Advantages in front end modifications?

So many questions so little words 🙂
Okay..steering dampners are to take the headshake out of a rig. Many sidecar outfits will exhibit a slight headshake typically at slower speeds. Some are worse than others. Th edampner will help this from being such a nuisense. Now...what causes the wobble or headshake? Sometimes it is just the geometry of the rig and sometimes it has more to do with such things such as play in the swingarm or steering head bearings or it can be as simple as a tire pressure adjustment being needed. There are many dampners installed on rigs that may not really have needed them if the the steeringhead bearings would have been tightened up. Most outfits are happiest if the steering head bearigs are a little tighter than normal. I like to have mine so the front wheel , when jacked off the ground, will have to be nudged slightly to turn away from straight on. If it just falls to the side the bearings are too loose. This is an easy adjustment and the cost is only a little bit of time. I have ridden sidecar outfits that did need a dampner for sure and others that could have easily gotten away without one. I have ridden outfits that had a leading link installed but the dampner used was so stiff it took away the advantage of the link anyhow. We have been fortunate to have yet to need a dampner on one of our personal rigs. Yes they do a little dance at a certaim speed but it is somethig you don't even think about after a while if you keep your handa on the bars.
Most front end mods are done to reduce the trail. Trail can be though of as beingsimilar to castor in an automobile. Reducing it make steering easier. There are many ways do this from adding a leading link front end, to one of the triple tree modifications , or leading legs to name a few. The leading links are probably the priciest of the bunch with the exception of center hub steering which is a whole 'nuther story. A link front end is also nice in that it makes the whole front end assembly much more rigid and it takes away the 'stiction' related to conventional forks. Many links also have a sort of built in anti dive due to the geometry involved. They may even rise up on braking.
There are some budget ways to reduce trail as well as the above. On is to go to a smaller diameter front tire. one is to run the fork tubes up throug the triple trees.(Be careful on this one with clearances etc...I put a hole in a goldwing radiator ones through my own carelessness..it did steer easier though..lol). Ther have been modes done with pinch blocks to move the fork tubes out in front of the triple trees and there has been some success with simply swapping to another fork tube assembly from another bike.
Car tires on the front are, in my opinion, not nearly as beneficial as on the rear but if the rolling diameter is decreased the trail will be reduced too. For instance a motorcycle front tire on 19" rim may be 26" diameter. If the wheel was switched to a 15 " car rim with a 135R15 tire on it then the diameter may be 23 to 23 1/2 inches..yes an improvement. Car tires on the front can be succeptable to following ruts on the road though which can be a nuisence. This trait may be eliminated with air pressure adjustments. Some tires are more sensitive than others. The width or the tire and also the aspect ratio make different tires react in various ways.I do beleive a car tire on the rear is a huge benefit butthat is another story.
To start out I would suggest going with a stock setup. Make sure the steering head bearings are snug. Maybe run the forks up through the triple trees slightly and maybe mount some wider handlebars for more steering leverage. On a properly setup outfit the steering will seema little hard at first but as a new rider gets away from the initail death grip on the bars and learns to realx at the helm he will find that stock isnt too bad...for a while anyway:-)

Hi Claude;

Thanks! Your advice to go first with the stock set-up seems on the money. I'll do that, and if I see some kind of problem I'll pay closer attention to sidecar set-up, tire pressures, moving front forks upward in the triple tree and other things.

I currently use sport-radial tires and I suspect my tire life mileage will fall off dramatically (and it isn't all that great now....), so will most likely replace those with Dunlop Elite 491's or their equivalent. Maybe that will serve nearly as well as automobile tires....

My goal, perhaps unrealistic at that, is to be able to remove and re-attach the sidecar more or less at will, giving me the versatility of having both a solo bike and a sidecar outfit.

Of course, time will tell....

Oh yeah, one other question if I may; the manufacturer of my sidecar offers a seat belt option. And it would be easy enough to weld brackets to my sidecar frame and add a seat belt on my own. Is a seat belt recommended? Or is it a potential problem?

Thanks again!

