear others.
thanks al, all we are looking for is a place to start. my brother is 600 mi. from me and no acess to internet. he calls me once a week for info. he wants to start at 38in. track and go from there.was just curious if there is a definate to narrow point.obviously there is,but looking for wisdom of been there done that.thanks agian for your input. ps,its very seldom one shoe fits everyone in the room. pat
I am not saying my measurements are best, only what I prefer after 10 sidecar rigs in the years from 68 to present. Half of them I built from scratch.
I still have two. One is a road machine with no sidecar brake, and the other is a dual purpose machine,(on or off road), with a brake and variable linkage
for better off road control.
An 81 650 Yamaha with a wheel width of 58 inches is as wide as it is long. To my experience this is not good for general handling.
Look online for any information about building sidecars and educate yourself before you begin welding.
There is a guy on this forum named Sweet who has built more sidecars than any of the rest of us, ask him for help.
phelonius,thanks for getting back. the wheel base is 58 inches on the bike. i think mike is going to start at 38 inch track widte and adjust from there.he will be using 7.5 inch wheel lead to start.thx pat.
While not giving specific amounts may be the safest response to the questions, shooting for a track width of 38" centerline to centerline even on a small bike like Yamaha 650 cc would be far to narrow and I doubt the driver would be able to maintain three wheels on the ground in the slightest right turn especially a novice driver. Shoot for an overall outside of tire to tire of around 50" and after some experience he may want to tighten it or lengthen it some. I piloted a Yamaha XS650 with a Velorex sidear for about 20 years and finally finished adjusting and settled on 49" outsideto to outside, I use no ballast.
Phelonius, You're projecting. I'm not saying anything about your numbers, just the warning I try to post every once and a while when I see a noob looking for guidance. Too often someone reads a post and [hoping to strike gold the first time] follows it without realizing that the number isn't chiseled in stone.
After saying that, I'm about to deny it in a way... I agree that a 38" track is really narrow, really really narrow and I wouldn't even consider it. Please note, I'm not saying how wide it should be, just that I wouldn't suggest a track that narrow. I know that sounds less helpful than giving a definite answer, particularly when you're a noob and looking for concrete info.
There is a rule of thumb for sidecar weight compared to bike weight. Generally the sidecar should weigh at least 1/3 of the bike. NOT a hard and fast rule, just a starting place. The test I use is to have the driver stand on the left peg [assuming a sidecar mounted on the right] with his/her right foot and then try to pull the sidecar off the ground by leaning out and pulling on the bars. If it comes up easily you will probably have a rig that flies the car way too often. If it comes up a bit and then settles back you're on track. If it won't come up at all, it isn't an issue but it might be an handful on starts and stops. While we're on "Rules of Thumb", a good starting place for wheel lead is equal to the diameter of the rear tire [not just the rim].
Again, just a starting place.
cadypat wrote:"hi all, i am sure this has been asked before. my brother is building his own rig. bike weighs 500lbs. platform can weigh whatever is needed. he wants to know minium width bike wheel to sidecar wheel for safe handling.thank you pat."
Track width (CENTER OF BIKE TIRE TO CENTER OF SIDECAR TIRE) if narrow will create instability without an active passenger. We will typically not do a rig with a track width less than 48". Typically most end up around 54 of so inches. YES... 38" is very narrow indeed. Obviously when turning toward the sidecar the sidecar wheel will want to rise. Track width comes into play here of course. Leverage? Yes....try to pick a sledge hammer with two fingers up by the head.....yea pretty easy. Then pick it up by the end of the handle...not so easy. So it goes with track width.
There is a little more to I than just weight distribution alone.
Think 'tip over lines'. One tip over line runs through the front wheel and through the rear wheel of the bike. This tip over line comes into play when turning toward the sidecar.
Another tip over line runs from the sidecar wheel to the front wheel. This one comes into play when turning away from the sidecar. Now...as track width increases the angle of this tip over changes and allows more stability in turns away from the sidecar. Result? Too little track width will allow the rear wheel of the bike to unload easier. I have flipped the bike over the sidecar before and it does very little for the old fun meter.
So...I would shoot for absolutely no less than 48" and would rather see it around 50 to 52 minimum.
Wheel lead (how far the sidecar wheel axle is ahead of the bike rear axle) can be subjective. Again, think tip over lines. All in all somewhere between 9 amd 11 inches would be okay. More lead equals more stability turning away from sidecar but harder steering. yep it's a trade off.
Toe in? Stright wdge on sidecar wheel and on rear wheel of bike.(not on front wheel at all) Measurement taken just in front of fron twheel and just behind rear wheel of bike. Probably a half inch to 3/4 or so. Less is best. Too much toe in will do nothing except create more tire wear. Toe out usually does make the thing pull to the right. Th eless toe in the better.
Lean out is how much the bike leans away from the sidecar. THIS is where you adjust tracking on almost all rigs. rule: Lean left to go left and right to go right. When adjusting lean out recheck toe in because if lower mounts are not the same distance from the ground and from the centerline of the bike leaning the bike in or out will change toe in.
Tilt? This is a fine tuning adjustment that tilts the whole rig to the left or the right to adjust tracking variables due to road camber, loads in sidecar etc. Some rigs have and electric tilt which is cool and can be adjusted while in motion. Some have a simple manual tilt which is good too but has to be done by hand. Some rigs utilize an antiswaybar which is a self compensating device up to a point. You may also be able to adjust tilt with your shocks to a point.
