[cyclepath78]

I have a set of AC sprint 350's that I slightly exceed the weight limit on, I'm 205lbs. I had the rear wheel rebuilt with double butted tandam spokes and still managed to break the spokes on this 32 hole configuration. I have a smooth non mashing pedal stroke and I run 25mm tires. My local terrain is rolling hills with nothing excessively steep. Why is it that I continue to break spokes on a 32h wheel? Is it because the hoop is too lightweight? Must I now consider 36h options, a more stout rim, or both? Not sure if it makes a difference but all the spokes break near the hub.

I came across a set of Velocity Deep V's with WI hubs and DT comp x2 butted spokes with brass hardware, the price is a killer deal but I am hesitant to pull the trigger on another set of 32h wheels fearing I'll break a spoke again(and again and again...).

I dont require the lightest, latest and greatest super wheel known to man, but I would like to have a nice wheel that has some performance characteristics and not be a boat anchor.

Does anybody have some advise for me as to why I am breaking countless spokes on my current setup? Also, would the Velocity option be viable? If not, what would you reccommend?

 

[Zen Cyclery]

This could have been a few different things. Inadequate stress relief upon initial tensioning, lack of spoke prep on rebuild, defective spokes, etc... Sounds like the LBS who built these wheels needs to start digging and see if they owe you a rebuild.

 

[cyclepath78]

Would you feel that I would be safe to continue to look at 32h options?

 

[Zen Cyclery]

Well, I don't think that spoke count is the only factor here. A poorly built 32 hole wheelset is going to be far less durable than a well built 20/28. By well built I mean properly stress relieved, with uniform tension throughout.

 

[grandsalmon]

This could have been a few different things. Inadequate stress relief upon initial tensioning, lack of spoke prep on rebuild, defective spokes, etc... Sounds like the LBS who built these wheels needs to start digging and see if they owe you a rebuild.

No worries mate, Like Zen says, a wheel properly built; tensioned, relieved and held w some prep should do you better. I am heavier than you, mash when I climb, on a few sets of less than 32 ct spoked wheels. And they are years old now. If a wheel isn't 'standing' -decently built, the spokes walk themselves off a cliff, the first to hit the bottom are the ones that are breaking. Even and locked-tension is key, and it is easy to stay on top of this by checking after the first few rides.

 

[cyclepath78]

Well, I don't think that spoke count is the only factor here. A poorly built 32 hole wheelset is going to be far less durable than a well built 20/28. By well built I mean properly stress relieved, with uniform tension throughout.

Gotcha, that makes good sense.

 

[cyclepath78]

No worries mate, Like Zen says, a wheel properly built; tensioned, relieved and held w some prep should do you better. I am heavier than you, mash when I climb, on a few sets of less than 32 ct spoked wheels. And they are years old now. If a wheel isn't 'standing' -decently built, the spokes walk themselves off a cliff, the first to hit the bottom are the ones that are breaking. Even and locked-tension is key, and it is easy to stay on top of this by checking after the first few rides.

Good info. It can be a costly endeavor finding a good local wheel builder.

 

[Mike T.]

As the others have said, the first suspect here is a poor build quality. For that we need adequate tension and equal tension with all stresses relieved. If you read my site you will find what that entails. That doesn't take rocket science to achieve but it does take knowledge and a bit of skill.

Then, when the wheel is properly built, it has to stay stable because if it's flexing all over the place the spokes will be subject to wild tension fluctuations which will lead to metal fatigue. I just looked up the specs of that wheelset and it must have a very light rim as the set is 1410 grams with lots of spokes (28/32). While you're not monstrously heavy (at 205lbs) I think you're at the end of the scale for that rim. I'll bet it's a sub-400 gram rim which, IMO, isn't enough for you. 450g would be much more safe.

I think the thick tandem spokes are not helping here. Regular DB spokes (2.0/1.8/2.0) would absorb the tension swings better. Those spokes are well able to deal with body weights far greater than yours.

With the tension equalization and stress & spoke windup relief info you will get from my site you will be well able to judge your own wheels even if you don't rebuild them yourself (which you could do). You will be able to judge when you get them back from the builder how well they were done and whether they are staying stable after the first ride, a few rides and after many rides.

It could also be that the rim is somewhat bent and it's taking unequal spoke tensions to pull it into true. When this has to be done we can't achieve equal tensions anymore and some spokes have to do more work than others and therefore fatigue faster.

You mention 25mm tires which are a great idea for your weight - but only if they are at the correct pressure. Those tires at 130psi are not going to be any more absorbent than 23mm tires at 100psi. But I'll assume you're using sensible pressures for your weight (which would be about 90-100psi).

