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