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Modern rims crack at spoke holes
#1
Recently, I was in one of the local bike shops. Someone had brought a bike back to have the back wheel re-trued. There were actually cracks in the rim, originating from the spoke holes.

I have had the same problem with my bike.

In past decades you could buy a bike, and the wheels were strong. With modern rims, the aluminum is getting thinner and thinner. Now the rims crack.

With heavy riders, and people riding on rough tracks, rims may crack in a fairly short time. With lighter riders, they may take much longer to crack. They may not crack on bikes which are only ridden for short distances on rare occasions.

Shimano has had to have a huge recall for selling faulty cranks. I wonder if there will ever be repercussions for rim, or wheel, or bike manufacturers, over faulty wheels.

https://forums.bikeride.com/thread-8594.html.

The response everybody gives is, buy an expensive bike or expensive wheels. The wheels on many expensive bikes are the same, and will crack the same. Don't just buy any wheels, do your research and buy wheels that are stronger.

In the past, you could buy a cheap bike, and the wheels were strong. Bikes should not have parts designed to fail.

My suggestion to people wanting to buy a bike, is buy a used older bike. They are stronger.

   

   

   
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#2
Rim cracks are still mysterious to me.

I never had to deal with one yet, but I would imagine it's due to poor maintenance and truing schematic over years in most cases, rather than the material. When you take your wheel to bike shops to have them trued, often they will only true them lateral and will not true them radial. Overtime, this would cause the wheel to become crazy tension webbed. Where wheels will already have certain spokes with a little more tension than others—this becomes accentuated terribly—and the strain on that part of the rim will increase exponentially.

If you really wanted to narrow it down to quality, you would need to know the brand of the bike for a better idea of what the cost of production likely was (and thus, the range of quality in the materials used/purchased). I honestly don't find that top companies use any components at all that are low quality. The rims are always very strong, double walled, 6061 T6 aluminum. The larger the wheel, more prone it becomes to flex, because of the distance factor involved. Even so, it's not easy to bust a double wall high grade aluminum rim this way. One should always consider sabotage in these cases also, where a person vandalizes their own components in attempts to cash in on any warranty benefits.
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#3
(11-07-2023, 03:50 PM)ReapThaWhirlwind Wrote:  Rim cracks are still mysterious to me.

I never had to deal with one yet

How new are the bikes you ride? I have only experienced this with bikes that were new in the last couple of years. If you are riding older bikes, I would not expect rim cracks.

Not all rims are equal. There are many stronger rims. There are also many of weak rims.
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#4
(11-08-2023, 06:54 AM)ichitan Wrote:  
(11-07-2023, 03:50 PM)ReapThaWhirlwind Wrote:  Rim cracks are still mysterious to me.

I never had to deal with one yet

How new are the bikes you ride? I have only experienced this with bikes that were new in the last couple of years. If you are riding older bikes, I would not expect rim cracks.

Not all rims are equal. There are many stronger rims. There are also many of weak rims.

I rode Mongoose and Hyper big box bikes for years. They have general grade aluminium single wall rims. Never seen a crack, but saw quite a few broken spokes on the rear drive side wheel (from machine built under-tensioned spokes). I've had over tensioned wheels where indents were left in the spoke holes, but no signs of beginning to crack. I've built a dozen wheels on new rims. The metal is so strong and rigid from having no weathering. Older rims will still be good and usable, but the metal becomes more flexible as it ages and weathers; especially if it still has old spokes lacing it together. Today's manufacturing has become so good, cheap quality parts can only really be seen where metals are competing against one another; such as with tools or with threading. Even with today's manufacturing, steel screws can still strip out aluminum threads fairly easily.
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#5
If you look at the picture, which is zoomed in a long way, the spoke is 2 mm thick. Compare the thickness of the rim where it is cracked. How thick is it?

These rims are designed to fail.

   
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#6
It might also be helpful to consider that wheels built on machines use spokes that are longer than hand-built wheels.

