Rigid Sidecar Combination – Hack
There are many choices to attach a sidecar to a motorcycle. In this article we will be discussing attachment as a Rigid Hack Combination. But before we begin, it is important to explain some terms.
Solo Rider: Riding a motorcycle without a sidecar attached.
Counter Steering: The method of leaning a motorcycle, that a solo rider uses to steer the motorcycle into corners and bends.
Outfit: A sidecar.
Rig: A motorcycle.
Hack Combination: An outfit rigidly connected to a rig. “Neither Motorcycle nor Sidecar lean”.
Double Combination: Two sidecars are attached, one on each side of a motorcycle. “Neither Motorcycle nor Sidecar lean”.
Leaner Combination: An outfit connected to a rig that allows the rider to counter steer as the motorcycle leans while turning, meanwhile the sidecar occupant and boat remain upright. “Motorcycle leans and the sidecar doesn’t.”
Flexible Combination: An outfit connected to a rig that allows the rider to counter steer as the motorcycle leans while turning, with the sidecar occupant and boat leaning in the same direction as the rider. “Motorcycle and sidecar both lean”.
Parallelogram Combination: An outfit connected to a rig that allows the rider to counter steer while turning, with the sidecar boat and occupant remaining upright, while the sidecar wheel will lean in the same direction as the rider. “Motorcycle and sidecar wheel lean and the passenger doesn’t”.
Chair Driven: Outfit is driven from a wheelchair in the sidecar. “Usually attached as a Hack and driven by a wheelchair occupant”.
Tow In Adjustment: Adjusting the outfit wheel to angle slightly toward the front of the rig. Necessary for all four combinations.
Lean Out Adjustment: Adjusting the outfit to lean out vertically, slightly away from the rig, enabling it to straighten when the weight of a passenger is added. Necessary for a hack only.
Wheel Lead Adjustment: The centre hub of the outfit wheel is located forward of the central hub of the rig’s rear wheel. Necessary for all four combinations.
Flying the Chair: Driving a hack with the outfit lifted off the ground. Hack Combination only.
Leading Link: A modification to the motorcycle’s front forks. Telescopic forks were designed by manufacturers to enable the solo rider to lean into and out of corners and for the motorcycle to self-centre. When a sidecar is fitted to the motorcycle, the rider can no longer counter steer and therefore is now required to drive, instead of ride the hack. This requires much more effort from the driver. When Leading Link is used to replace the telescopic forks, the trail is reduced, which reduces the effort required to steer the hack. This modification is necessary for a hack only.
Steering Damper: A steering damper is connected to the front of the motorcycle to prevent steering wobble. Necessary for a hack only.
Time to Watch a Video
Now that we understand the various methods to attach a sidecar to a motorcycle, lets “Chill Out for a Minute” and look at some “Nice Sidecars” at a Sidecar Rally:
As you just saw in the video, Rigid Sidecars may not LEAN, but they come in many varieties and can be attached to many types of motorbike.
Image: Wheelchair Accessible Sidecar Hack, (my daughter and I).
Attachment: The measurements indicated are to be used as starting points from which finer adjustments can subsequently be made.
The following information and images from the American method of attachment has been modified to Australian, wherein the sidecar is attached to the left-hand side of the motorcycle.
Attachment points indicated on four basic frames. X marks indicate alternate attachment points.
Toe-in, Wheel Lead Vertical Lean and Steering Damper Explanations
In the diagram below you will notice the distance between the motorcycle front wheel and a piece of straight timber inline with the sidecar wheel (C). You will also notice the distance between the motorcycle rear wheel and the timber (D). When Toe-in is adjusted, the measurement of (C) is less that the measurement of (D). Therefore, the front of the sidecar is “Toeing-in” toward the motorcycle front wheel. Correct Tow-in adjustment is important to reduce a slight “crabbing” tendency of the motorcycle’s rear wheel, which would cause tyre wear. Incorrect Toe-in will cause handling difficulties as the sidecar will pull to the right or left.
