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-   -   How much weight can a bicycle handle? (http://www.bikeforums.net/general-cycling-discussion/27999-how-much-weight-can-bicycle-handle.html)

chip 05-24-03 06:49 PM

How much weight can a bicycle handle?
 
They say a bicycle is suppose to carry ten times it's weight...some bicycles can be heavy so I dare say if you can handle the bike then it can handle you...actually I made that up I never heard anyone say that before?...but it is my guess anyway.:(

Kev 05-24-03 06:56 PM

Well I pull my son on a tag-a-long type bicycle and he weighs 70lbs plus around 15 for the bike, it has a wheel so takes part of the load but he gets off balance sometimes and really pulls me one weigh or the other. There are riders who are trying to lose weight who weigh over 250 lbs who ride road bikes and there bikes are probably around 20lbs give or take.

Inkwolf 05-24-03 06:58 PM

I'm sure that the bicycle makers have a specified weight capacity for each model. I don't think you can make any generalization based on bike weight or size...

chip 05-24-03 07:02 PM

I do not think you can count pull along weight...I know there will be some additional weight pulling your son but will it be the full 70 lbs.?I do not think so.

chip 05-24-03 07:05 PM

They never tell you how much weight you can have on a bicycle...I never have seen it when you buy a new bicycle from the box I never recall seeing a weight restriction

horndude 05-24-03 07:10 PM

Dunno for sure but Im guessing something like a SS mtb with decent wheels prob could handle around 400lbs or so....may have to go with trad geometry though or seatpost would prob be first thing to snap.Ive done 4ft drops off loading docks on mine and I weigh 145......I havent bent anything yet from that height,dunno how much force that puts on the bike,but Im sure its several hundred pounds.

Kev 05-24-03 07:27 PM

1 Attachment(s)
Well David Michael Anthony pulls up to 1,700 pounds with his bike.

cyclezealot 05-24-03 07:57 PM

Kev... I cycled by this Micael Anthony going through Temecula when he was almost home. He had a couple bikes on his trailer, as I recall. . He was preoccupied when I passed him by.. He said his mtn bike had another cracked frame., and was changing out bikes, again....

Kev 05-24-03 08:02 PM

Even to pull that much weight for 100ft says alot for a bike frame, can't exepct it to last forever under that kind of load. On his web site he lists everything he has broken :)

cyclezealot 05-24-03 08:10 PM

On my central coast tour, I carried about 50 pounds. I did not like the way of bike feels with that much weight. Felt really tipsy. did fairly well at climbing. I was surprised, since I had done little previous riding with weight.
I always suspected the most vunerable part of the bike under weight is wheels ...Particularily the spokes.. When my LBS found out my touring bike had lots of spokes breaking( luckily prior to my tour) my great bike wrench upgraded my spokes at a great deal. Was good of him to do that, because normally his policy is, is just to swap out for new wheels.

Inoplanetyanin 05-24-03 10:09 PM

Simply!
Bikes that are designed for kids, will be safe with load around slighly more than average weight of a kid.
Adult bikes WILL carry the weight of 99% of adults. I.E. - 260+ lbs, PLUS THE GEAR.
As my own experince suggests, frame is capable af handling as much as you can put on it so that the bicycle can still roll. Was using teenagers bike for carrying heavy steal beams of about 50-60kgs each.
It's not the frame, but wheels and tires that might fail first.

The axle can be bent on the bump and rarely a fork can fail. Again, if it's WAY overloaded and happen to hit a bump.

No reasons to worry.

http://cyclelogicpress.virtualave.ne...59AafsLoad.jpg

shokhead 05-25-03 05:55 AM

Pulling weight will be different then riding weight.

FOG 05-25-03 08:11 AM

I think the question ought to be broken down:

How much weight can the frame take: The frame is supposed to be a non moving part, so the answer is likely to be quite a bit, unless you go for an unusually light bike, or a poorly made bike with pretensions of being light. The failures in a frame are likeliest at a poorly welded/brazed/epoxied joint. It is not all that relevant how much weight the frame bears if it is well made or stout. Another frame issue is how much shock gets transmitted to the frame by the wheels. Here the tires and suspension, as well as wheels o\and fork come into play. If those components are too stiff, then you could have a problem.

The next component to consider is the fork. Most forks are stout enough, but again some are too light for the materials used. they could break. A couple of serious issus with forks include shimmy, which might be more related to too stiff a fork, at higher speeds), or wobble, from a fork not stiff enough for the load at any speed.

The next component is the wheel itself. I am looking for more info on wheels for heavier riders (like myself) on another thread. One problem here is if the rim flexes, the spokes can become loose. there are lines of thought regarding heavier duty wheels on both Shedon Brown's website, and Peter White's website. I think this is the most critical element in a bike for weight bearing.

Last, we come to the tire. If the tire is properly inflated it can absorb most reasonable weight, at least until you get to near-exotic dimensions, like 700x18c. The interesting thing about tires, is although larger width tires have more inertia, they have minimally greater rolling resistance (at least according to studies discussed in various websites and threads), yet can contribute to the effective strength of the bike by absorbing some shocks. Further, a tire that is not as highly inflated will not be forced off the surface by the minor imperfections in the road as easily. A 700x28 or 32 won't seem much more difficult to ride at 85 psi than a 700 x 20 at 125, yet will do more to reduce stress transmitted to the frame.

bottom line- be cautious on forks and wheels and mount appropriate tires

MichaelW 05-25-03 09:11 AM

Have you ever seen pictures of guys in China and India, taking their bikes t
o market. They are loaded 10ft high with agricultural produce. These are heavyweight bikes made from the crappiest grade of steel.