Sahagan

I have had decent results with the Dunlop491s on sidecar outfits (Not 591s though!).
If you want to use the same bike for sidecar and solo it creates a pretty big compromise in what you can do. I think you may find that sidecars can be quite addictive. As you begin to see that a mod here and there will improve your sidecar experience the bike may be transformed, in time , futher and futher from a solo machine. Yes, there are some who switch a bike back and forth but the potential as a really good sidecar tug will not be as high on the scale as it could be.
Seatbelts? It may depend on what you want to use them for. If it is to secure a child from climbing around it is a good thing. If you are relying on it for a real life saftey feature in a crash..well it may help some depending on the circustances.
When you go to the GAP a passenger operated ejection seat may be more appropriate.
Claude 🙂

As usual, Claude got all the basic points laid out pretty well in his earlier post. Since you've said that you want to use your bike for sidecar work and still "go solo" from time to time, the conversion to a leading link front end is probably not a good idea. There are some leading links that are adjustable and a leading link is fine on a solo bike with appropriate trail. The cost isn't justified in your application. The thing that is usually left out when folks talk about leading links is the extra strength that the link affords to deal with side loading. Telescopic forks are built to deal with stress that is applied in line with the forks, on the straight away, that's vertical, when you lean over in a turn, the force is still applied in line with the forks so the stress is still essentially in the same plane, relative to the bike. When you use the telescopic forks for sidecar work, they are asked to deal with stress from a new direction. Since sidecars basically don't lean in a turn, there is side loading on the front end. Telescopic forks aren't designed to deal with force force applied from the side. All that said, most forks will deal with the situation just fine and for a bike that will see duty both as a tug and a solo, they are the best all around solution. For a dedication sidecar puller, leading links have a clear advantage. Of course, all that is my opinion...you'll hear others.

I spoke with Pete Larsen today at Liberty Sidecars about the subject of radial tires,plus using his solid aluminum 15" rim.
He pointed out that the changes depend on the rig, the type, and amount of riding done per year(it can be a costly modification).
If you are considering taking off the sidecar for solo riding auto tires are not really recommened. The same holds true for square tires.
The real advantages to radial auto tires include traction, longevity,and they are very cost effective(lasting up to 20,000 miles).
At the end of the discussion we decided to stay with stock rims and the Dunlop 491s'on my harleyFLSTC/liberty sidecar.
In addition to leading fork unit some bikes have a raked triple tree unit to reduce trail.improve handling and make steering more effortless.

>>I spoke with Pete Larsen today at Liberty Sidecars about the subject of radial tires,plus using his solid aluminum 15" rim.
He pointed out that the changes depend on the rig, the type, and amount of riding done per year(it can be a costly modification).<<

The idea of converting a rig to utilize car tires can be based on various things. The most sensible reason, or justifiable reason, would be one of economics. The economics of it may be more apealing to some than to others. The economics of it, in my opinion, applies more to a rear tire conversion than a front tire. Front tires tend to wear well anyhow so it is not justified to make the switch nearly as much as with the rear tire.
Good quality rear wheels can be had from various suppliers. EZS (Through Pete Larson at Liberty Sidecars), Lowell Neff (Bmws only I think), H T Wheels (Harry Tarzain 814-349-2414) and others as well as some independant wheel makers such as Norm Potruff and others.(please excuse me if any are left out here as I am sure they are) Are these expensive? Well..we must evaluate cost versus value. Tire wear is a huge factor to consider.Harry's wheels ,for instance, run from a little over 600 bucks and up dependant upon the bike and some other factors.Others may be much more costly and some may be a little less. The value factor comes in when tire wear is considered. A new 491 Dunlop may cost 125 dollars and up. The 165R15 auto tire that I just bought for the rear of the BMW outfit cost 35 dollars at Pep Boys Auto parts.This size car tire can also be picked up just about at any tire shop. (Keep in mind that some car tire sizes used on some conversions are not this easily located..The 135r15s I have on our wing project for instance usually has to be ordered from coker tire or somewhere).
Okay..only you can do the math from your tire wear experiences on your rig but it goes something like this..
A Dunlop 491 costs 125 dollars and goes for 8,000 miles.(may be a little more or a lot less)
A 165R15 costs , say 40 dollars, and goes for 20,000 miles.(May be a lot more or a little less)
Lets change the figure for the car tire to 24.000 to make this easier.
The motorcycle tire may get replaced three times for one time on the car tire.The car tire , dependant upon size, is readily availble and costs less than the bike tire.
125 BUCKS X 3 = 375 DOLLARS...Oh heck you get the picture. I dont have a calculator here but if we begin to weigh the costs versus the value of the conversion it makes the 'value' of the money spent become more real.This is especially true if a sidecarist does a lot of miles per year.
Typically we do 10-15,000 a year. (This last year being the exception with only about 8k being on the clock)..anyhow I sure felt that the conversion was worth the money. The car tires look neat too.