Tow-in and Wheel Lead Diagram
Normal Toe-in is approximately as follows: (C) is less than at (D) by 3/8 to 3/4 inch (9.5-19mm)
To measure this, place a straight edge or straight piece of wood along the edge of the sidecar wheel, and measure from the inside edge of the straight edge to the centreline of the motorcycle wheel rims. Alignment is best accomplished on a smooth level floor.
An incorrectly aligned sidecar will drag the motorcycle to either side, which not only makes the combination difficult to handle, but also causes excessive tyre wear. It is very important to check sidecar alignment at scheduled maintenance intervals and if the motorcycle is difficult to steer.
Image Source: Sidecar.com
Adjust Toe-in by loosening the fastening bolt/nut on the lower rear attachment between the motorcycle and the sidecar frame. This adjustment will also affect the position of the upper rear attachment between the motorcycle and the sidecar frame. Therefore, also loosen this upper mount while adjusting Toe-in and don’t forget to re-adjust lean-out on completion of Toe-in adjustment.
For a more detailed procedure/instructions, download the Year 2000 Ural Repair Manual http://www.sidecarafrica.co.za/Repair Manual.pdf
Sidecar wheel lead refers to the sidecar wheel hub being forward of the motorcycle rear axle. Average Wheel Lead is between 8 to 12 inches (200-300mm). To understand why Wheel Lead is important, imagine a sidecar/motorcycle combination without Wheel Lead, (the sidecar wheel hub is in line with the motorcycle rear axle). This is the same as if you take one of the front wheels off a car. If you turn too fast, or reduce speed suddenly, you will raise the rear wheel off the ground and nose dive the front of the car toward the ground, (on the missing wheel side). This is why Wheel Lead is important.
You can see how dangerous this is, The more Wheel Lead is forward, the better weight distribution, the
further toward the rear, the less scrubbing of tyres on turns. Therefore, Wheel Lead is placed slightly forward of the motorcycle rear wheel to find the best compromise between reducing scrubbing and safety.
Early Harley Davidson rigid hacks did not have wheel lead, whereas racing hacks designed for the track have very large wheel lead.
For best performance with most motorcycles, driver weight, passenger weight and road conditions, the hub of the sidecar wheel should be positioned approximately 8 to 12 inches (200-300mm) forward of the axle of the motorcycle’s rear wheel (B) on diagram below.
This is the standard which is followed by the majority of sidecar builders. There are exceptions, however, such as the Harley-Davidson rig which was set up with the sidecar wheel in line with the motorcycle’s rear wheel.
Vertical Lean is an adjustment using the top brackets between the sidecar and motorcycle to lean the motorcycle itself very slightly away from the sidecar, when the combination is unladen (E) on diagram below.
Normal Vertical Lean is 1/16 to 1/8 inch (1.5 – 3.2mm) at 24 inches (610mm) on a carpenter’s square aligned with the motorcycle’s rear tyre centerline or sidewall unladen and 1/8 inch to 1/4 inch (3.2 – 6.35mm) with a rider on the motorcycle and the rear shocks compressed. Vertical Lean is adjusted by loosening the lock nuts on the upper bracket between the sidecar and motorcycle.
The true test of toe-in and lean-out adjustment is a road test, preferably on a smooth, straight, level, paved road with typical camber slanting off towards the road edge. At a steady speed of 40 mph (60 Km/hr), the motorcycle should not pull to either side while running at normal road speed.
Damper to Prevent Steering Wobble
A steering damper is fitted between the motorcycle frame and the Leading Link to reduce this problem. A great website explaining the causes and cures of steering wobble can be found here.
Attach a Sidecar
A Universal Mounting Kit makes it possible to attach a sidecar to virtually any current motorcycle with a round tube frame, but the motorcycle chosen should be powerful enough to accept the weight of the
sidecar, passenger, and luggage.
