Reasons for wheel failures

Nobody
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Re: Reasons for wheel failures

Postby Nobody » Thu May 23, 2013 2:14 pm

Duck! wrote:Gluing the nipples on is a pretty poor solution to a badly built wheel.
Sheldon disagrees with you.
Sheldon Brown wrote:The left-side spokes will be loose enough that it will not be hard to turn the nipples even dry, and if you grease them they may loosen up of their own accord on the road. In fact, it is often a good idea to use a thread adhesive such as Wheelsmith Spoke Prep on the left-side spokes to make sure they stay put. This is only necessary on a rim with recessed spoke holes.
Under "Preparation" in link below.
http://www.sheldonbrown.com/wheelbuild.html" onclick="window.open(this.href);return false;

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Re: Reasons for wheel failures

Postby biker jk » Thu May 23, 2013 3:05 pm

Nobody wrote:
Duck! wrote:Gluing the nipples on is a pretty poor solution to a badly built wheel.
Sheldon disagrees with you.
Sheldon Brown wrote:The left-side spokes will be loose enough that it will not be hard to turn the nipples even dry, and if you grease them they may loosen up of their own accord on the road. In fact, it is often a good idea to use a thread adhesive such as Wheelsmith Spoke Prep on the left-side spokes to make sure they stay put. This is only necessary on a rim with recessed spoke holes.
Under "Preparation" in link below.
http://www.sheldonbrown.com/wheelbuild.html" onclick="window.open(this.href);return false;
Again, if the wheel is built with sufficient tension in the non-drive side spokes then there's no need for thread adhesives. Yes I do know that the non-drive side spokes will be at much lower tension than the drive side but too low is a wheel building error.

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Re: Reasons for wheel failures

Postby Nobody » Tue May 28, 2013 10:24 am

biker jk wrote:Again, if the wheel is built with sufficient tension in the non-drive side spokes then there's no need for thread adhesives. Yes I do know that the non-drive side spokes will be at much lower tension than the drive side but too low is a wheel building error.
But the tension on the non-drive side spokes is defined by the rim manufacturer's maximum spoke tension recommendation. Unless you are going to exceed this, then you are looking at approx 65% of that recommendation. In the case of the Mavic A719, that's only 105-110 Kgf. So that makes ~72 Kgf. Not a lot of pressure, so you wouldn't want to be lubricating the spokes or nipple seats. The last build of these wheels (317D/A719, disk on front) did unwind on the non-drive side over 3 years and I had to wind them back up. FWIW I haven't placed any thread locker on the new build yet and I'll see how they go. If you want to go significantly past the manufacturer's recommendations I'm sure you could get them tight enough, but I don't want to do that yet.

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Re: Reasons for wheel failures (movement at the hub holes?)

Postby iantag » Wed Jun 19, 2013 11:49 pm

I'm a heavy rider ~120kg and build my own wheels ( DT competition and/or Alpine III's). I generally don't break spokes but recently while riding one of the GVBR's I had about 3 drive side "pulling" spokes lose their heads. ( of the 6 spokes I've broken over 30-years all have been rear drive pulling spokes) As luck would have it I carried extra spokes and simply replaced the offending one - and for good measure the immediate neighbors. The bike mechanics on the ride (both Kiwi's) both swore that brass spoke washers under the head would have prevented the breakage. This was news to me so I did some research to discover that the use of spoke washers (at the hub) is up there with religion and politics as a way of generating emotive responses. The pro argument goes like this: 14 gauge spokes measure 2.0mm and most hubs have 2.35 mm holes. Hence with each revolution their is the possibility of some movement & therefore repetitive stress. Alpine III's are 13g or 2.3mm and besides being thicker at the hub - better "fill" the hole resulting in less chance for movement. Brass washers deform under tension and "fill" into the hole creating a snug fit ( you can get different sized washers for 14g and 13g spokes). Anyway - long story - I've now built my latest sets of wheels with washers - which means I've bought into the "pro" side. I also (now) use a tension meter - as I think while true - some of my past wheels had non-uniform tension - which only makes matters worse. So I guess I'm a spoke washer believer ( for now). (I've also built with O/C rims - but that's another story)

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Re: Reasons for wheel failures

Postby foo on patrol » Sun Jun 30, 2013 7:21 am

Reading through this thread makes me think that todays gear, is nowhere near as good in the reliability stakes as it was back in the 70s. :?

