mrfreezesdefy3

Ok so posted another thread in the road forums and thought I'd get an answer but here it is I own a 2015 giant defy3 factory run bike ,I've had 2 spokes break at 2 different times , as competitive as I am I've decided to get some more wheels ,
1 what makes a spoke break ?
2 how can I prevent it?
3 I've decided to get me some hed belgium plus wheel and disc ready hubs , should I order 6 extra spokes ?
4 I'm 270lbs and was thinking 32 spoke front and back what are your thoughts ,, ?? Any help would be appreciated ,,,since I'm fixing to drop a grand on wheels ,

Haff

I weigh a little more than you do and I decided to upgrade my Defy wheels to a 36-hole set. I think these will take all the abuse I can reasonably hand out.

As for what breaks spokes? They are just metal. they are put under enormous tension and many of them bend a sharp angle at one end. Too much tension or too sharp an angle and they will pop. When a bike is stationary it might be fine, but once you sit on it, or start riding as the wheel turns the individual spokes will see a cycle of more and less tension. this wears them and can lead to failure as well.

TrojanHorse

Usually what breaks spokes is when they are so unevenly tensioned one of them will actually go slack while you're riding. A well-tensioned wheel will last a lot longer than one poorly built. Obviously, if you break one spoke you're putting extra strain on the remaining adjacent spokes, and the internet rule of thumb is that after you've broken 2 or 3 spokes, you should get the wheel rebuilt.

Drew Eckhardt 

Fatigue, with the number of cycles survived dependent on average stress and magnitude of the cycle.

Spokes come from the factory with high average stress because not all of the elbow is taken past its elastic limit.

Variation in front and rear drive side spokes comes from rider weight slackening them as they pass the ground at about 750 cycles per mile.

Non-drive-side spokes are at lower tension than drive side, and can go slack so they bend back and forth like paper clips.

Achieve uniform high tension so you don't break NDS spokes. Stress relieve so you don't have parts of the elbows which didn't make it past their elastic limit.

You can squeeze near parallel pairs of spokes towards each other on each side of the wheel or twist the spokes about each other at their outer crossing using something softer like a platic screw driver handle, old left crank, or brass drift.

79pmooney

Spokes commonly break from: loads that are too high and loads that go to zero frequently. More spokes helps the first problem but not the second. Wheels built with uneven tensions often run into both problems and will be problem wheels. Nor enough tension means that the lesser loaded spokes will go slack at the bottom of the wheel rotation as the hub and rider weight are basically "hung" from the upper spokes. Cycling through slack then loaded every wheel revolution is similar to what engineers do to metal samples to test for fatigue limits.

Sadly, the modern bicycle has rear wheels that push the limits of spokes because of the extreme dish used to accommodate the many cassette cogs. Enough tension to keep the left side spokes tight enough will be very close to too much for the right side spokes. One way around that issue is the rims with asymmetric spoke eyelets.

Best bet is to go with wheels built by quality builders with plenty of spokes. Hand built by a reputable builder is one approach. A reputable pre-built wheel is another. Ask around. Ask folk who weigh and ride like you do what they use. (How we ride counts for as much as what we weigh. There are big folk who are kind to wheels and little guys who will destroy anything.)

Ben

hayden52

Counter-intuitively, spokes tend to break when they don't have enough tension. The spoke tension is highest when the wheel is unloaded, and when weight is put on the wheel the lower spokes take up the weight and their tension is reduced. If the initial tension is not high enough, the spokes will go slack (no tension) and as the wheel turns they will return to their normal tension. This going slack and returning to high tension puts a lot more stress on the spokes (especially at the elbow bends) than if the spoke started at a higher tension and reduced to a lower tension but did not go slack.

I suspect your stock wheels did not have enough tension to hold your weight. The solution is to tighten up the spokes. If you don't know how to do this, get your wheels re-tensioned at a reputable shop.

