nom nom >:f

Never heard it said that way before, but I'm guessing they're referring to the fact that the wheel supports weight by standing on the bottom spokes, rather than hanging from the top ones, as you'd intuitively think.

Obviously it's not simply standing on them, since every spoke is in static tension, the bottom spokes just lose some, which has the same effect as compression, but without buckling the spoke.

By far the majority of load is carried by a few spokes at the botom of the wheel, not the full bottom 16 in a 32 spoke wheel.

Not quite.

The weight is not on the bottom spokes, but along the top 180 degrees of the wheel.

Spokes have no strength in compression, but a lot in tension.

The top spokes transfer the load up to the rim, the bottom spokes (all of them actually) are holding the rim in a stiff strong shape, so it is the rim that is then transfering the load to the ground.

Other way around, but I'm referring to the interpretation given in The Bicycle Wheel; top spokes prestress the bottom spokes in order to GIVE them strength in compression, same way steel reinforcing bar can let concrete members take loads that are effectively tension loads. Only the bottom few spokes see significant changes in tension when the wheel is loaded. Either way, pretty sure it's a matter of semantics because it's the balance of forces that are important, and without the other 16 spokes the wheel isn't going to be a wheel.

DH wheels don't have to be bomb proof when you have 8/9 inches of travel to soak up the bumps also.

There is no force being pushed down on the bottom spokes. the strength comes from the top and the shape of the rim.

Some of the strongest wheels may have very few spokes:
http://i120.photobucket.com/albums/o...ts/WHEL-25.jpg
This Shimano MTB wheelset is known to be one of the strongest in existence, but notice the special lacing pattern, hubs and rim.
Review with info: Shimano WH-R540

Those are road wheels.

These are Shimano mtb. wheels: http://bike.shimano.com/publish/cont...bm.512.384.gif

A lot of the time, the FG riders are young, and just starting out in the world, careerwise, or not even a career yet, just a job or in school, so yeah, I can understand a fixation on cheap pricing.

Buy nice or buy twice.

Do you mean the WH-R540? I see MTB people using them, and mine are 26".

Can you find the Shimano link for these mountain bike WH-R540 wheels? I've looked on their website and just see their WH-Mxxx wheels with the M standing for Mountain; like the R stands for Road.

Are people using these as 29"er wheels? You say yours are 26". Did Shimano stop making them?

your Maddy sucks! but only 'cause you stole my vintage headbadge idea. ;0)

:lol: I didn't 'steal' it. I was inspired by it.

You know my Madison rocks!

wow so many posts... ok so, I'm getting a special treat to be able to order some stuff wholesale... Mostly I am gathering parts for 2 wheel sets... 1 is a track set that will see road too (but not a ton) and the other is a polo/busting around set... So as I look in the catalog alls I see is 32h... Even the velocity chukkers are only offered in 32h (this is not a super big distributer mind you). Its just sort of frustrating to see when you have always ridden/ been told 36h is the way to go considering your size... I dont know where I am going with this, I just got off work...

So many questions... I only found a link to a few PDFs of exploded views of both the rear and forward wheel. For now.
I've seen several of these wheels IRL, and they were all 26". Online, everywhere I looked, they have been used by MTB guys. That's all just anecdotal, though, so make of it what you will.
I do believe Shimano isn't making them anymore, but I'm not 100% sure.

Only if there ARE no bottom spokes.

"Bicycle Wheel as Prestressed Structure

J. Engrg. Mech. Volume 119, Issue 3, pp. 439-455 (March 1993)

C. J. Burgoyne 1 and R. Dilmaghanian2
1Univ. Lect., Engrg. Dept., Univ. of Cambridge, Trumpington St., Cambridge CB2 1PZ, United Kingdom
2Formerly, Steel Construction Inst.

Issue Date: March 1993

Bicycle wheels achieve their structural efficiency by making use of prestressing in three ways. Tests show that the bottom spokes carry virtually all the load by compressive forces, which reduce the tensile prestress set up in the spokes when the wheel was made. The test results are compared with an analysis that considers the spokes as a disk that can carry force in one direction only. This is shown to give good agreement, as does an analysis that considers the rim as a straight beam on an elastic foundation. The behavior of the wheel with an inflated tire is also considered, and it is shown that good comparisons with theory are obtained if the reaction from the road is assumed to be distributed over a specific length of the rim. Prestressing is shown to be important also in the mechanism by which the various forces are transmitted through the tire from the road to the rim.

©1993 American Society of Civil Engineers"

There was a "Reply" to that article, published 2 years later, but my institution doesn't have access to that journal. Can you access it? Maybe there's some interesting counter argument.

I might be able to, but to be honest I'm WAY too lazy to go through the motions. So instead, here's another one that's kind of cool: http://www.rose-hulman.edu/~fine/FE2002/Projects/Hartz.pdf

Check out the exaggerated deformation and strain diagrams on pages 8 and 9 of the PDF. There's barely any tension increase in the top half of the wheel, but significant reduction at the bottom because of localized deformation.

I'm not really pushing the point, though. However you describe it, the wheel supports a load through a change in the net internal force, and a bottom spoke in compression is equivalent to one in reduced tension.

Can't we all just get along???

http://3.bp.blogspot.com/_wvoLtwni0k...ight_thumb.jpg

http://3.bp.blogspot.com/_wvoLtwni0k...ight_thumb.jpg

+

Cyclist Fight

=

????

Deep Vs come in in drillings from 16h to 48h, and TheBikeBiz claims to have them all.

Ben's has a few options for 36h Chukkers, and they're in stock. They also stock some in 48h.

You can even get 36h Aerhoeads if you really want to.


I think you just need a better distributor, or to contact them to see if they can order the rims you want. Alternatively, you could get the hubs, spokes, and nipples from them at wholesale and order the rims retail from somewhere else. But you do have lots of 36h options, and even some in 48h.

Man cyclist fight... those guys clearly have 0 upper body strength, they should learn kickboxing

Also, regarding our little standing-vs.-hanging argument, the guys in this thread already put way more effort than I, at least, am going to, and with much greater ability.

That's probably what I'd be like fighting with normal shoes on, too.

The question is, does the compressive stress completely compensate the tensile stress "built in" during the wheel manufacture? I realize that this is a practical question, because it depends on
- the weight of the rider and
- the tensile stress the wheelbuilder (or machine) that put "built in" each spoke, during building.

I think this is the most interesting discussion I have had on here for a long time.

I am going to get my nerd on and read up more on this.
http://thepioneerwoman.com/homeschoo...02/nerdie2.jpg


You guys got any links to any whitepapers on how the load forces in a spoked wheel are transmitted to the ground?

And to think that all the OP wanted to know was where to buy a 36 spoke wheelset...

doesn't he know how to use a search engine? sheesh.

And for the record, Mavic 823 rims laced to Hadley hubs are the strongest MTB wheelset you can get.

God, I'm sorry OP. I thought there was a simple answer to my question.

You mean, does the spoke undergoing the compression-equivalent-stress (the one or two at the bottom) lose all tension? It can, but that's associated with loads WAY beyond what the wheel is designed to take, e.g. a hard landing after a jump or hitting a curb or something.

When a spoke loses too much of its tension its into the zone where failures happen. Too little pressure on the nipple threads mean they can unscrew themselves if there was some residual twist in the spoke or they can turn themselves from vibration. Low tension at the bottom means you lose the lateral forces that stabilize the rim at that point (I think) so you can taco the wheel, and there are fatigue issues associated with spokes that go slack, as well as ones that are too tight