Olaf330

So for the third time this month, I've snapped a rear spoke. It's always the spoke connected at the drive side, right at the spoke head bend. The rims are Alexrims ID19, 32 hole.

I've had the spokes replaced for free where the bike was purchased at Performance Bike. They mentioned after the third one they'll look into a warranty replacement. They feel it may be a defective rim or hub. I dunno.

Will it matter though? I'm 250 lbs. Is this wheel too weak for me? Do I need to look into something substantially stronger? I've been riding this bike since I was a heftier 280 lbs. and haven't had any problems until recently.

mrrabbit 

Until they:

1. Rebuild the wheel with all new spokes again...
2. Show you the tension meter reading on the drive side...
3. And convert on the chart the reading confirming an average of 110kgf for that side of the wheel...

...they can't make any claims as to hub, rim or spokes...

Undertensiong of spokes is typically the #1 cause of broken spokes at the elbow of the head....

Your current spokes are probably fatigued already - so the rebuild needs to be with all new spokes.

=8-)

Drew Eckhardt 

The wheel was assembled sub-optimally. The parts should be good enough.

Spokes fail due to fatigue when the wheel was not properly stress relieved thus leaving high-stress regions near the elastic limit in the elbows from when they were manufactured. Low tension can also reduce the number of stress cycles a wheel will survive.

A replacement wheel built the same way will have the same problems. One which has sufficient uniform tension and is stress-relieved (and not starting with fatigued spokes) will not.

You get to sufficient tension by increasing it until the wheel deforms in waves when you stress-relieve after which you back-off half a turn and re-true. You can use a tension gauge. You can go for the right musical pitch.

You stress relieve by wearing a pair of work gloves and squeezing near-parallel pairs of spokes as hard as you can (except with very light or radially-laced rims). You can put an old left crank or brass drift in the spokes where they cross and twist them around each other.

Or you can delegate all this to a competent wheel builder.

davidad

At your weight a 36 spoke wheel is an excellent idea. It should be built up with double butted spokes and tensioned to at least 110kg.
Ask your shop how much tension they are puting on the spokes. They should be able to give a number.

Olaf330

Thanks for all the ideas and suggestions. If I can get out of work at a decent time today I plan on going to the bike shop and seeing what they'll do. I'll follow up with their results.

What puzzles me is that i've been riding this bike since March and have had no issues for nearly two months. All of a sudden the spokes are snapping. I'm lighter than I was when I initially started riding! And it's not like I beat on the bike at all. Mostly riding around the neighborhoods.

ironwood

There is something called metal fatigue. Perhaps the wheel was not tensioned properly at first. Velocity makes an asymetrical rim, which makes it possible to reduce the difference in tension between the drive and non-drive spokes.

mrrabbit 

The root of the problem:

Your average bike shop, sad to say, especially moreso chain shops, do not spend the 20 minutes they are supposed to spend finishing up the wheels that come with your entry and mid-range bikes. They just slap the bike together - a tad on bike true here and there - and out the door you go.

It only takes a few weeks to a few months for cheap spokes to run the fatigue gamut...might take high quality spokes considerably longer...but they tool will fall victim.

Most entry-bike to mid-range bike factory wheels typically show up in the 70-80 kgf range - which is at best "hold together" tension...and even an occasional one will loosen to a limp spaghetti state...

=8-)

Olaf330

Mrrabbit, the bike was a $700 Fuji so definitely nowhere near top end. It's most likely true what you say then.

I swung by the store tonight with rear wheel in hand. I mentioned the whole "three broken spokes and we'll look into a replacement" thing, but naturally, the guy who told me that is no longer employed there. So instead I had to leave my wheel behind and the guy who runs the repair department will look over it and call me in the morning with his thoughts and opinions on the matter.

Naturally I'm hoping they'll replace all the spokes and tension it all up right. They've done the prior single spoke replacements at no charge, but I doubt they'd do a rebuild for free. It would be nice though.