RocTurk

I am guessing broken spokes were on the rear wheel, right? Pretty much all answers are true. Fatigue, tensions, etc. I don't want to generalize but seems like Giant is earning its price advantage via using crappy wheels. You said your bike is a 2015 bike, so even if you're an avid cyclists, you haven't put over thousands of miles yet probably. I'm around 240 lbs, and on my hybrid Giant Escape, I started to break spokes after 800 miles of riding, one, two, ... unfortunately the LBS was charging 35$ to replace a broken spoke and after the third broken one, I've invested in a set of machine built Mavic A319 touring wheels 36H front/back DT swiss double butted spokes ~300$ tax/labor included and never had a broken spokes since. They are not the lightest wheel by any means but I wasn't looking for performance on my hybrid. My road bike came with Mavic CXP22 wheels, after reading couple bad reviews from fellow clydes, I replaced the rear wheel with a hand built cxp33 32H dt competition spokes 105 hub without facing any issues with the stock wheel. it's been 1600 miles since and no issues so far.

It won't cost you much retensioning the spokes but if the material is bad, no matter what you do, you'll still be breaking spokes one after the other. My suggestion is get a set of custom built wheels that can hold your weight well. Since you're 270lbs, 32H front/36H rear would be a good combination. There are couple reputable wheel builders on internet if you don't have a local builder around. Also, couple companies offer stock performance wheels for heavy riders. Boyd cycling says there is no weight limit for its Altamont wheels with 28/32H option. 700$ investment though. Why don't you email them and ask what they think?

Drew Eckhardt 

Nope.

1. Modern rims can accommodate a lot of tension, with manufacturers' official ratings reaching 130kgf. I only got 105-110kgf out of the box section wheels I built using Jobst Brandt's tensioning method of alternately adding tension and stress relieving until the wheel deforms in waves indicating you've reached its elastic limit at which point you back off half a turn, true, and be happy.

Deep profiles for aerodynamics also make them stiff so you can run high tension without approaching their elastic limit.

Thick spoke beds allowing low spoke counts with adequate total tension also support traditional counts at high tension.

2. Butted spokes have much more elongation at a given tension, especially ones with 1.5mm center sections whether straight or flattened into an aero shape as with the Sapim CX-Rays and DT Aerolites that are ubiquitous on small manufacturers' boutique wheels. Stretch is inversely proportional to cross-sectional area squared so 2.0/1.5mm spokes like DT Revolutions stretch 80% more at the same tension as 2.0mm straight-gauge, 2.0/1.6mm spokes like DT Competition Race 56% more, 1.7mm like 2.0/1.6/1.8 DT Super Comp 38% more, etc.

3. Deep rims deflect less due to stiffness so they require less spoke stretch to maintain tension as spokes go slack passing the bottom of the wheel.

Obviously a symmetrical box section rim with plain 14 gauge spokes wouldn't be prudent for a 270 pound Clydestale, although there are much more appropriate component choices.

mrfreezesdefy3

OK the first time my rear spoke broke it was on the drive side, and it broke on ,Sunday when I was 3miles into a 51 mile ride it broke on the rear non drive side , my lbs said that giant would warranty the wheel , he fixed the spoke today , so I'm hearing to get my hed Belgium's 36 spoke in the rear and 32 in the front?? I'm a very competitive person ,and have realized I need to get rid of some rolling weight to make it better for me,
As I watched the tech as he fixed my wheel and I can't understand why and I know the drive side is not as bulging as the non ,as a mechanic seems like you'd want it even ,but yet I'm no engineer

P.s. my spokes are breaking at the thread ending on my spoke where the nut ends like a 1\4" before the rims ,to me its where it was finished being threaded on the lathe

I just want to make the right choice for my new wheels and don't want to blow a grand on the wrong thing

jsigone

sometimes its just a good case of bad luck.