Your weight isn't the issue here unless it's linked to improper equipment for that weight. I once had a really heavy local boy bring a rear wheel to me. He was far heavier than you. He'd broken lots of spokes and the LBS was getting rich from replacing them. I re-built his wheel with new spokes and gave them plenty of tension and I stress-relieved the snot outta them. I saw him a long time later and he was not breaking spokes anymore.

 

[dcgriz]

@cyclepath78

The previous suggestions given is all good information and typically the cause of the breaking of spokes. In addition, another thing to look at is the tandem spokes you said you are using. Tandem spokes are thicker at the elbow (around 2.2 to 2.3 mm) than standard spokes and if the hub drilling does not offer enough clearance (diameter of hole not large enough) for the elbow to be fully seated and properly aligned then the elbow is not fully supported and the spoke becomes susceptible to breakage.
As others already have said, what you are experiencing appears to be the result of poor built quality. No need to increase the number of spokes to 36.

 

[looigi]

Where are the spokes breaking?

 

[cyclepath78]

As the others have said, the first suspect here is a poor build quality. For that we need adequate tension and equal tension with all stresses relieved. If you read my site you will find what that entails. That doesn't take rocket science to achieve but it does take knowledge and a bit of skill.

Then, when the wheel is properly built, it has to stay stable because if it's flexing all over the place the spokes will be subject to wild tension fluctuations which will lead to metal fatigue. I just looked up the specs of that wheelset and it must have a very light rim as the set is 1410 grams with lots of spokes (28/32). While you're not monstrously heavy (at 205lbs) I think you're at the end of the scale for that rim. I'll bet it's a sub-400 gram rim which, IMO, isn't enough for you. 450g would be much more safe.

I think the thick tandem spokes are not helping here. Regular DB spokes (2.0/1.8/2.0) would absorb the tension swings better. Those spokes are well able to deal with body weights far greater than yours.

With the tension equalization and stress & spoke windup relief info you will get from my site you will be well able to judge your own wheels even if you don't rebuild them yourself (which you could do). You will be able to judge when you get them back from the builder how well they were done and whether they are staying stable after the first ride, a few rides and after many rides.

It could also be that the rim is somewhat bent and it's taking unequal spoke tensions to pull it into true. When this has to be done we can't achieve equal tensions anymore and some spokes have to do more work than others and therefore fatigue faster.

You mention 25mm tires which are a great idea for your weight - but only if they are at the correct pressure. Those tires at 130psi are not going to be any more absorbent than 23mm tires at 100psi. But I'll assume you're using sensible pressures for your weight (which would be about 90-100psi).

Your weight isn't the issue here unless it's linked to improper equipment for that weight. I once had a really heavy local boy bring a rear wheel to me. He was far heavier than you. He'd broken lots of spokes and the LBS was getting rich from replacing them. I re-built his wheel with new spokes and gave them plenty of tension and I stress-relieved the snot outta them. I saw him a long time later and he was not breaking spokes anymore.

Wow, lots of great info both here and at your site. Thank you! As far as tire pressure goes I run 110 on the rear. It starts to feel too bouncy below 105.

 

[cyclepath78]

@cyclepath78

The previous suggestions given is all good information and typically the cause of the breaking of spokes. In addition, another thing to look at is the tandem spokes you said you are using. Tandem spokes are thicker at the elbow (around 2.2 to 2.3 mm) than standard spokes and if the hub drilling does not offer enough clearance (diameter of hole not large enough) for the elbow to be fully seated and properly aligned then the elbow is not fully supported and the spoke becomes susceptible to breakage.
As others already have said, what you are experiencing appears to be the result of poor built quality. No need to increase the number of spokes to 36.

I hate to lose faith in my lbs because they treat me so well but I have had two sets of rebuilt wheels from them that experience broken spokes. One being a Stan's mtb wheel and the other my AC's. The AC's have lots of miles on them and they are ridden between 100-150 miles per week for the past 4 years. I think it's time to retire them. I've noticed a Boyd wheelset that is an Al clincher 24/28h rated up to 240 lbs at a respectable weight(1600g ish...) offered at $400 bucks with a 2yr warranty. Those are looking like a good option. I want a wheelset that can handle year long training and still perform well on my group rides.

 

[cyclepath78]

Where are the spokes breaking?

Very close to the hub. Sometimes on the elbow and sometimes just below. I just want a solid training wheel that can be counted on for at least a few years or about 20k miles without needing a rebuild.

 

[Mike T.]

As far as tire pressure goes I run 110 on the rear. It starts to feel too bouncy below 105.

Mr Dunlop would be so happy if he heard that. That was his intent.

