SUSPENSION FOR LUIS

Greetings!

I recently had a question from a reader named Luis concerning suspension. I'm going to assume he's referring to rear suspension on motorcycles, and this Old School Chopper project in particular.

The frame I'm going to use will be a rigid frame, referring to the rear section of the frame as it has NO suspension at all. If you can see the photograph clearly, you can see that the frame tubing reaches from the front fork neck to the rear axle plates in a rigid construction and then from the axle plates down under the engine and then curves back up to the neck. I've had a few motorcycles like this, mostly the ones I built myself, and I've had very few problems riding them in relative comfort and confidence. A secret: I don't fill the rear tire completely, it's about half full or less. That minimizes the bounce that can upset your balance. 

There's two ways to have a rigid frame: one is to buy a rear section called a "hardtail" and weld it to your stock frame, and the other is to buy a complete frame that was manufactured as a rigid frame to begin with.

One of the advantages of a hardtail addition for your stock frame is the reduced cost. They can be found new from $200 to $1,700USD. You also need to include the cost of alignment and welding by a certified welder - not cheap.

The disadvantage of a weld-on hardtail is that although the rear of the bike has the look you want, you're going to have to live with the bulky-looking stock neck (and sometimes the motor mounts) with that cast iron look. Builders have sometimes used body filler (bondo) to fill the areas and smooth them out in an attempt to hide the cast look, and it's not a bad idea if you're going to make it a show bike or just want to take more pride in the finished product.

The advantages of a complete rigid frame is that it's usually made by a competent, certified welder in a jig to assure that it's correct and that your engine and other components will bolt in right. Also, the neck area is usually made to give it a bit of stretch outward, away from the engine, and upward, above the engine. 
The disadvantage is that it's expensive, usually from $700 to $2,000USD. Judging by the length of the top motormount in the frame photograph above, I'd guess that this Sportster frame has very little stretch, either up or out. This is a consideration you must make before you buy your frame because is will determine the final shape, or "lines" of your chopper. The amount of stretch you incorporate is a matter of taste and planning. You need a longer front end if you are going to have lots of stretch, but this just may be the look you're going for. On our Old School Chopper, we're not interested in gobs of stretch and we want to use a modest-length front end. But who knows? We may stretch out our next ride, after this one sells.

Other options include the Softtail or swingarm suspensions. Both of these are stock on Harley-Davidsons although the Softtail is only available on the Big Twins. The Softtail has a pair of shock absorbers mounted under the frame and the rear section pivots up and down on hinged mounts below the seat and depresses the shocks for suspension. The swingarm in the photo with the blue fender shows the typical rear suspension for most motorcycles. The swingarm is very comfortable and dependable but it's harder to impress the chicks with your apparent machismo. 

Riding a rigid frame chopper is not as devastating as some men will state. I've found that many of the detractors of the rigid frame are those who have never ridden one. Practically speaking, the bike we're going to sell to someone will most likely be ridden only occasionally - not as a daily transport. It probably won't be raced on cobblestone roads at breakneck speeds. It will probably be ridden on the weekend to a party or through the downtown area while wearing a tight, black T-shirt.

It's not for everybody, it's for that rare, independent-thinking man who has self confidence and courage. That's exactly what chopper riders want others to think, and it's usually what bystanders and wannabes think of chopper riders. The image is exemplified by these heavy dudes at Orange County Choppers. I can personally attest that riding a rigid chopper is a real kick in the pants. You get looks from everyone.

All the dudes want to be you and the women want to be with you. Everybody knows that girls are attracted to the bad boys because they're exciting & unpredictable, and the girls are intrigued by the challenge that bad boys represent and think that they can change them. Women...

I hope this helps Luis!

Doug

ABOUT THAT REPUTATION...

Greetings!

I sure hope I don't upset any hard-core Harley owners with this post. I have a much different perspective of the brand now than I did 30 years ago. It used to be a clear division: Sportster owners/riders and The "Big Twin" owners/riders. As I see it there were a few factors that contributed to the division and made the Sportster the poor cousin to the "74" as it was called. Here's a Shovelhead engine and I think it's totally beautiful.

