Tom’s Sunbeam Leaner Sidecar Project – Haul N Ride


Bike Make/Model

1950 Sunbeam

Headed by John Marston, Sunbeam experimented with motorised versions of the bicycles and in 1912 released their first motorcycle.

Marketed as the “Gentleman’s Machine”, Sunbeam became part of the Associated Motor Cycles Ltd in 1937.


Sunbeam Leaner Sidecar Motorcycle

Sold to the BSA Group in 1943, production moved to Redditch, Worcestershire and built the S range from 1946 to 1956, one of the more unusual motorcycles offered in the period.

Designed by Erling Poppe and the first completely new post-war motorcycle, featured an in-line 500cc twin cylinder with shaft drive, available as the S7, an improved S7 Deluxe and sporting S8.

The S7 Deluxe, introduced in May 1949, benefited from improvements to the forks for better handling while the S8 was a lighter, less well appointed model that did away with the fatter wheels and tyres that were a feature of the S7.

Virtually hand built to the highest standards, the Sunbeams lasted until 1956 before production ceased altogether.

Today, these legendary bikes hold a special place in motorcycling history and remain highly collectable.


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

Undecided at this stage.

“I’ve been playing with these for a while on and off have been trying to get a unison leaner to work on a 1950 sunbeam.

I think the sunbeam has lots of limitations on the pivot points so I’m considering building a sidewinder type.


Sidecar Tub Design – Tandem/Single


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

Adapted Watsonian Meteor – Angle Iron and Round Steel Tubing

Motorcycle Leaner Sidecar Project

Motorcycle Leaner Sidecar Project

Motorcycle Leaner Sidecar Project

Front/Rear Mount Measurements

Just wondering what the height difference between the front and rear pivot points should be?

I have chosen a 3″ difference between the Front Pivot Mount and the Rear Pivot Mount.

I can see the plus points of this type as opposed to the unison setup’ ie simpler and lighter, lightness being the thing I,m looking for as the bike only has 23 hp and brakes to match.” Tom


Thank you Edwards for providing Armec Sidewinder Front and Rear Pivot Mount measurements for Tom.

Rear Mount Ground Clearance Measurement

Front Mount Ground Clearance Measurement

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

Total Width of Combination Lean-in

Total Width of Combination Lean-out

Distance Between Sidecar and Bike

Sidecar Tire (tyre) Speed, Weight Rating

Sidecar Rim Details, Diameter, Rim Width etc

19″ wheel from a 1930’s BSA sidecar frame. Currently addressing ground clearance issues.

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

Dave – I am wondering, Tom, how you will put a passenger in the boat if there is no shock absorber on the sidecar wheel? Is it a torsion shocky?

Tom – Yes my son is going in the tub, the tyre will be run at about 10 – 15 psi to give some cushioning, the bike only has 1/2″ of springing at the back anyway.

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

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

Motorcycle Leaner Sidecar Under Construction


Tom – “I can get about 45 degree lean, which on a Sunbeam is quite daring, even whilst riding solo. Trying to keep the weight under 50kg finished.”


Dave – Thank you Tom for sharing with Haul N Ride.

Please keep us up to date with your progress.

Ride safe, Dave


Share Your Project

Submit Your Leaner Sidecar Project: Write a comment below indicating you would like to share your story and photos of your build. Other motorcyclists would love to see your project. 🙂

Haul N Ride website was created to explore Innovation and Human Creativity with a focus on Interesting, Rare and Unusual Motorcycles and Accessories. Haul N Ride welcomes the sharing of projects and ideas, creating an enjoyable and educational online resource. We like to hear from readers so please leave a comment below and let us know if this post helped you or if you have any questions.

Thank you for visiting Haul N Ride. Dave

2 thoughts on “Tom’s Sunbeam Leaner Sidecar Project – Haul N Ride

  1. Christian Orman says:

    You have a GR-8 website. I check back regularly for anything pretaining to my upcoming project.
    As previously mentioned, I found a Vetter Terraplane in Michigan, its being shipped to Spokane, Washington where I will attempt to mate it to my 2014 Moto Guzzi 1400 California Custom as a “Leaner”. I’ll send photos of the progress, if you like. This may be the only Guzzi powered, leaning Vetter Terraplane in captivity,
    If anyone has any advice, I thank you in advance, should be fun,
    Christian Orman

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