Just because you can do something doesn’t mean you should. This caution pertains to issues that might arise when making a bicycle warranty claim or filing a product liability lawsuit should you be injured by a defective bicycle frame or component.
Bicycle weight limits, which I recently wrote about, are an example of what consumers should consider, in terms of liability, when thinking about buying a bike. The topic of bicycle weight limits is poorly understood, leaving consumers to search in vain for the information necessary to make informed bicycle purchase decisions.
In order to write the bicycle weight limit article, I researched the subject and provided specific bicycle weight limit facts from well-known bicycle companies. Having had experience with the warranty claim process, and possessing knowledge about product liability cases, I wanted to present guidelines for how consumers should go about evaluating safe bicycle weight limits.
I thought that I had made this clear, but a commenter came along and made certain assumptions about what published bicycle weight limits really meant (at least in his/her mind). I always appreciate input from readers, and this comment was no exception. The commenter, as a heavier rider, had personal experience dealing with bicycle weight limit issues. Still, this comment made a few points in need of clarification.
The commenter started out with a commonly held belief about riders not having to worry about the weight limit of frames.
“people worry about frames, but that’s not the main concern. frames are pretty study in general. the real problem is rear wheels, which bear the brunt of the weight. A heavy rider may pop spokes on a rear wheel that has few spokes or was poorly adjusted. I had this problem with two different bikes, and upgrading the wheel was the solution. So, if you are worried about “the weight limit for a certain bike” you should be looking at the rear wheel, not the frame. (of course, if you are 400#+, the frame may start to have trouble too)”
Actually, this is a bit misleading. While the commenter is right about wheels being a concern for heavier riders (as I pointed out in my article), it’s not true that consumers shouldn’t worry about frames.
Frames are designed to endure a certain amount of stress. When a cyclist rides a bike, he or she exerts forces on the frame. Over time, these forces cause the frame to fatigue. Each frame has a fatigue strength. When this is exceeded, the frame will fail.
How long it takes for the frame to fail depends upon a number of variables including frame material, design, construction quality, how aggressively the bike is ridden, and the weight of the rider. Stronger and heavier riders will exert more force on a frame than lighter riders.
Bicycles vary as to how many load cycles they can take before they fail. Now, this doesn’t mean that frames will fall apart in a short amount of time either from aggressive riding or the weight of a heavier rider. But frames do have a finite lifespan, so telling riders to worry about the wheels, and not the frames, is unwise. Frames should be inspected regularly for signs of fatigue and manufacturing defects — usually seen in the form of cracks — regardless of the rider’s size.
When talking about weight limits for different types of bikes, I provided information about folding bikes. Bike Friday, a folding bike manufacturer, publishes bicycle weight limit information for their bikes, which I provided in my article.
“Most Bike Fridays are designed with a rider weight limit of 220lbs. The exceptions are the petite models, which are designed for 125lb maximum rider weight, and the Pocket Rocket Pro and Crusoe, which are designed with a 190lb maximum rider weight.
Air bikes are designed for 200lb maximum rider weight. Up to 220 can be supported with heavy rider upgrade.
On special order, we can build bikes with heavy rider upgrades for riders over 220lbs. This does not include the Pocket Rocket Pro or the Crusoe.”
The commenter posted the following in response to my presenting these typical folding bike weight limits:
“please do not generalize to all folding bikes from the Bike Friday specs! I rode a Xootr Swift, which is rated for 260# and I weigh more than that. Now, it doesn’t fold up teensy like a Brompton or BF but you can take it on the subway or commuter rail. (And even BF makes a sturdier version of their bikes for a 260# rider for an extra $100 or so.)”
The commenter compared a larger folding bike with smaller, more typical folding bikes like Bike Friday, Brompton or Dahon. The Xootr Swift is designed to ride like a regular bike, instead of a folding bike. As such, it has regular bicycle geometry, uses standard parts, and is significantly larger than other folding bikes. So, the two can’t really be compared in terms of how much weight they’re able to support.
Consumers should make a point of evaluating such differences when deciding whether to push the limit on a bike rated for 220 lbs. Even with the Xootr Swift’s 260 lb rating, riding it when you weigh much more than 260 lb may not be smart.
Concerning the idea of the inaccuracy of published bicycle weight limits, the commenter made assumptions which may be true, but which constitute bad advice.
“in general, just like maximum PSI ratings, the weight limits published by manufacturers are designed to keep them from getting warranty claims and lawsuits. the bikes are probably good for a bit more weight than they are speced. that said, rear wheels are usually the first to go.”
In practice, bikes may be able to carry more weight than what the manufacturers publish, but the published numbers should not be ignored. Publishing lighter weight limit numbers will not prevent manufacturers from getting warranty claims. The majority of cyclists using their bikes will fall below those limits, so they’re not designed to keep heavy riders from making warranty claims if the bikes fail.
Some manufacturers test the number of load cycles a frame can withstand – or they make estimates on what they think the frame can withstand. Their calculations are based on the size of riders who fall under a certain weight. This doesn’t mean that heavier riders can’t ride the bikes. But, it does mean that the manufacturer isn’t prepared to assume liability for injuries sustained by a rider whose weight is over the specified limit.
This has implications for consumers. All products have a defect rate. Therefore, some percentage of frames will be defective. Savvy consumers will use this information, along with published weight limit information, to protect themselves if they are unfortunate enough to be harmed by a defective frame.
If a rider over the specified weight chooses to disregard the weight limit, he or she will have a difficult time making a product liability claim should the frame fail. It may not be impossible to prove that the frame was defective. But, if the rider exceeds the published weight limit, the manufacturer will argue that his or her weight was a contributing factor in the frame failure. This could reduce the amount of damages the consumer receives for injuries caused by the failed frame.
A prudent way to approach this problem, and to protect oneself in the event of a frame failure, is to abide by the weight limit the manufacturer publicly states as the limit for the frame. Whenever possible, consumers should shop around until they find a bike whose weight limit is close to their weight — a small weight difference shouldn’t matter.
The same principle applies when making other decisions about a frame such as whether to use it in a manner not covered under the warranty. For example, some manufacturers won’t honor the warranty on a frame that is used for racing. Keep this in mind when estimating how long a frame will last; if a frame used for racing fails, the manufacturer won’t replace it and may not be willing to repair it either.
Not to consider these factors is to assume the risk of having little or no recourse when a frame fails prior to a what could reasonably be deemed a normal lifespan. Think carefully before making bicycle weight limit and use decisions — or any decisions about a bike which could reduce a manufacturer’s liability — and choose wisely.