This is one set of rims I used back then and ran 150psi in them and stayed true until I was involved in a high speed crash on the track. :(

http://www.classiclightweights.co.uk/co ... -rims.html" onclick="window.open(this.href);return false;

And these where my Road Race Rims, Ambrosio Montreal 36x32. Three seasons of racing and still true.

http://velobase.com/ViewComponent.aspx? ... 159b67f729" onclick="window.open(this.href);return false;

So my thoughts are. The quality of material is less and is stressed to the maximum for so called performance and nowhere near as reliable. The spokes on my wheels where double butted stainless 12g from memory on low flange hubs for the road and high flange for the track.

Summing up. Buy a set of stiff rims and put them to a set of hubs that have very good rolling properties, because one thing I have noticed is some of the hubs these days don't roll anywhere near as smooth as they did from the 70/80s, even the cheap ones from that period. Living in the past maybe but our reliability back the, was far superior. :wink:

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Re: Reasons for wheel failures

Postby biker jk » Sun Jun 30, 2013 8:54 am

foo on patrol wrote:Reading through this thread makes me think that todays gear, is nowhere near as good in the reliability stakes as it was back in the 70s. :?

This is one set of rims I used back then and ran 150psi in them and stayed true until I was involved in a high speed crash on the track. :(

http://www.classiclightweights.co.uk/co ... -rims.html" onclick="window.open(this.href);return false;

And these where my Road Race Rims, Ambrosio Montreal 36x32. Three seasons of racing and still true.

http://velobase.com/ViewComponent.aspx? ... 159b67f729" onclick="window.open(this.href);return false;

So my thoughts are. The quality of material is less and is stressed to the maximum for so called performance and nowhere near as reliable. The spokes on my wheels where double butted stainless 12g from memory on low flange hubs for the road and high flange for the track.

Summing up. Buy a set of stiff rims and put them to a set of hubs that have very good rolling properties, because one thing I have noticed is some of the hubs these days don't roll anywhere near as smooth as they did from the 70/80s, even the cheap ones from that period. Living in the past maybe but our reliability back the, was far superior. :wink:

Foo
In the "old" days the box section rims were laced 36 or 32 spokes so built a strong wheel. Indeed, the rims were often much lighter than models now. There's been a move to low spoke count wheels which if combined with shallow rims doesn't build as strong a wheel.

Still, I do note the first comment on the Ambrosio Montreal,

"A very light weight vintage tubular rim but these had numerous bad runs which led to spokes pulling through.".

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foo on patrol
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Re: Reasons for wheel failures

Postby foo on patrol » Sun Jun 30, 2013 9:00 am

Yeah I saw that also. I must have been lucky. Keith Reynolds built my wheels in the day and never ever had a problem with his builds. :D

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Re: Reasons for wheel failures

Postby Thrilloilogy » Sun Sep 08, 2013 9:58 pm

Just noticed on my Alex Rims that the rim has a small crack less than a cm in length where the rim joins the braking part of the rim. It's not sticking out much - maybe less than a mm.

Is the wheel safe to continue to use; or should I be getting it fixed?

Knowing me, I'd just upgrade from the base rim if it needed to be repaired; and the wife wouldn't be happy!

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Re: Reasons for wheel failures

Postby ironhanglider » Mon Sep 09, 2013 9:42 pm

Thrilloilogy wrote:Just noticed on my Alex Rims that the rim has a small crack less than a cm in length where the rim joins the braking part of the rim. It's not sticking out much - maybe less than a mm.

Is the wheel safe to continue to use; or should I be getting it fixed?