1. The Big Twin, with the prefix: FL in the serial number sequence, had a higher displacement engine at 1,200cc. The Sportster only had 900cc. :(
2. The Big Twin was used for decades by local police departments in the US and elsewhere, as well as by the US military. Thousands of military veterans and policemen became fans of the Big Twin because it was (is) powerful and exciting.
3. The Big Twin design incorporated a non-unit engine/transmission. The engine bolted into the frame ahead of the transmission, connected by a chain and proper tension was adjusted using a transmission plate that slid forward (closer) or backward in the frame. The non-unit construction required a longer frame, more pieces and more weight.
   
4. The Sportster was, and still is, a unit construction which is lighter and more compact, making for a lighter and visually-smaller motorcycle.
5. The military and police departments in the US didn't use Sportsters for their fleet vehicles, opting instead for the more intimidating Big Twin.
6. A popular folk hero, Evel Knievel** (http://evelknievel.com/), made a name for himself in the '70s by jumping his motorcycle over cars, trucks, busses and even the Snake River Canyon. His exclusive choice of rides: the Harley-Davidson Sportster.
   

Elvis Presley also rode a Sportster (although I'll bet he also owned his share of Big Twins).

But, in spite of Evel's and Elvis' potent charisma, I doubt the Big Twin riders wanted to switch to little Sportsters. The image was that although the "little" Sportster was okay for a rider's first motorcyle, REAL MEN rode the Big Twin. 
Decades ago, motorcycle machinists decided to combine the best of both worlds: The compact size of the Sportster with the larger displacement of the Big Twin. Hybrid engines were produced on a one-off basis.

The crankcases were machined to accept the larger cylinders of the big engine, and although I'm not sure if the crankshaft and flywheels were swapped, the big engine heads looked very unusual on the Sportster cases. When a Panhead cylinders and heads were used the engine was called a Panster, if it was a Shovelhead top end, it was called a Shovster. To me and many others, this configuration was as good as it got. I personally believe the Panster hybrid was the most attractive motorcycle engine ever made. The clean lines of the Pan rocker covers on top made it look expansive and potent and it seemed to blend the two most desirable qualities of the Harley engines into one: Large displacement along with a compact and lightweight overall size. Unfortunately, this modification was extremely expensive to perform so the application was very rare. I never saw a Panster or Shovster in person, so to speak. Only in magazines.
The appeal of this hybrid engine lets us make a couple of assumptions: 

1. If the larger, more powerful engine was produced in a smaller package it would satisfy the majority of riders,and
2. if so, why would Harley-Davidson produce an engine that is less than 1,200cc in displacement?

So, there is my justification for using the Sportster for my Old School Chopper Project. I've personally owned over 20 Harley-Davidson motorcycles, 90% of them have been Big Twins, but I'm not at nearly as interested in building a chopper from the larger platform.

True, they look stunning when done right, but I think I can make a Sportster look just as stunning for less money and with less weight and fewer parts. 

There's only one drawback to using the Sportster for this international project and that is the money they bring on sale day. The Big Twin sells for more money than the Sportster -period. Unfortunately, although a Sportster costs less to buy, many of the parts used for a Sportster chopper cost the same as they would for a Big Twin chopper. We're keeping a close accounting of expenses on this project so we'll be able to report just what our investment was. 

Hey! I just thought of something: if we disclose our expenses in this blog and then offer the completed bike for sale, the wise buyer would have access to this blog (and we want him to) and see just how much money was invested. I hope this full disclosure blog turns out to be a good idea. 

**A postscript about Evel Knievel. He worked for a time in the small Washington State town of Sunnyside, on the east of the Cascade mountains. It's the town where my wife was born and went to school. It's been said that he worked for Don Pomeroy selling motorcycles and that Don taught him how to ride standing up on the seat and how to do a wheelie (riding on the rear wheel only). The building that was the motorcycle store where he worked at that time is now owned by my wife and I (Where Evel worked). It is for sale at the time of this writing. You could own the building yourself if you email me and send me a check for $500K. I'll be standing outside by the mailbox.

Doug