That being said, I'm getting tired of driving 30 minutes to get a spoke replaced. It may be something I can eventually learn to do but I'm not too keen on the idea of playing with spokes. Especially seeing how easy it is for the wheel to be... disagreeable. But something is odd and I hope it's just goofy tension.

I browsed around the forums about and read up on those Velocity Deep V's and went to their site. It seems you can't order directly from them; only through your bike shop. Performance Bike doesn't carry the brand. Can anyone recommend some other tough wheelsets I should look at, in case my current wheels decide to give out again?

mrrabbit 

Brand Name: Alex, Mavic, Sun, KinLin...
Double Wall
Single Eyelets, Double Eyelets is even better...

Weight don't be afraid to go 500-525g weight-wise...for a little beefiness...

=8-)

furballi

The hub should be okay as long as it is a 32h or 36h item. Mavic CXP22 or Sun CR-18 rim with 2.0mm DT Champion spokes/nipples at 3x should yield a very strong wheel if properly built. 250 lbs is a lot of mass for the average non-custom built wheel.

Try to spread apart the two spokes (cassette side) at their crossing with one hand. You should encounter very stiff resistance before the spokes lose contact if the wheel is properly tensioned. This technique will not work if the wheel is radially laced.

I personally would not let this shop rebuild a new wheel since they did not properly set you up with the right set of wheels. Performance is usually located in a major city so you shouldn't have any problem finding a good wheelsmith.

https://www.treefortbikes.com/product...R-18-700c.html

https://www.chainreactioncycles.com/M...?ModelID=17150

mrrabbit 

Mavic A719 is one rim I really like...others here do too...

=8-)

vredstein

This really is the root of so many problems. Regardless of how the factory machine built the wheel, the person who builds the boxed bike has the opportunity to make it right. In many cases, the owner or manager only sees the bike as a number with a dollar sign in front of it. That number has a corresponding number on a clock face. The corresponding number on the clockface is the maximum amount of time/attention the owner/manager will allot for that bike. They see no problem if the mechanic never lays his hands on the rear wheel's quick release. Somehow, the owner/manager actually starts to believe these mechanically irrelevant bean counting numbers actually do represent the amount of time needed to get the bike working properly, and remaining in proper working order. So a new mechanic starts, these substandards are ingrained into his work ethic.
If owners/managers viewed that bike as a potential form of transportation for their own mother, rather than just a cost/labor ratio to uphold, the customer/shop relationship would improve 100%.

Wanderer

If they are doing a complete rebuild, which, at this stage, should be done - it should include rim, spokes, and hub, all NEW.

Ask for a 36 spoke version, and be willing to pay a sligh difference in cost for it - it will be worth it. It shouldn't be any more than 5 or 10 bucks MAX.

When you get it, take it to a real bike shop, one that tensions spokes with a meter, and ask them to tension and true it.

It should then last almost forever.

Performance may be a good place to buy stuff, but usually a bad place to have stuff repaired.

RaleighComp

In addition to this I take the knob ball end of a large Sears Craftsman screwdriver handle and jam it into the triangular intersections of crossing spokes from both above and below. I think I picked that tip up from Jobst Brandt's book, but I don't remember.

Olaf330

Here's an update. I picked up the wheel today. It was not rebuilt and would have taken 2 weeks of them dealing with Fuji to get a warranty replacement. I asked them to replace the spoke and I would just come and get it. No charge.

I used a Park Tool tension meter on every single spoke and wrote down the numbers. According to Sheldon Brown's site, every spoke should have the same amount of tension, correct? Except for the rear drive/non drive side. But if so, my wheels definitely do not.

