Wide Tire Bikes
Before we get into the technicalities of the typical wide-tire frame it is important to understand that bikes built around wide rear tires have distinctly different handling characteristics than cycles using more conventional rubber. Some people say that wide-tired choppers handle poorly and this is a true statement up to a point but I prefer to say that a well-designed fat tire bike handles 'differently'. Notice that I said 'well designed'.
Despite what we see in the popular chopper rags fat-tired choppers represent a very small minority of all the chopped bikes on the road today. If you attend many shows, rallies, swap meets and other events you'll no doubt notice that for every wide-tired bike there will be at least fifty 'conventional' bikes and this 50 to 1 ratio is substantiated by the feedback we've been getting from our clients and site visitors. In fact the vast majority of our customers and friends are building bikes that use 200mm or under rear tires by about a 100 to 1 ratio. At the last really big bike event I attended I only saw five wide-tired bikes parked in the streets along with around three thousand or so other rides but the show floor was full of fat tire scooter displays.
It all comes down to 'appearance' over 'practicality'. Good looks and good handling don't always follow the same path but somewhere along the line you can reach a good compromise if you pay attention to details and don't get swayed by the latest fads or trends in show bikes.
In my opinion, and it is only my opinion, the maximum size rear tire that can be used on a chopper designed for 'serious' all-purpose road-work falls somewhere between a 180 to a 230mm with a 200 or course being the ideal candidate. An experienced rider won't notice much difference in the handling characteristics of a 200 compared to a 150 and depending upon the overall chassis design a bike equipped with such a tire can handle the twisty roads, traffic congestion and tight urban parking lot topography as well as most stockers or road racers. If the rider however is willing to modify their own behavior and to make some compromises in their riding style then they may be happier with a wider tire if they are going after some kind of 'look' that they simply aren't willing to give up.
You can't dismiss the pursuit of appearance entirely. I have personally owned some bikes that handled miserably but they looked really good so I just adjusted my riding habits to suit the ride in question but I would not have ridden any of these bikes cross country as I personally prefer a very responsive cycle, that I ride, and not a cycle that rides me, if you know what I mean.
For those who don't understand what I'm talking about I've included an excerpt from a rode test article in one of the Chopper magazines where the writer is talking about the handling characteristics of a pretty popular 250-tired softail bike:
"The fat rear tire causes a slight constant pull to the left due to the engine and transmission offset but nothing that changing your riding position can't overcome. The overall handling of the bike is fine but there is a limit to the lean angles and sometimes the bike feels a little unstable with sudden lurches in corners. On many occasions I found myself scraping the lower frame rails and on left-handers grinding the primary cover or kickstand. The six over forks combined with the wide rear tire make it a little inconvenient to maneuver in tight traffic and winding roads caused us to slow significantly. A better suspension system would help tremendously as the frame bottoms out even over slight road irregularities due to the increased weight of the tire and swing-arm. This bike is probably best suited for straightaway highway cruising".
In another article, this time written for a road test of a fat rigid frame the rider wrote:
"The process of getting familiarized was a combination of fighting it and becoming its best friend. At first I had to muscle it into submission just to keep it on the road. The bike is a little cumbersome and clumsy at low speeds. It takes concentrated steering effort and not just normal body-english to get it into sweeping turns but once into the corner the bike remains on its line relatively well".
I've been around a long time and in my opinion these articles were using 'sales-speak' for "This bike is piece of crap and should be used for 'show' purposes only". The writers were basically telling us laymen how to enjoy eating a tough steak when they should have been telling us how to find a good steak to begin with but when you have to answer to your advertisers you have to compromise your ethics just a little bit.
Most of the folks I know who have built fat-tired rides have enjoyed them for what they are and that's a show piece or bar-hopper but I don't know anybody who'd build another one which says a lot about their usefulness. It's great to have one in the garage to show people but it's a whole lot better if you also have a serious 'rider' parked next to it.
Fat tired bikes require the builder to do far more design planning than more conventional cycles as there are simply more variables involved. First and foremost is the selection of the tire itself as there can be considerable variation in the actual tire dimensions from one manufacturer to the next. Then comes the selection of the wheel, which also has some bearing on how wide the mounted tire will be at the widest point in the sidewall. Once the wheel and tire have been selected it's up to the builder to decide whether they want to go with a chain or belt final drive and what size chain or belt to use. Most 'experts' won't endorse the use of belts with wide rubber but the vast majority of folks still insist on running a belt anyway. The selection of the drive system has a tremendous impact on the design width of the rear wishbones and lower rails and the minimum to maximum clearance can vary by as much as one inch on the drive side rails.
Once you decide on the drive system you'll have to find out if you can buy an offset kit that will accommodate the components you've selected up to this point or whether you'll have to have something custom made. In the mix you'll also have to consider whether or not you want to opt for a right side drive transmission so you won't have to offset the motor and tranny.
If you find that you can buy all of the components you'll need you must also be prepared to either look into a hotter power plant or be willing to ride in the rear of the pack since the average fatty weighs anywhere between a eighty and a hundred and fifty pounds more than a conventional bike.
Before you start building a wide tired bike you must be prepared for some of these compromises you may have to make and you must also be prepared for the additional expenses such bikes demand and these expenses are considerable compared to a more conventional chopper. If you're willing to make such concessions and you have the money we'll not waste any more time and get right into it in the next section.
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