surreal

You should getcha some drums

-rob

davidad

Wheels stand on their spokes regardless of the rim.

fietsbob

+1 on Drum hub brakes, weigh more , but don't need pads or service for a long time.
no bent discs to worry about either..
mine still work fine 20 years on.
new Sturmey rear hub is made to take cassettes, plus there is their IG hub models
front has a dynamo hub drum brake combo option..

rydaddy

No, I am not sure. I know what you are talking about... and yes, more spokes absorb a given load since they stretch more. I think the key reason DB spokes make a more durable wheel is because the strain cycles are focused at the center of the spoke instead of the j-bend. I suppose it's all related... so I'll back away from my previous post.

That must have been very frustrating. Sounds like you figured it out though...

rydaddy

Understood. However, the rim determines how many spokes do the 'standing'.

Retro Grouch 

I know that's "in the book" but can you explain it to me?

1. You can't push on a rope.
2. Even if you could, there's nothing for the rim end of the spoke to push against.

rydaddy

uh oh...

blamp28

For what it's worth, I am a heavy rider at 235. I use double butted spokes on my road bike wheels specifically because of durability. The wheels I am riding now have twice the mileage of the previous set which used straight Gage spokes. I ride Open Pro rims, 36 Wheelsmith 14/15 DB spokes laced to Ultegra hubs. I have not needed to true or tension them in 8000 miles so far. The provide a comfortable and reliable ride. Even though I like to build my own wheels, I bought these on sale and re-tensioned them out of the box to be certain that they were tight and right. If I were building from scratch, I would probably go with Velocity Aerohead in front and Aerohead OC in back to help even out drive side and non drive side tension.

noglider 

Standing on the spokes refers to the fact that a change in tension happens only at the bottom of the wheel. You might think that tension increases at the top spoke, since the frame pushes down at the hub and the hub pulls the top spokes down from the rim. But it turns out not to be true. Instead, the bottom spokes loosen a bit, and the rest of the spokes' tension remains the same.

cycle_maven

Actually, that's not entirely true- the loss of tension on the bottom spokes is accompanied by an integral increase in tension of the rest of the spokes, although it's a small amount. The total tension around the rim doesn't change much until a bottom spoke goes entirely limp and the system goes non-linear.

noglider 

Ah, true, but the biggest change happens at the bottom spokes. And this is how we figuratively push on a rope.

Retro Grouch 

So wouldn't it be more accurate to say "We pull a little less hard on the rope."? That bottom spoke isn't holding anything up it's just not pulling the hub downward quite as much. Would I be right if I were to attribute the lessening tension to a temporary deformation of the rim in that area?

Chombi

I just built a classic wheel mysoelf that do not have the traditional 32 spoke 3X lacing that many suggest.
My wheelset discription is as follows:
Wolber 28H Profile 20 tubular rims
DT SS Aerolite oval spokes with brass nipples laced 2X front and back
Stronglight Delta 28H hubs
All unused NOS parts (So it minimizes questions about hidden damage).
The robustness of the rims and hubs gave me confidence to do the 28H/2X lacing build, but I did get a few warnings from some C&Vers in the forum.
So far the wheels have ridden nice and true (very stiff ) without any need for retruing at all. I also made sure that I did the de/retensioning and spoke stress relieving towrads the end of the build for each wheel and that must have helped. The LBS manager I bought the Aerolite spoke from agreed that component make up on the wheels seem to be OK for a full 28spoke/2X lacing. It all really comes down to what parts you have for your wheels to make that final determination on what you can do in terms of spoke count and lacing.

Chombi

noglider 

All of that is fine. It's now down to an argument over which terms to use, and I don't mind which terms you like best. Physicists say there is no such thing as coldness. A refrigerator removes heat. Turning off the light doesn't add darkness. The trash that follows the subway train in the tunnel isn't sucked along by the train; it is pushed by air pressure that follows the train. These are terms that the physicist prefers, but if you want to add reduce tension on your spoke instead of pushing, that's fine, just as it's fine to add coolth to your attic.

DannoXYZ 

Yes, the amount of tension increase is distributed amongst a larger number of upper spokes. So their tension-increase is very minimal compared to the loss of tension in the bottom spokes in order to keep total-tension balanced. The actual tension-increase is small for the top spokes, and largest for the ones at the sides:


Going back to the OP's question, given identical tensions on two identical wheels, one using straight 14ga spokes versus one using 14/15ga DB-spokes, the spoke-stretch will be different for the same tension. To generate 125kgf tension, the 14/15ga DB spokes will stretch more than the 14ga spokes. This is the important distinction.

Now, when you add load to a wheel, the rim will flatten at the contact point on the ground and reduce the distance between the rim and hub. The amount of flattening at the bottom will be roughly the same for the same load between the 14ga straight versus 14/15ga DB wheel. This flattening amount is based upon the rim-stiffness and total spoke-tension (identical for both wheels). Let's take a theoretical value of 0.15mm flattening of the rim on the two spokes at the bottom. For the 14ga spokes, this has the effect of losing ALL tension from the two spokes at the bottom. For 14/15ga spokes, they may lose 60% of their tension.

Since 14ga straight spokes lost all tension in the flattened part of the rim on the bottom, there is no tension on the nipple and they unscrew over time due to vibration. The 14/15ga spokes at the same initial tension, but with more stretch, retains some of their tension and keeps the nipple from unscrewing. It is this nipple movement over time that causes the wheel with 14ga spokes to go out of true quicker and more easily than the 14/15ga wheel (especially over rough terrain with lots of potholes & bumps). It's not that the wheel is "stiffer" or "stronger", it's more durable and strays true for longer. If you measure lateral/vertical-stiffness, both wheels will be about the same. If you add more and more and more load to each wheel until it collapses, they both will take roughly the same load just before collapse.

