John’s Leaner Sidecar Combination – Homemade Project

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket


Bike Make/Model

2011 Triumph Rocket

Make/Model and Details of Sidecar Tub – Fibreglass, Aluminum (aluminium) Wrapped, Steel Sheet Wrapped etc

1975 Spirit Eagle Fibreglass Side Car

Sidecar Tub Design – Tandem/Single

Single Passenger

Sidecar Frame Type and Measurements – (Square/Round Tubing, Aluminium/Steel)

Round Steel Tubing


1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket


Tow in/out Measurements

Toe in-out measurements are all the same both loaded and unloaded. I strapped a pipe to the outside of the side car wheel and then measured from the bike wheel (held upright) to the center of the pipe. In all cases I got 56-1/2″ at the front and 56″ at the rear… considering error, that’s about perfectly aligned. A fuzz toe-out should be more stable, and this rig is indeed (90mph on the highway with ease and solid).


Rear Mount Ground Clearance Measurement

Height of the rear pivot off the ground is 3-1/2″


Front Mount Ground Clearance Measurement

Height of the front pivot off the ground is 7″


Motorcycle Sub-chassis Details (Square/Round Steel Tubing, Aluminum etc) and Attachment to Motorcycle (High Tensile steel, lock nuts etc)

Custom Sub-chassis


1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket


Distance between pivots

Distance between pivots is 22-1/2″


Total Width of Combination

The CL-CL measurement of the cab of the car to the CL of the bike is 37″
the Overall width of the rig upright is 72″


Total Width of Combination Lean-out

The max width of the rig leaned over to the left is 86″…. that’s a hard measurement.


Distance Between Sidecar and Bike

The amount I extended the side car frame away from the bike, measured to the CL of the pivot is 17-1/2″.


Sidecar Tire (tyre) Speed, Weight Rating


Sidecar Rim Details, Diameter, Rim Width etc


Suspension Type (Shock Absorber/Swing arm/Torsion) on Sidecar Wheel

Swing Arm Coilover Spring Shock Absorber


1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket


Pivot Attachment to Motorcycle, (Rose Bush, Heim Joint, Rod End etc)

Heim Joint Rod Ends


Sidecar Brake Details (if fitted), Drum/Disc, Plumbed to Motorcycle Rear or Front Brake Cylinder


Modifications/Adjustments During the Build


Photos of the End Product


1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

I wonder who is enjoying the ride more?


1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

1975 Spirit Eagle Leaner Side Car with 2011 Triumph Rocket

What an amazing build.

Most leaners have the pivot mounts on the bikes centreline, your’s however appears to be off set toward the sidecar.

Perhaps you could write something for your page, to explain why you chose this, how it rides, whether this causes issues or performs well.

Anyway, amazing job and I can’t wait for some measurements, tube size, extra details etc. Have an amazing day. Dave


Hi Dave, yes I figured the non central line installation would raise an eyebrow.

But, from an engineering standpoint, if you follow the force vectors that apply from the sidecar to the motorcycle, the slight offset is relatively insignificant.

The majority of load is a huge moment/twist that pushes the rear tire to the left and pulls the front wheel to the right. That would be true for any sidecar. The real issue is the amount of lean that the Pivot Point has, so the lower the pivot points are to the ground, the better. I offset the front pivot mount further outboard than the rear pivot mount.

I don’t think that is a significant issue, though it does tend, theoretically, to toe in as the sidecar moves up and down over bumps, independent of the bike. I found no problems driving it.

I think the bigger concern is the frame and the attachment points, and whether the frame can handle the load. So it is more important to find the best way to transfer the load to the frame in the bike then it is to worry about getting in the Centerline of the bike.

Again remember the primary load is the big dead weight hanging off the right hand side of the bike: doesn’t matter where you attach it, the force vectors are the same. So I’ll be happy to draw up some diagrams about what I did.

I think the biggest issue I’m having with this ride is that the sidecar is designed for a much smaller bike and in order for me to connect it, I had to have the sidecar wheel further in front of the rear wheel than is optimal. That translates to more  side load on the front wheel, especially when going slow with a load. I bet I could not resolve the geometry on the frame without significant modifications, which I did not want to do. But that is what you get with a 40 year old sidecar.

I know that’s a lot of explanation and I’ll be happy to type it up in a more cohesive fashion later. Thought you would like to hear my ramblings.

Also, really cool project page! Thank you so much. John


Update: In response to a question in the comments below, John has requested I insert his reply here (due to the length of the reply). I will paste it exactly as I received it.

Response to the question about how to make the mounting bracket for a “leaner” sidecar mount on a Triumph rocket:

To the question about exact measurements for the bracket, I’ll try to get measurements when I get back to Vegas…. The bike has been buried in the garage because of the Vegas heat (117). But, I’d say that the system is custom made and takes some in-place welding to fabricate…. If you’re not a welder, you’ll need to find someone who can do custom work and will work with you… find someone welding out of their garage… there are lots of them out there.

I decided to mount the Heim joints to tabs welded to the case guard since that is a robust piece attached to the frame/engine both front and back.. therefore the loads from the side car travel to proper stress points… plus, the case guard is low on the bike and made for decent leaner mounts.