Inoplanetyanin 05-25-03 07:49 PM

That's exactly my point.
Worrying about weight carrying capacity sounds like a made up problem.

Pat 05-26-03 03:58 AM

I do not know what the limits are on bicycle carrying capacity. We had a guy in our club who was nearly 300lbs and 6'8". I have a friend who got up to 320 lbs and decided to bicycle for exercise and lost 100 lbs.

Bicycles tend to be overengineered and they can handle quite a bit of weight. Also, I think the tendency is for very heavy riders to ride rather slowly cause they are out of shape. Kinetic Energy = 1/2 mass times velocity squared. So speed will have a bigger effect on the bike then weight (within reason).

Also there are bikes and bikes. A touring bicycle with its heavier frame and heavier wheels should be able to handle a pretty heavy rider. I have seen riders over 250lbs ride light racing bikes so I guess a touring bike would handle 300+lbs pretty easily.

Sure there has to be a functional limit. Large riders should ride at least 23 mm tires for example and avoid those wheels with very few spokes. But as I said, big people tend to be very sedentary and they don't get on bikes. I guess if we when get fit 400lb and 500 lb people out riding bicycles, well then we will find out. I guess we could teach grizzly bears how to ride and find out fast.

Inoplanetyanin 05-27-03 10:38 PM

Check your formula for Kinetic Energy.

E=mc^2 is a formula for Energy realised from nuclear reaction where m is the mass of radioactive material, let's say plutonium and c is the speed of light.

Doesn't your formula look very similarly? ;)

FOG 05-28-03 06:51 AM

The problem is a heavy cyclist can still get quite a bit of speed up going down a hill, perhaps more than the lighter rider. This is a question of aerodynamics, skill and nerve, more than fitness. So when two riders going down a hill at 35 mph hit a pavement crack, the 130 pound rider on a 20 pound bike exerts roughly half as much force on the bike as the 280 pound rider on a similar 20 pound bike. This doesn't take into account things like sprung/unsprung weight ratios, flexing of the frame and differences in skill in absorbing bumps.

shokhead 05-28-03 07:59 AM

Just ride.

ChipRGW 05-28-03 08:51 AM

Weight is not an issue on almost all bike frames and forks. I am 280. I started riding at 330. I looked into this at the time and found that the vast majority of bike mfgrs will not give a weight limit on thier frames as it is not an issue. I've ridden a few different wheelsets and not had a real problem. You may, as a heavier rider either need a stout wheelset, or just true them a little more often. I would avoid the real low spoke wheels. I test rode a bike with Heliums and they seemed fine. I even hit some pretty hard bumps on purpose.
I think the only place where rider weight will be an issue is with extremely high rider weight like 350 and up, or with some of the ultra fly-weight bikes. It would be pretty pointless for a "clydesdale" to ride one of those anyway.

As shokhead says... Just ride...

Rockhound 05-29-03 08:50 AM

"over 250lbs and riding to lose weight"....

Ahem. I resemble that remark.

I weigh 250lbs and ride from 65 to 200 miles each week. This year, I've ridden about 1600 miles on this combination.

I ride an Aegis Aero Svelte carbon road bike with carbon Rev X wheels and I've never had a problem with my frame or wheels. I've contacted both Aegis and Spinergy and have been assured that my weight wouldn't be a concern on any "consumer type" bike, nor with MOST wheels. Some clipless pedals and ultralight racing wheels do come with pretty light weight limits, so that where i focus my worry.

In the past, riding on a steel Peugeot P10S, I did fine, as well. It was those darn spokes on it's light wheels that caused me such grief.

Btw, I haven't lost but a few pounds cycling, but I keep getting faster and stronger (I'm a old, fat fast man) . I did manage to lose about 4" in my waist, so the benefit is there in another form..

MichaelW 05-29-03 09:03 AM

As a 140lbs rider, I wonder if pretty much every bike that fits me is over-built to carry a much heavier rider.
Just how light can a bike get that is suitable for a flyweight with a responsive riding style ?

shokhead 05-29-03 10:42 AM

As light as you can afford.

ChipRGW 05-29-03 10:49 AM

How about this for a "light bike".

If you can afford it...

Michel Gagnon 05-29-03 10:51 AM

Lots of good comments so far, especially by FOG.

FOG, you comments about larger tires is an important one. A typical diamond frame has a lot of strength, so the two key factors are :
- lateral flexibility
- dynamic efforts.
On the latter, 700x37 tire for road touring or 26 x 2.25 or 2.5" tires for rough off-road riding even-out the bumps and the importance of dynamic efforts supported by the frame.

There also is a difference between a 250-lb rider and a 200-lb rider with 50-lb gear: the rider is centred on the bike and is usually sprung somewhat when the rider lifts his weight off the saddle.

Lateral flexibility or rigidity is often the real problem with a heavily laden bike.

MichaelW
Generally speaking, yes, a bike that fits you is over-built. However, you have options to improve performance:
- using a light-touring bike with proper gearing for heavier touring;
- using narrower tires.

I (170-lb) tour with my daughter (40-lb) on a trailercycle, using 700x32 (front) and 700x37 (rear). As a 140-lb rider, you could have the same comfort with 700x28 tires front and rear.

Regards,


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