BTW - I think we can support noglider's point that DB spokes causes less change in the spoke-tensions presented above. I don't have a graph, but I suspect DB-spokes would cause less variation in the peak & minimum spoke-tensions seen as a spoke goes around a wheel (same strain, different deflections).

Al1943

This is why I keep coming back to this place. There's always something to learn.
Good job DannoXYZ

noglider 

Super job, DannoXYZ. It's great to have you here.

I had no idea tension goes down that much. It's rather alarming.

john423

Surreal, I apologize if this seems like I'm bogarting your thread, but my question's pretty similar and I didn't wanna clog up things with a new post.

Just noticed I broke my second spoke in about 2 months today. I just recently added a rack and double-bagged pannier, and I'm a bit of a hefty boy (238 pounds right now, working on lowering that number).

Here's my bike. I've had it about 11 months. I'm a commuter. Probably about 10 miles a day, sometimes more, depending on how many errands I run.

I'm scared that seeing as how the bike cost me $330 or so new, having to re-spoke the back wheel or buy another wheel entirely is throwing away good money after bad. Are there bikes that are better built for heavy loads?

It's headed to the LBS, I'm nowhere near good enough to fix this, but I worry the LBS tries to "upsell" me because he sees me as a cash cow and I've been in 1000 times for various repairs/add ons. Would you:

1. Just have the spoke replaced?
2. Respoke the wheel with better spokes for fatboys like me?
3. Replace the entire wheel?
4. Say "screw it" and buy a better-built bike?

Thanks for y'all's help and sorry again for the Bogart.

Retro Grouch 

I think so too.

noglider 

john423, I don't know the bike, but $330 sounds a bit too low for a well made bike that you carry large loads on. I might say get a new bike, but I hate saying that. And as I said, I don't know that bike.

You certainly could buy a replacement wheel, and that's your lowest cost choice. Having broken 2 spokes, you're going to break all the rest of them, one by one, and replacing them won't improve the wheel.

But keep this bike. Don't sell it. You'll find a use for it. You'll see why it's good to have more than one bike.

Retro Grouch 

I'd probably pick #3.

1. I'm a believer in using a semi-expendable bike for local errand use so no new bike.

2. The discussion above indicates advantages to using butted spokes. In addition to that a more rigid rim will deform less at the bottom. The combination of the two (assuming a decent quality build) will produce a much more durable wheel than either by itself. The good quality build is neither rocket science nor some black art. Lots of people are capable of doing it. It just takes attention to detail.

DannoXYZ 

Thank you for compliments guys!

john423, what you are experiencing is spoke-fatigue failures. This is not uncommon with stock wheels on many bikes. The wheels come with spokes that are way undertensioned. This causes the bottom spokes to lose all tension under normal usage. This change from all-tension to no-tension again and again causes fatigue in the material and eventually it cracks. It's much, much better to have the spokes on the high-end of the range tolerated by the rim. In which case, the spokes doesn't go through as dramatic tension-changes as it rolls across the bottom.

It is also possible you've got low-quality spokes on that wheel, which has a lower-fatigue limit than higher-quality materials. Check the colour and uniformity of the finish to determine if it's stainless-steel spokes (preferred) or cad/zinc-plated plain-steel spokes. The plating process introduces impurities into the metal that weakens it. And there may be spots that aren't sufficiently coated and allows corrosion to occur.

Best bet is a new wheel with stainless spokes. Not that expensive, about $50-60 from a shop. And pay them an extra $10-20 to true it and bring it up to full-tension. Even with the factory wheels, this last step will extend a wheel's life tremendously.

dbikingman

John423 I'd go with the new wheel too. Even if you decide to upgrade the bike in the future the wheel could go to the new bike.

This has been a very imformative thread and written so that even I can understand it. Thanks

blamp28

+1
This is right on the money. properly tension wheels are even more important when carying loads including cargo or heavier riders like myself. Most factory wheels do not have enough tension but light riders usually don't end up putting enough load on them to discover this. Whatever wheels you end up with, make sure they are fully tensioned and you will be rewarded with longer lasting reliability. The extra money you spend now is less than the extra trips to the lbs later. Right on Danno

john423

I took the bike to a different LBS because I wanted to try the place out/get some new eyes on the bike. I talked a bit about some of the problems with my usual LBS, and they've got a great repair guy, but the owner can never give me a straight answer on when the bike will be ready (lotta "maybes," which is fine, I know they're busy) or even call me when it is ready, which is a bigger problem. I'll usually give him a few days after his latest "maybe" date and it's generally still not ready. Then I enter into this black hole of wondering when to call the guy again, because like I said, he won't call me.

Anyhoo, guy at different LBS suggested replacing this one more spoke, then we look at maybe putting on a new wheel if these troubles continue. He quoted $75-$80 for a new wheel, which isn't too bad. He was gonna put on another spoke and check the tension on the wheel to make sure it's not overtensioned.

Sounds good to me. $75-$80's not bad, considering. I thought a decent new wheel would cost $150 or so and I wasn't too keen on getting a wheel that cost half as much as the bike.

Thanks for your help, guys, I appreciate it. I at least know the direction I'm gonna go now, and that's key.

What's funny is I've constantly got gear lust to replace this bike, and one of the bikes I was looking at was a Torker Graduate. Well, I checked the specs, and they've got Alex rims, which I couldn't find a real good word about (much like the rims on my Schwinn), and 32 spokes, which means I would probably be in the same fix soon. Man, bikes is complicated