Here’s a picture of the case guard with the tabs welded to it…. The tabs are 3/16” steel plate custom formed. It is important that the bottom edge be straight and level with the bar so that the tabs become the baseline for the rest of the build. In this picture is the front tab for the front heim joint (has the big hole in it), which will connect to the tab in future pictures.

Motorcycle Leaner Sidecar Triumph Rocket

Motorcycle Leaner Sidecar Triumph Rocket

Here are several pictures of the finished product. Carefully look over all the reinforcing I did and how I brought the load to the bolts… what needs to be accounted for is the very large side loads on the mounts, therefore the mounts must be braced both linearly, and perpendicularly… I tied the front mounting tab and the rear mounting tab with a large steel bar (it’s actually a steel concrete form stake I got from Home Depot.. actually the two plates with the 5/8” holes in them for the Heim joints are concrete anchor bolt plates from home depot, they are raw and come with 5/8” holes in them already.. perfect for welding).

Note I had to add spacers to move the heim joints away from the plates a bit… those are just tacked on in a couple spots. They are held by the bolt holding the heim joint.

Motorcycle Leaner Sidecar Triumph Rocket


Motorcycle Leaner Sidecar Triumph Rocket


Motorcycle Leaner Sidecar Triumph Rocket

Motorcycle Leaner Sidecar Triumph Rocket


Finally, I braced the rear mount to the opposite side of the bike frame with this bracket here (which I welded in-place to get it exactly right).


Motorcycle Leaner Sidecar Triumph Rocket

In the following picture you can see this support bracket coming out the back.

Motorcycle Leaner Sidecar Triumph Rocket


Thank you so much John for sharing such detailed information in reply to Keswani’s questions. You Rock! 🙂


Took the boy out for a long ride today (he’s 21)… super smooth, he was very comfortable.

One could easily tour with this rig, though in town, at slow speeds and a load in the car, it’s a handful…much better at speed… but that’s nothing new.

Thanks again!


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Thank you for visiting Haul N Ride. Dave

10 thoughts on “John’s Leaner Sidecar Combination – Homemade Project

  1. Chuck Wubenhorst says:

    I am SO GLAD to discover your Post . I’ve been trying to Convince myself that a side mount would work for the Leaning of my Yamaha Roadstar . I know there will be some Trial & Error involved , but I now have the confidence that it is doable . Any input on your part will be very welcome . I’m a bit puzzled as to the location of the outer wheel forward of the Bike rear wheel and it’s angle to the line of the Bike .

    • admin says:

      Hi, a great website for ideas is Kalich Leaner:
      You ask very good questions regarding the location of the Sidecar centre hub in relation to the motorcycle rear axle.

      It makes sense that the same forces exist on a Leaner Combination as a Rigid Hack Combination.
      Wheel Lead (sidecar hub slightly forward of motorcycle rear axle) would stabilise the combination (imagine a car with a missing front wheel).
      Also that Toe-in would be necessary to prevent scrubbing of the tires and assist in steering.

      Obviously Wheel Lead is decided during design and build and is difficult to alter after completion.

      Toe-in could be adjusted after the combination is complete if you allow for that adjustment.
      However, the front mount (in front of the engine) is slightly higher than the rear mount (lower frame) which naturally steers the sidecar to prevent scrubbing of the sidecar tire.
      So theoretically, the ability to lean while travelling straight should auto correct Toe-in/Toe-out issue.

      Although not a leaner, a great example of Wheel Lead is here:

      Good luck with your project.
      Feel free to share your build with Haul N Ride

  2. John Harris says:

    Did a 500 mile ride with the rig a couple days ago and the dog (one day ride though the dog got a break from riding for 250 of it when he was in the truck with my wife). Dog did great and was quite jealous when I left without him! He would bark and bark when he saw me so I had to ride behind my wife. Either he loves his pop, or he loves to ride! The rig rode beautifully… on the big slab I was doing 80mph easily with traffic and on the back roads I was doing 65-70 again no difficulty. It all rides just like a normal bike… except with my doggie..

    The whole rig does take more gas. Before side car I was getting about 31-32MPG in the Rocket. After I am getting 26-27. Oh well, drag is drag.

    • admin says:

      Great to hear from you John. It sounds like you have ironed out any faults with your setup and it is performing well. May I ask why you said, “It all rides just like a normal bike… except with my doggie”.
      Could this be due to weight shift, as he is not seated and moving around, or could it be due to just the extra weight?
      I ask this because previously you had said, “Took the boy out for a long ride today (he’s 21)… super smooth, he was very comfortable.”
      You have got me curious. Dave

    • Liz Wright says:

      Omg I want to do this so badly. Do you think I could make this work on a wee Strom 650? I have a triumph Street twin but I want to put the sidecar on the Suzuki. Thoughts?

  3. Keswani says:

    Hi. Can we have some exact measurements please ? I also have a Rocket and want to build a Sidecar so it would be lovely to have some ideas.

    • John says:

      Hi, Keswani.

      Dave posted my reply to this question in the body of the article above. I’ll get measurements when I un-bury the bike though copying exactly isn’t critical, just properly reinforce the system loads. Heck, hopefully you’ll improve upon it!


      • admin says:

        Thank you John for offering your assistance to Keswani. I look forward to adding measurements into the article above. Cheers Dave

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