2.0mm steel spokes, according to the little round gauge that came with meter. Values were converted with the chart that came with it too.
Rear/Drive Side: Average of 68 KgF, high of 137 KgF, low of 51 KgF
Rear/Non Drive: Average of 56 KgF, high of 85 KgF, low was not on the scale, 15 on the meter.
Front/Drive Side: Average of 62 KgF, high of 95 KgF, low was not on the scale, also 15 on the meter.
Front/Non Drive: Average of 68 KgF, high of 85 KgF, low of 62 KgF

I tried to keep the meter centered between the rim and hub. I hope that was right. If you're really curious I can list every spoke number but I'll spare you the mundane details. But mrrabbit, you say there should be a 110 KgF force on the rear drive side? Clearly this isn't the case here.

mrrabbit 

Your drive side readings should have been along the lines of 95, 107, 121 with a lot of converted ESTIMATED readings falling in between. Usually the worst spokes on the extremes will be the two spokes (non-drive and drive) by the joint and those two often fall outside the noted 3 points above.

Whoever replaced the spoke and supposedly "trued" the wheel quite frankly is not up to the job.

=8-)

furballi

Wheel is not properly tensioned. Wait two weeks for a new wheel from Fuji, then check the tension. If not appropriate, then you need to give this wheel to a good wheelsmith and let this person re-tension the wheel.

I prefer to keep the minimum tension north of 130 KgF for a heavy rider. The spoke tension will decrease at least 5-10% after the first 400 miles. I don't use a gauge...just years of experience in the hobby.

Olaf330

I have access to a truing stand and spoke wrenches. If I were to attempt to get the spokes more evenly matched with higher tension, would that solve the issue or introduce new issues?

I was curious where the 110 KgF number came from and it seems like the Alexrims website mention the same, albeit in very poorly worded english. Does the front rim need this same amount? I've never broken a spoke up there and the rim doesn't wobble at all, despite the fluctuating tension numbers listed above.

And on the rear, is it 110 on one side? What about the other side?

I ask because this is all a good opportunity to learn. There are a few bike shops in my area but it's hard to walk in and ask if they are a competent wheel builder. 9/10 would say they are.

mrrabbit 

Ans1: When the drive sides averages 110 kgf AND the wheels is true AND the wheel is dished...after a final stress relief cycle...

...you're done.


Ans2:

Most modern day alloy rims of basic box, semi-box and aero design are rated for 100-110kgf. Some can actually take more - but isn't covered by warranty. Some tensionmeters such as Wheelsmith's include the caveat not to have an average that exceeds 120 kgf. Some but not all paired spoke rims are rated for 120-130 kgf. Many carbon rims regardless of lacing arrangement have a 130 kgf average ceiling while I know of one that has a max of 80 kgf.

Be aware that some manus purposely set the limit low on their alloy rims to preempt warranty submission - even though many of us wheel builders know what their rims can really handle. I think it's dishonest - but then again - manus have a right to set their terms. Customers have a right to buy or not to buy. It's as simple as that...


=8-)

Olaf330

Excellent. A big thank you to you and and all the others that have helped me out. I'll give it a try and see if I can tension the spokes up more and balance it all out.

If I screw it all up I'll use it as a learning experience and buy myself some nicer, hand-built units!

mrrabbit 

Your welcome...

Keep in mind that your spokes may have already fatiqued...which is why myself and others suggested a rebuild with new spokes....

=8-)

Olaf330

Yeah, I just hope they aren't fatigued too terribly. But I did have a go at working on the tension.

On the rear, drive side average is now 107, non-drive side is now 85. It's getting closer! It's a big balancing act to keep tension up while trying to keep the wheel true.

mrrabbit 

Yeah...that's the wheel building life. More stress induced as you get closer and closer...more stress relieving cycles to settle it down and hoping each time that it stayed true. It's even more painful when it's a wheel with an extreme offset to one side...

Keep your head off to one side when stress relieving - never know that a spoke might snap - especially since you might have fatiqued spokes.

Remember to keep the wheel dished...the 85 on the nds seems to indicate that your rim might be a little off dish...just a suggestion.

Take your time...107 is pretty good...couple more "clicks" and you're done after a final settled stress relief.

Don't have to be perfect - most of us here prefer to actually ride.

Question: How are the two spokes near the joint? Are they in line (consistent) with their buddies on their sides of the wheel - or out of line?

In-line = quality joint. Out-of-line = bad joint in most cases.


=8-)