Is road bike weight limit determined by frame or rim and tires?
 

As the title. Did vintage road bikes have a weight limit back in the day? If so, does the weight limit apply to the frame or rim/tire combination? Either one, where would you find such a spec? @ my 230lbs. just curious. Also in reference to tires, I've heard tire size 20A tossed around.. Is 20A a tire size or something else?

All of fhe above can make a contribute

Pretty simple 32 spoke wheels will handle 230 lbs. I have been as high as 280 (225 now) and never had a problem with a good quality lugged steel frame and 32 spoke wheels

The Deacon's One Hoss Shay:

https://www.gutenberg.org/files/4528...-h/45280-h.htm

Somewhere out there, someone has preserved a mid-1980's spec sheet from Columbus that specified the weight limits for their various tube sets (steel, of course). The only one I remember is their SL set, with a weight limit equivalent to about 180 lbs. I believe there was a size limit, too, with a recommendation that larger frames (58 cm and up?) be built with SP tubes rather than SL.

Seems low now, but almost of the people buying racing frames in those days were fit racers, probably averaging somewhat under 160 lbs. Even tall American racers tended to be slender enough to stay under the SL weight limit.

I would say that rider skill and style has a lot to do with the weight limit for a particular bike or wheelset

are you skilled at dodging potholes ? Do you unweight over bumps ?

if the tubing says "limit 240 lb" and you weigh 239 does that mean it's OK ?

things to consider.

/markp

Who doesn't unweight going over bumps? Simple arse preservation would make this instinctive, I would've thought...:foo:

The heavier the bike, the more it will carry. LOL Any SS or IGH can carry 350 lbs likely. They carry a passenger in Holland.
There was a size EA3 that is 590 mm. 1/4" more than a 650B/ 584. I switched one bike between these.
My custom tour bike with Rohloff14 laughs at 290 lbs.

The bicycle is still carrying the same amount of weight irrespective of where your rear happens to be at a specific moment.

Especially considering that Trek, for example, says this for every mountain bike model they make

Carbon or aluminum, doesn’t matter. Somethin’ smells fishy here.

I think weight limits and the norms and standards necessary to have meaningful and comparable numbers is a fairly recent thing. I don't know how "vintage" you are talking about, but I seriously doubt that even if there was a weight limit given for a road bike from the 70s, that it would "mean" much. Without some certainty about how that number was arrived at, they don't mean much. Just the difference between a stationary and dynamic loading alone is critical.

I wan't commenting on the weight on the bike per se, just the impact on your arse. However, to address your comment, lifting one's arse converts your body weight from deadweight to sprung weight which is way easier on the bike. The weight on the bike doesn't change, but how the bike is allowed to move under that weight makes all the difference.

Yes, I've seen frames destroyed because of this issue, particularly when the bike is on the small side and the seat is at max extension.

Fortunately, my bike has a frangible link that breaks before the weight exceeds the machine's maximum load; me! Well before I get to a load that will break the bike, the load will break me, and I'll be lying there like an inverted turtle waiting desperately for help to get rightsideup again.

I have no clue about the answer to the original question. However, the premise of the question seems a little bit odd. I think that the frame/rims/tires should all support approximately the same weight. If one of those supports more weight than the others, then that component is overbuilt for the application.

Every item on a bike that is loaded has it's own limits. My current mountain bike's frame is quite strong, probably wouldn't have any issues with a 200LB+ rider, but the wheels on the bike have a much lower weight limit. On the other end I had a road bike with really strong wheels but the frame was very light/flexible. My current road bike has a stiff frame and strong wheels but very light/flexible bars/stem so that is the weakest point
In the vintage era some items like SL tubing had semi official weight limits, but generally speaking there wasn't single big database of weight limits. Shops and riders with experience would often be holders of that knowledge just from what they had experience with worked with, broken. Most of my experience with that shop/rider knowledge had three levels: safe weight, it's light and flexy weight, and you will brake it weight. Depending on how you were riding you would make sacrifices in the weight. For touring you don't have room for failure, but for racing the weight advantage might be a risk you are willing to take (the reason you see all the vintage era drillium bikes for example)

I would say both, particularly if you're talking about high performance "racing" stuff.
"You can have Strong, Light, or Cheap; Pick two" as the saying goes, but there's a point where minimizing weight will compromise absolute strength, regardless of cost.

Based on anecdotal evidence from here, and the cycling community at large; I'd say that entry level to mid range bikes tend to have lower quality wheels, and less optimized frames (overbuilt) so you see more wheel failures.

A higher end, high performance bike generally gets stronger, stiffer wheels, but that usually goes together with a lighter, more weight -optimized frame with less "reserve capacity" than a more budget bike. Couple that with the more strenuous use that the rider of such a bike is more likely to engage in and you're more likely to encounter frame damage, ironically, than an inexpensive bike (though pretty rare)

That's equivalent to "You can have cake, pie, or ice cream; pick two!" The choice is usually presented as "Strong, light, cheap; pick two."

Put another way, beginners break wheels. Experts crack their frames. Interesting stuff.

Unless you're bunnyhopping.

Bunnies pay the price for temporary levitation time in increased force with which they hit the ground when landing - ;)

Even a less than high end wheel can do much better if they are maintained - periodic check to ensure that they are true and have even tension on spokes. Beginners usually do not check or adjust things for a variety of reasons, including not having confidence in their ability to do it correctly on their own. [I am thinking of one of my nieces.]

It's gentler than the expansion joints I'm hopping!

To put it this way; a super light carbon racing frame is still plenty strong, but it doesn’t have the “reserve capacity” of a less expensive alloy “sport” bike. You’re also more likely to be subjecting a race bike to more high performance, high stress use; you would be more likely to do something that would damage the frame, not that it actually happens more often

In practice though, with regards to the OP, it’s usually the wheels that are the weakest link; especially for less expensive bikes and heavier or less mechanically sympathetic riders.

Um, no.