 

[dcgriz]

I hate to lose faith in my lbs because they treat me so well but I have had two sets of rebuilt wheels from them that experience broken spokes. One being a Stan's mtb wheel and the other my AC's. The AC's have lots of miles on them and they are ridden between 100-150 miles per week for the past 4 years. I think it's time to retire them. I've noticed a Boyd wheelset that is an Al clincher 24/28h rated up to 240 lbs at a respectable weight(1600g ish...) offered at $400 bucks with a 2yr warranty. Those are looking like a good option. I want a wheelset that can handle year long training and still perform well on my group rides.

I understand your hesitation regarding your LBS but the results speak for themselves. The Boyd Rouleur might do it for you although I believe the 24/28h may be marginal as you are at the upper side of their range. The 30mm deep rim will add to the wheel strength but whether or not or how often you may be breaking spokes will depend on how soft you are with the wheels; don't consider the 240lbs rating in absolute terms.
A more conservative spoke count, IMO, would be 28/32h specially considering your last statement "I want a wheelset that can handle year long training and still perform well on my group rides". The extra 4 spokes on each wheel will not slow your group riding in any meaningful way and will give you the extra insurance in terms of strength.
If there will be a problem with the 28/32h arrangement it will be meeting the $400 price range because of hub availability. A 32/32h with hubs the like of Ultegra will be well within the $400 range but a bit overbuilt on the front wheel. If you need to maintain this budget, you will need to decide between more "racy" or more "durable".

 

[Kerry Irons]

I just looked up the specs of that wheelset and it must have a very light rim.

IIRC the AC 350 claimed a 350 gm rim, though maybe they didn't achieve that in practice. Anyway that is WAY to light a rim for a 200 lb rider. Building a durable wheel for a heavy rider with a rim that light is a daunting task if not impossible. Trying to make up for it with heavy gauge spokes makes no sense.

 

[Mike T.]

IIRC the AC 350 claimed a 350 gm rim, though maybe they didn't achieve that in practice. Anyway that is WAY to light a rim for a 200 lb rider. Building a durable wheel for a heavy rider with a rim that light is a daunting task if not impossible. Trying to make up for it with heavy gauge spokes makes no sense.

True that. I'll stand by what I said earlier - a 450g rim is about right.

 

[Tunnelrat81]

Wow, lots of great info both here and at your site. Thank you! As far as tire pressure goes I run 110 on the rear. It starts to feel too bouncy below 105.

If 105 psi is starting to get too bouncy, maybe your pedal stroke isn't as smooth as you claim. 105 psi on a 25mm tire should be plenty firm. Remember last year's Paris-Roubaix reports that Tom Boonen was running sub-70 psi on his sew-ups. I doubt he bounced his way through that entire race. I'd try lowering the pressure a bit, and see if you get used to it after a 10-15 rides. It could just be a perception thing, and once you're used to the new feel, it won't even cross your mind. I agree with the above too. On the right rim, 32h should be plenty. I weigh ~147 and wouldn't expect that 1410 gram wheelset to be completely trouble free for me.

-Jeremy

 

[cyclepath78]

If 105 psi is starting to get too bouncy, maybe your pedal stroke isn't as smooth as you claim. 105 psi on a 25mm tire should be plenty firm. Remember last year's Paris-Roubaix reports that Tom Boonen was running sub-70 psi on his sew-ups. I doubt he bounced his way through that entire race. I'd try lowering the pressure a bit, and see if you get used to it after a 10-15 rides. It could just be a perception thing, and once you're used to the new feel, it won't even cross your mind. I agree with the above too. On the right rim, 32h should be plenty. I weigh ~147 and wouldn't expect that 1410 gram wheelset to be completely trouble free for me.

-Jeremy

I think you are right about the perception thing. I will do some experimenting with psi on upcoming rides. I do notice that on my front wheel at 100 psi when I stand up for a climb with the added weight over the bars my front tire "looks" like its going flat but it doesn't translate to that sensation of "feeling" flat. That's more or less why I run 110 on the rear. I'm afraid the looking flat appearance would lead to pinch flats and rim strikes in the odd event of finding a pothole.

One mans smooth is another mans rough, I'm quite sure my pedal stroke could use some polishing

 

[dcgriz]

I think you are right about the perception thing. I will do some experimenting with psi on upcoming rides. I do notice that on my front wheel at 100 psi when I stand up for a climb with the added weight over the bars my front tire "looks" like its going flat but it doesn't translate to that sensation of "feeling" flat. That's more or less why I run 110 on the rear. I'm afraid the looking flat appearance would lead to pinch flats and rim strikes in the odd event of finding a pothole.

One mans smooth is another mans rough, I'm quite sure my pedal stroke could use some polishing

Not sure what the "tire looks like its going flat" really means.
Check this out about tire pressures: http://www.bikequarterly.com/images/BQTireDrop.pdf