If you are getting customs and odd ball spokes, then YES get extra spokes. In the long run it will cost you much more in shipping a couple spokes if you didn't do so now. My LBS swears by dt but I like sapims. In a pinch I'll have them fix it will DT stuff, but nor preferred plus I don't break spokes often.

mrfreezesdefy3

Well the more I surf the more confused about what to buy my budget is a grand any recommendations??? A good quality aerodynamic rim and quality hub and spokes, just don't wanna keep breaking stuff ,heck maybe it's normal
BTW at end of the month I'll be at 1800+miles since I've started my journey ,I guess bikes are like cars you can wear them out , but I'm pulling alot of preventative maintenance on my bike , I would appreciate any ideas , some one posted boyds , he only lives an hr from me might give them a call just a lil shy of carbon rims because of my weight

VCSL2015

I broke a spoke on my road bike a couple days ago which came to light yesterday on my long ride. The top of the spoke was loose and the bottom piece spinning inside the rim. I contemplated using a hair strand (since i was far from home) to tie the spoke to its neighbour to keep it from making noise and falling off but then remembered i had a tiny headphone clamp i set on my bike wires 2 days before my ride. (genius!) thats the last time i let the kids take me off roading on my road bike LOL!

GravelMN

Breaking spokes is never "normal".

Most spokes break at the J-bend due to inadequate/uneven tensioning that results in 1,000s of cycles of the spoke going slack then tight. This fatigues the metal and sooner or later something's got to give. Knicks and damage can also cause stress points subject to failure. If you've ever dropped a chain to the inside of the cassette, always inspect the spokes carefully. If you are breaking spokes at the nipple end, check to make sure your spokes are long enough. They should come to at least very close to the bottom of the screwdriver slot in the nipple head.

I've never seen a spoke fail mid-shaft unless there was considerable damage done to it.

To prevent spoke failure:

- assure that spokes are of sufficient length to fully engage the nipples
- make sure that the spokes fit and are properly seated in the flange holes
- check that spoke tension is appropriate for the build and relatively even
- have new wheels trued and tensioned and get them rechecked after a couple hundred miles
- use butted spokes as the extra "give" in the middle actually helps protect the elbows
- replace any broken spokes ASAP as riding with them increases the stress on other spokes

I'm a Clyde at 230# and build my wheels 36h 4x for comfort and durability. This makes for a heavier wheel for the given hub/rim combo due to the greater number and slightly longer spokes but with good rims and hubs you can get some pretty bomb-proof wheels. That said, your choice of 32 or 36 spokes doesn't make nearly as much difference as quality components and a competent builder.

RocTurk

I didn't realize you are in GA. You may wanna also check CUSTOM HAND BUILT BICYCLE WHEELS Built By Professionals - Prowheelbuider.com they might even be closer to you than Boyd. Haven't purchased anything from them but they have good reputation. Emailed them while back for suggestions and they responded pretty quickly. If your budget is around 1K$, I'd ask their recommendation. Their catalog is huge and they carry high quality brands.

mrfreezesdefy3

Thanks I'll look into them . I talked with Boyds today they said they recommended the alloy Altamont 32 in back n 28 in front . They said that the to use the I think it was cx sapims hubs with cx spokes if I wrote it down right .. they said the used a larger nipple and each spoke was tensioned .from what I gathered a factory run wheel just is enough to get it out the door and not much else so as a clyde Boyd said that upgrading to a custom built wheel set would be better for me
They also said to change pads to prevent old metal that might be inpregnated in my old ones to cover the warranty on the new wheelset and they would put all my new tires and tube on it for me so I'm thinking we going to Greenville fri .but I'll look at the other link .Boyds service and warranty are hard to beat from what I've googled

RocTurk

I think that's a good decision. It'd be great if you can share your experience with them at some point. It's hard to find clyde rated aero wheels on the market.

mrfreezesdefy3

@RocTurk
This is what I think I'm going with


As mentioned here is what we discussed:

Altamont- Alloy

28/32 Spoke Count

Total Price:* $690

Tax:* $41.40

Total:* $731.40

Skewers and Rim strips included

Swisstop BXP brake pads:* $30


Come on up to Greenville and we will install the wheels on your bike at no charge.

You will need to bring tubes, tires, and cassette. We can take the cassette off your old wheel for you.

Let me know if you have any questions.

If you would like to move forward with this option please call me as soon as you are ready so we can make sure the wheelset is built and ready to go for you on Friday.

After 20 min on phone yesterday I feel comfortable with this
I only have 9 gears on my defy but they said they'd put a spacer in there I'll let you know of my experience

RocTurk

Sounds good.... I meant experience with the wheels too. Boyd customer service has good reviews under other forums too (road cycling, cx ,etc.).