Claude
BMW K 100 (165R15 rear/135R15 front)
78 Wing project bike (135R15 front and rear)
79 XS1100 (Avon 3.50x10 sidecar tire front/ Dunlop K491 rear)

The key as Claude points out is mileage/year.
If you intend on putting the mileage on one rig as claude eludes to,the return on conversion is much more favorable then someone putting on 5,000 miles(or less)per year on a particular rig.
I was also incorporating the cost of the rim that is sold by liberty sidecars(1,195.00 plus shipping) into my equation. $1,200.00 still buys alot of Dunlops!
In my case I try toget 10,000 miles in a season but I have two rigs and a solo cruiser sharing those miles.
Thats the fun about riding and paticipating in these forums everyones needs are different yet we share a common interest and everyone learns something. There are alot of ways to skin a cat!

Getting back to the original comment on why someone makes these modifications to the front(and rear), smaller rims and lower profile radial tires will lower the rig and its center of gravity. This should make the unit more stable for aggressive driving.

>>Getting back to the original comment on why someone makes these modifications to the front(and rear), smaller rims and lower profile radial tires will lower the rig and its center of gravity. This should make the unit more stable for aggressive driving. <<

Short comment..right. longer one depends on the rig..suspension being able to handle the 'agressive driving' etc. Lower is better typically though...of course if Baja is a destination there could be problems.
Smaller dismeter tires also provide better overall gearing which is a big plus.
Claude

Hey Folks;

I hadn't considered the side forces to the front forks, but it makes sense. Would the aftermarket devices that clamp on the forks (I forget just this moment what they're called, but SuperBrace makes them for instance) be a worthwhile addition? It seems to that would also strengthen the forks from the side as well....

And tires? One of the main reasons I haven't considered an FJR1300 is the terrible tire life there. And I have to push it to get better than 8,000 on my Concours. I do around 16-18,000 miles per year, and suspect that will grow (I know for a fact tire prices are growing) with the sidecar, but still and all, I hope to be able to maintain the versatility that can be found in being able to revert to solo bike if need be. I sometimes travel long distances by myself....

Claude was kind enough to address the seat belt option, but does anyone else have anything to add to that? Its an easy thing to add, but is it a desirable thing to add? It seems to me the passenger could be sent forward into the sidecar 'dash' at pretty high speeds in some instances....and then again, it could lock someone in when getting out would be better.

Thanks!

Sahagan

Sahagan,

Seatbelts; We've added seat belts to both my rig and the wife's, in both cases they are just bolted through the fiberglass of the car floor. I DO NOT consider them safety equipment. If the sidecar is involved in a major wreck I feel the sidecar fiberglass would probably be in a million pieces, so there is no advanatge to staying in the car. If the seat belts were attached to the frame the passenger would be entangled with a metal frame as the fiberglass body disappeared around him. The only reason we have seat belts is to keep the kids in place and to hold a car seat in.

Car tires; The cheaper cost of car tires is probably a small consideration when making this change. You could probably buy a lot of motorcycle tires for the price of the conversion. The main advantatge I see is a large increase in contact area, which allows higher cornering loads, harder braking, and less wheel spin when acelerating. When you get down to it, its probably cheaper to drive my 1994 pickup back and forth to work than drive the rig. When driving the rig its the smiles per gallon not the miles per gallon that matter.

Mike

Mike wrote:
>>When driving the rig its the smiles per gallon not the miles per gallon that matter. <<

That my friend should be on a t-shirt !!
Claude

Sahagan,
The clamp on fork braces (tweak bars) allow both forks to work as a unit and help to control the twisting forces encountered when turning. I've found them to be quite helpful in eliminating potential tank slappers in sweeping turns at speed, on rough pavement, in the twisties, or on rain grooved roads.

I've been looking for a fork brace for my mid-glide 41mm front end (Indian Scout).