Sorry for being long winded. Build it safe...and as, good friend, the late Hal Kendall used to say 'when in Doubt build it stout'!
Freedom Sidecars.com....and check out our facebook page 'freedom sidecars' 🙂
i really want to thank everone forthis input.this is what i needed to help him figure out his build.we will do it safe and you all have given us food for deep thought.thx pat.
Just a note here, Ural sidecar specs list the track width as 52 inches. They measure from outside edge of bike tire to outside edge of sidecar tire.
This would make a center to center measure of 48 inches. I remember that my old Dnepr had about 44 inches. Either of those factories have put together more rigs than all of us on this forum put together.
Therefore I submit that their measurements are a good starting point. One of my rigs many years ago was a 650 Yamaha vertical twin carrying a Bingham hack.
I pretty much used the bingham mounts except I welded some receiver lugs to the frame of the bike. I don't remember the measurements but proportionately it looked about like other sidecars of the day, Harley
excepted. Harly had their own formula for mounting.
Phelonius - 2/23/2015 12:01 AM
Just a note here, Ural sidecar specs list the track width as 52 inches. They measure from outside edge of bike tire to outside edge of sidecar tire.
This would make a center to center measure of 48 inches. I remember that my old Dnepr had about 44 inches. Either of those factories have put together more rigs than all of us on this forum put together.
Therefore I submit that their measurements are a good starting point. One of my rigs many years ago was a 650 Yamaha vertical twin carrying a Bingham hack.
I pretty much used the bingham mounts except I welded some receiver lugs to the frame of the bike. I don't remember the measurements but proportionately it looked about like other sidecars of the day, Harley
excepted. Harly had their own formula for mounting.
A Ural sidecar weighs around 200 pounds. They are what they are. Not sure what the bike itself weighs. Not really a high speed sidecar outfit.
Yes, Harley sidecars....we have mounted a few. I have the Harley mounting instruction manual. It Calls for lean in and not lean out. Why? NO SUSPENSION TO COMPRESS OF THE SIDECAR. So when the rider gets on the bike only the bike suspension will compress some. Is the manual correct? Only if the final road manners are suitable to the rider...LOL. Some have said:" Gotta be right it is setup to the specs in the manual and all rigs pull to the right" WRONG! We have adjusted some and made them track quite well. So the basics are the basics. Lean the bike the way you want to go as far as setup goes.
Track width on a Harley sidecar? 50 to 52 inches.
Sidecar weight: 257 to 283 depending on model.
Note: Motorcycle frames are not all the same. Some are quite thin walled actually and some are not. Welding on the frames is something that can create issues or may not. We do not do it but rather use a full or partial subframe assembly to mount the sidecar too which is a bolt on. This adds strength to the whole assembly and takes away any question that can be related to welding. It also allows mounts to be placed for good triangulation and ease of adjustment.
Absolutely not desiring to be contentious here nor be difficult just trying to provide some food for thought. Sidecars carry precious cargos and it is very important to lean toward 'knowns' that are time proven when talking about various bikes. Even though mounts may be welded on one bike from the factory does not mean it is a 'given' that welding on another bike frame will work out well.
Al Olme - 2/22/2015 10:30 PM
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There is a rule of thumb for sidecar weight compared to bike weight. Generally the sidecar should weigh at least 1/3 of the bike. NOT a hard and fast rule, just a starting place. The test I use is to have the driver stand on the left peg [assuming a sidecar mounted on the right] with his/her right foot and then try to pull the sidecar off the ground by leaning out and pulling on the bars. If it comes up easily you will probably have a rig that flies the car way too often. If it comes up a bit and then settles back you're on track. If it won't come up at all, it isn't an issue but it might be an handful on starts and stops. While we're on "Rules of Thumb", a good starting place for wheel lead is equal to the diameter of the rear tire [not just the rim].
Again, just a starting place.
That 'test' is excellent and should be used by anyone who is planning to operate a sidecar rig they are not familiar with. It applies to stability in turns toward the sidecar. All rigs are not the same.
If one is a practiced sidecarist it is still good to do this simple test. Picking up th sidecar on a lighter rig is no big deal and is easily controlled if one is diligent enough to practice.
Left handers, however, can bite quick and hard. Light bike and heavy sidecar combo.....maybe minimal wheel lead? Bad combination in lefties. Some of the adventure bike setups can be a little on the tipsy side as well due to the high center of gravity etc. Don't want to overstate this but we should all be aware of it. I have heard some say: " You can do whatever you want in left turns and not worry about it"....WRONG!! Just wrong.
Practice is the key and one can never increase their skill envelope unless they dedicate themselves to practice in a safe place just a little at a time above their present comfort zone. Most issues arise when one gets into an area where they are above their present skill level. We are all learning and the process should never stop.
I have to agree with Claude about welding on the frames of bikes. That is why the construction of the frame is a large consideration in my choice of bike to purchase.
For instance, I really like the Yamaha SR 500 series but welding on a frame that is also the oil tank is not wise.
Yes I have built subframe for one of my bikes, it was the DR 650 E that carries a Ural. The hack is a bit heavy for that bike but it works well except that being a tall rig
it is hard to handle in a strong crosswind. Kohala winds can be a bitch especially from Upolu point to Kailua Kona. They sweep around Kohala mountain and funnel
through the gap between Kohala and Moana Kea. They can be hazardous. A low heavy rig is much better there.
