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Rider Weight and Wheelset Question(10 posts)

Rider Weight and Wheelset QuestionBrianNYC
Oct 8, 2002 8:13 AM
In Zinn and the Art of Road Bike Maintenance, he writes that any rider who weighs more then 190 lbs. should use a 36 spoke wheel (or something to that effect, I might have the spoke count wrong). I weigh 200 lbs. and don't think there is any healthy way that I can weigh less then 190, so that is not an option. My question is, with all of the different spoke configurations out there with different lacing patterns and spoke count, is there a simple calculation/rule to use to figure if a given wheelset's spokes will be able to take the weight? Given the price of wheelsets, I would rather know before I spend the money that wieght will not be the cause of their demise.

Thanks
re: Rider Weight and Wheelset Questionmikepo
Oct 8, 2002 9:16 AM
I'm also a big rider (6'4"/210, down from 250, but unlikely to go below 200), so I paid careful attention to Zinn's advice. The way I figure it, if I break a spoke, then I want as many left to take the load until I get stopped. Since the most reasonable choices (from a $$ standpoint) are 32 or 36, I'd go with 36.
re: Rider Weight and Wheelset QuestionPaulCL
Oct 8, 2002 9:21 AM
I can't answer the question on any calculation, but I can give you first hand anecdotal experience.

Personally, I am around 190lbs. I could lose 10lbs and be healthy ...but I love them carbs too much!! I ride 18spoke front/24 spoke rear Speeddream wheels. I've ridden them for two years. My only problem is two broken spokes in the last month that's in over 7000 miles total- not bad.

I rode with a guy who was 6'7" tall and well over 250lbs for a week last year. He rode Ksyriums (18f/24r spokecount) and never had a problem in over 7000 miles! Nada, zip, zero problems.

Remember, the Zinn book is several years old. The technology has come a long way since then. You would be very safe on 28 or 32 spoke Mavic Open pros.

Good luck. And alas, neither of us will ever be able to ride a DeRosa Merak...bummer.....
I called Campy to find answers...MXL02
Oct 8, 2002 10:09 AM
and like all things, the answer is "it depends". Not only on your weight but how much you ride, and under what conditions. I weigh similar amount, and have broken
b TWO
32 spoke rims riding on rough roads. Both were cheapos but still, the message was clear. Campy recommended custom built wheels, 32 front and 36 back, with four cross pattern on the rear. They are Torelli hubs with Mavic CXP 33 rims. They are
b Bombproof!
I have a similar pair of wheels 32/36, built up with record hubs and open pro rims. These too seem to be bombproof. I ride these wheels on most of my training rides.

The lighter wheelsets: Ksyriums and AC 420's I ride only on special occaisions, fast rides, quasi-races etc. with the understanding that the more stress I put on them the higher the chance of breakage.
I called Campy to find answers...bobobo
Oct 8, 2002 10:48 AM
The Zinn book rule deals with user, custom built wheels using OEm hubs, rims, and standard spokes. For prebuilt factory wheels such as Ksyriums, Campy Neutron, Campy Eurus ..etc... you can't apply the Zinn rule. These wheels have specific application engineered hubs, spokes and rims with design specs that are completely different from your typical built up wheel using standard rims, spokes, nipples and hubs. That is why these wheels can often get away with far fewer spokes than a custom built up wheel at a bike shop.

I know two guys who rode Speedream Aerolights. They said they were nice fast wheels, they also both had problems with trueness and broken spokes withing 1 season of use. I guy had bigtme problems with his AC classic rear hub which he thought was a piece of you know what.
SpeeddreamsPaulCL
Oct 8, 2002 11:25 AM
I've heard of the problems with the AC hubs, hence, mine are built with a rear record hub and front AC.

Funny, I didn't have any spoke breakage problem until last month. I've broken two in the last month. In all fairness, I used to break spokes on a regular basis on my Mavic Open Pros. I guess that's part and parcel of riding a light roadbike when you weigh 190lbs +. By the way...Dave Thomas mailed me three spare spokes last week for free. Nice service.
doesn't really matterJofa
Oct 8, 2002 2:09 PM
The difference between 32 and 36 spokes is slight, regarding durability. Build quality has a far more significant effect: If a wheel's spokes are not properly stress-relieved they will fail, far sooner than those which have seen this critical process (and furthermore will probably go on for ever). A 32 spoke wheel will deform more in the case of a spoke failure, but is still usually rideable.

Spokes - like most bike components - only fail as a result of fatigue. In use the spokes of a 36 spoke wheel only experience about a third of their yield strength, a 32 spoke wheel slightly more. Riding only detensions spokes: they are at maximum tension at rest. Therefore heavy riders only cause a correspondingly higher tension relief, not an increase. It is repeated small stresses - returns to maximum tension - which cause failure. Consequently there is no way to assess the durability of a wheel until spokes fail: surviving a large impact tells you nothing useful about a wheel, which might still fail during gentle riding.

It is the rim which determines the maximum spoke tension, above which it will collapse into a saddle shape. Heavy riders should look for the strongest rim that is practical. You, however, are nowhere near heavy enough to need exceptionally strong rims. The ordinary rims you already know about will be fine, as long as the wheels are well-made, and if they aren't then they'll be no less likely to fail under a rider half your weight. Spoke pattern is aesthetic and irrelevant, as long as they are mostly tangential (2/3/4 cross).

Specialist factory-built wheels with few spokes have various alleged advantages and disadvantages. They generally are warrantied against spoke failure, but can be difficult to repair if they need it: the parts are frequently non-standard and not freely available. Also the fewer the spokes the more unrideable is a wheel if one does break. My recommendation is for ordinary wheels with Mavic or Ambrosia rims, handbuilt by a 'reputable' builder. This quality can be difficult to divine: asking gently about stress-relieving is one way- if your subject doesn't know what you are talking about then look elsewhere.

Jofa
re: Rider Weight and Wheelset QuestionSnowBlind
Oct 8, 2002 2:13 PM
at 235, open pros 3x 14/15, have 12000+ miles on them, not a broken spoke.
However!
riding buddy has same thing, he is 190, breaks a spoke every few months.
The diff? His next door neighbor (ex. wrench) built them. (granted he is a good guy, a decent wrench, but a lousy wheelbuilder)
A competent build is the key, a sloppy build will give you problems.
As always, thanks to all for the advice (nm).BrianNYC
Oct 9, 2002 5:20 AM
As always, thanks to all for the advice (nm).bobobo
Oct 9, 2002 7:15 AM
How would people rate the build quality of places like Colorado Cyclist and excelsports?