I honestly have no idea how that works, but it does result in a crazy tension web eventually; where all the spokes will be tightened all the way to the nipple heads. Some will turn incredibly easy and some will be incredibly tight. That's very bad wheel schematics.

With spokes the proper length, the nipple will fail long before the rim ever could. It will pop from the threads from overtension.
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#7
Here are some videos on wheel assembling and truing machines.

https://forums.bikeride.com/thread-8683.html
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#8
I have put together a wheel using a stainless steel rim from a bike around 40 years old. The bike I got it from was rusty, and in the trash. The rims are still like new.

In the future, I plan to put together wheels with stainless steel rims for other bikes. These rims are really strong, and I expect they will never break.

https://forums.bikeride.com/thread-8529.html
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#9
Lighter rims are great but not for heavier riders... I think its as simple as that. There was a post a few months ago about carbon fiber rims which are super light but encountered the same issue with heavy riders. Sad
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#10
(02-29-2024, 07:54 PM)Talha Wrote:  Lighter rims are great but not for heavier riders... I think its as simple as that. There was a post a few months ago about carbon fiber rims which are super light but encountered the same issue with heavy riders.

You are right but.

A heavy rider may experience a failure in a fairly short time. A medium weight rider may experience the same issue after a longer time.

For example, a heavy rider might experience a failure in a month. A medium weight rider may experience a failure after two years. A light weight rider might experience a failure after ten years. Weak wheels are a problem.

I drop in on one of the local bike shops from time to time. He has riders who bought a bike two years ago, bring it in to have the rear wheel re-trued. He finds cracks in the rim, originating from the spoke holes. These are people who regularly cycle for exercise, so they ride their bike a fair bit. They are only medium weight.

As discussed previously, I put together a wheel using a stainless steel rim from a bike around 40 years old. The rim still looks brand new. It was from a ladies bike. In those days stainless steel rims did not break. I expect this rim to never fail, even with a heavy rider, even on rough tracks.

https://forums.bikeride.com/thread-8529.html
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#11
(02-29-2024, 07:54 PM)Talha Wrote:  Lighter rims are great but not for heavier riders... I think its as simple as that. There was a post a few months ago about carbon fiber rims which are super light but encountered the same issue with heavy riders. Sad
Lightweight rims are designed for racing and not general use even by average weight riders. Also, those lightweight rims are often used for a very short period of time and are not for training or everyday use. There are very few top level racers that weigh over 180 pounds; and those that are would have rims designed for their specific needs. Carbon rims (and bikes) are not designed for casual riders and I do not recommend them except when used for their specific purpose and within their designed limitations. Too many casual riders are getting high end equipment thinking it is for daily or rough conditions not realizing that they are buying equipment used for an entirely different level of riding for use by those who will have equipment replaced regularly at no cost.
Take care,
Jesper

"I am become Death, the destroyer of bicycles." NJS
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#12
(02-29-2024, 11:15 PM)Jesper Wrote:  
(02-29-2024, 07:54 PM)Talha Wrote:  Lighter rims are great but not for heavier riders... I think its as simple as that. There was a post a few months ago about carbon fiber rims which are super light but encountered the same issue with heavy riders. Sad
Lightweight rims are designed for racing and not general use even by average weight riders. Also, those lightweight rims are often used for a very short period of time and are not for training or everyday use. There are very few top level racers that weigh over 180 pounds; and those that are would have rims designed for their specific needs. Carbon rims (and bikes) are not designed for casual riders and I do not recommend them except when used for their specific purpose and within their designed limitations. Too many casual riders are getting high end equipment thinking it is for daily or rough conditions not realizing that they are buying equipment used for an entirely different level of riding for use by those who will have equipment replaced regularly at no cost.
true that! 100% correct
There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
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#13
(02-29-2024, 11:15 PM)Jesper Wrote:  Lightweight rims are designed for racing and not general use even by average weight riders. Also, those lightweight rims are often used for a very short period of time and are not for training or everyday use. There are very few top level racers that weigh over 180 pounds; and those that are would have rims designed for their specific needs. Carbon rims (and bikes) are not designed for casual riders and I do not recommend them except when used for their specific purpose and within their designed limitations. Too many casual riders are getting high end equipment thinking it is for daily or rough conditions not realizing that they are buying equipment used for an entirely different level of riding for use by those who will have equipment replaced regularly at no cost.