Image: Universal Mounting Kit example
Attaching a sidecar should involve these steps
- Attach the frame of the sidecar to the frame of the motorcycle using Universal Mounting Kit Brackets.
- Adjust the Wheel Lead, Toe-in and Lean-out of the motorcycle in relation to the sidecar.
- Connect lights on the sidecar to the motorcycle.
- Connect the brake on the sidecar wheel to the master brake cylinder of the motorcycle.
Now that you know a bit more about connecting and adjusting a sidecar/motorcycle outfit, before you purchase a sidecar and attach it to your motorbike, you will need to know about Leading Link.
Because there is such a big difference between riding solo and driving a sidecar, practice is necessary to develop a good and safe sidecar driver. The word driver is important since one drives a hack (push steering), while one rides a solo motorcycle (counter steering). Before attaching a sidecar to a solo bike, the telescopic forks need to be replaced by a Leading Link.
Hack Project Steps – Connect Outfit to Rig as a Hack
1. Inspect Sidecar Welds. If necessary, re-weld any messy welds on the sidecar chassis.
2. Inflation. Place the rear and front of the motorcycle side of the sidecar on stands to
ensure the sidecar is sitting level. Pump the sidecar tyre to correct pressure. Place 150kgs into the sidecar to confirm correct shocky compression. If after pumping up the shocky, it is not suitable to support this weight, replace the shocky.
3. Locate the Sidecar Wheel Lead. To locate the Lead, place the centre of the sidecar wheel hub 8-12
inches (200-300mm) forward of the motorcycle rear wheel hub.
4. Locate Attachment Points
5. Attach Universal Mounting Kit
6. Adjust Toe In and Lean
7. Install Brakes. If necessary, move the sidecar brake lever to a suitable position, beside the motorcycle gear change lever (Australia), beside the motorcycle foot brake (USA), to allow easy operation. Install the sidecar brake, via a brake line to the motorcycle master cylinder. Test brake operation.
8. Test Ride and Adjust Tow In if necessary. Test ride the Rig (motorcycle) and Outfit (sidecar). Adjust Tow In as required.
Guides and Manuals for Hacks
If you have a motorcycle and would like some knowledge about how sidecars are attached and aligned, I have provided a few links below.
Sidecar Attachment Guides
Sidecar Attachment Guide: ClickHere
Sidecar Fitting Guide: Click Here
Steering Damper Guide: Click Here
Leading Link Explained: Click Here
The Warkshop Guide: Click Here
Manual for Enthusiasts of Riding with a Sidecar: Click Here
Driving a Sidecar Outfit – Step by Step Manual: Click Here
Original Sidecar Manuals: Click Here
Problems with a Rigid Hack Sidecar Combination
- The need to convert the front end to Leading Link and add a Steering Damper (expensive and requires an engineer and modification approval)
- The danger of Flying the chair on a bend will steer you in a straight line until you can return the sidecar to the ground to regain steering control which could collide you with oncoming traffic (You would have to steer toward the oncoming vehicle to lower the chair)
- More effort to steer, I know because I steer my 650kg Rigid Hack (in comparison counter steering is effortless)
- Turning scrubs the sidecar tire (the sidecar tire does not steer)
- Tow-in and Lean-out are required to be adjusted every time the combination is separated and rejoined
The Flexible, Leaner and Parallel Sidecar Provide Solutions
- Effortless Counter Steering
- Sidecar tire steers with the motorbike
- Motorcycle Modification: No Leading Link or Steering Damper modification necessary
- Flying the chair is not possible
- Tow-in and Wheel Lead only needs to be setup once. Lean Out is not necessary
- A Leaner Sidecar can easily be removed and replaced to allow solo riding with minimal adjustments on replacement
As you can see, there are many benefits of creating a Leaner, Flexible or Parallel Sidecar in preference to the standard Rigid Hack. However, if you decide to build a Rigid Hack combination, remember to document your journey, taking photos and writing descriptions that you will be able to help others with their projects as you share on Haul N Ride.
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