There are bikes being sold with poor quality rims, because they are less expensive.
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#14
In the future, expect to find bikes with broken wheels in the trash. Some people will buy a new bike and trash the old one. If you can come up with an inexpensive way of replacing broken wheels, you should be able to get bicycles worth repairing, without spending a lot of money.
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#15
(11-07-2023, 08:28 AM)ichitan Wrote:  Recently, I was in one of the local bike shops. Someone had brought a bike back to have the back wheel re-trued. There were actually cracks in the rim, originating from the spoke holes.

I have had the same problem with my bike.

In past decades you could buy a bike, and the wheels were strong. With modern rims, the aluminum is getting thinner and thinner. Now the rims crack.

With heavy riders, and people riding on rough tracks, rims may crack in a fairly short time. With lighter riders, they may take much longer to crack. They may not crack on bikes which are only ridden for short distances on rare occasions.

Shimano has had to have a huge recall for selling faulty cranks. I wonder if there will ever be repercussions for rim, or wheel, or bike manufacturers, over faulty wheels.

https://forums.bikeride.com/thread-8594.html.

The response everybody gives is, buy an expensive bike or expensive wheels. The wheels on many expensive bikes are the same, and will crack the same. Don't just buy any wheels, do your research and buy wheels that are stronger.

In the past, you could buy a cheap bike, and the wheels were strong. Bikes should not have parts designed to fail.

My suggestion to people wanting to buy a bike, is buy a used older bike. They are stronger.

This was normal for Ksyriums for many years. You could expect your Ksyriums to last about one year before cracks started forming at the spoke holes. They seem to have overcome that now. It was simply caused from the rim being made too thin and the metal being so hard that it would harden from the pressures of riding.

All it would have taken to prevent this was to have very slightly increased to rim thickness near the spoke holes and that is what I believed they did.
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#16
Maybe, note I said maybe, rims are cracking more due to using all recycled aluminum these days instead of virgin aluminum like they did 30-plus years ago??

I say that because I'm into vinyl records, what does that have to do with bikes you scream? Welp, years ago when vinyl was the only medium they used virgin vinyl, while they did scratch and wear it took more to do so than modern vinyl records that are using recycled vinyl, the new records if you breathe on them wrong they get scratched.

So maybe using recycled aluminum is not as hardy as the virgin aluminum was so they're cracking more.

You would think that melting down recycled AL it would be the same as virgin AL, but maybe that process of melting at least twice does something to the strength of the AL, or maybe the aluminum being used might have been recycled many times before being used to make a rim.

Of course, Americans have been gaining weight over the years, but I still have that weird itch in my one remaining brain cell about whether or not recycled aluminum is weaker and or more brittle than using virgin AL.

Just a stupid thought.
Wag more, bark less
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#17
(04-13-2024, 09:32 PM)froze Wrote:  Maybe, note I said maybe, rims are cracking more due to using all recycled aluminum these days instead of virgin aluminum like they did 30-plus years ago??
Just a stupid thought.

Not a stupid thought unless you are implying that I had one too.
I pondered this due to some parts we were using at an industrial level and if using a supposedly "virgin" part made from ore as opposed to a part made from recycled material changed its properties to any great degree. I spoke with a metallurgist and the simple answer was "no"; the complicated answer was "yes" (due to processing, impurities, alloying, etc.), but not really relating to the properties of the base metals themselves. Simply stated, metal alloys are made for specific properties, and regardless of whether it was derived from ore or recycled material that end product must still meet the properties that the manufacturer requires for any given application. Alloys undergo testing, as well as testing the finished products they are used for.
Take care,
Jesper

"I am become Death, the destroyer of bicycles." NJS
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