Knowing me, I'd just upgrade from the base rim if it needed to be repaired; and the wife wouldn't be happy!
Hard to advise without seeing it. I have seen catastrophic rim failure once where about 20cm of sidewall broke away from the 'floor' of the rim. In that case it had been weakened by wear.

I have had a rim of my own split in the middle of the sidewall and puncture the tube. I was able to put a bit of cardboard over it to protect the spare, and rode it home. I have seen other rims with multiple cracks around spoke holes that were still straight.

Either way a crack is the end of the rim, you can take your own chances. As for what to do now, you can either get a new rim (and probably spokes), or a new wheel. If you can do it yourself then rim replacement is an option. If you can't then a new wheel is likely to be cheaper.

Cheers,

Cameron

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Re: Reasons for wheel failures

Postby Velo13 » Wed Sep 18, 2013 10:46 am

Thrilloilogy wrote:Just noticed on my Alex Rims that the rim has a small crack less than a cm in length where the rim joins the braking part of the rim. It's not sticking out much - maybe less than a mm.

Is the wheel safe to continue to use; or should I be getting it fixed?
No, and yes. Don't risk it.

Cheap insurance, and you'll have a nice rebuilt/new wheel underneath you.

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Re: Reasons for wheel failures (movement at the hub holes?)

Postby fixie » Mon Nov 11, 2013 8:35 pm

iantag wrote:I'm a heavy rider ~120kg and build my own wheels ( DT competition and/or Alpine III's). I generally don't break spokes but recently while riding one of the GVBR's I had about 3 drive side "pulling" spokes lose their heads. ( of the 6 spokes I've broken over 30-years all have been rear drive pulling spokes) As luck would have it I carried extra spokes and simply replaced the offending one - and for good measure the immediate neighbors. The bike mechanics on the ride (both Kiwi's) both swore that brass spoke washers under the head would have prevented the breakage. This was news to me so I did some research to discover that the use of spoke washers (at the hub) is up there with religion and politics as a way of generating emotive responses. The pro argument goes like this: 14 gauge spokes measure 2.0mm and most hubs have 2.35 mm holes. Hence with each revolution their is the possibility of some movement & therefore repetitive stress. Alpine III's are 13g or 2.3mm and besides being thicker at the hub - better "fill" the hole resulting in less chance for movement. Brass washers deform under tension and "fill" into the hole creating a snug fit ( you can get different sized washers for 14g and 13g spokes). Anyway - long story - I've now built my latest sets of wheels with washers - which means I've bought into the "pro" side. I also (now) use a tension meter - as I think while true - some of my past wheels had non-uniform tension - which only makes matters worse. So I guess I'm a spoke washer believer ( for now). (I've also built with O/C rims - but that's another story)
Spoke manufacturers do not all have the same dimension for the distance between the head of the spoke and the line of the spoke. They vary from manufacturer to manufacturer. Also, hub manufacturers do not all use the same dimension for the thickness of the flange on the hub where the spokes insert. Sometimes with a wide bend spoke and a thin flange the space between the line of the spoke and the flange is significant and this introduces a real bending strain into the J bend part of the spoke which can contribute to spoke failure. To reduce or eliminate this, the cheap practical method is to put a spacing washer under the head. This will ensure that the spoke tension to the flange is as direct as possible and that the spoke at the bend is as much in a shear stress rather than a bending stress as possible.

If you have ever tried to lace a wheel with an old steel hub or a Sturmey Archer three speed with a steel shell you will realise how thin a hub flange can be and how large a gap there will be if you do not use a spoke washer under the head. Often you can get away with it because with steel rims, they are so stiff, the spoke tension variation on rotation is minimised and even a poorly built wheel will survive, but with modern alloy rims of variable section and construction you will not. Mind you, you can also revert to galvanised spokes instead of the luxurious Stainless Steel ones regularly available today and find that the J bend dimension is so small that they will not fit in a modern alloy hub. But they would be very good in a steel hub.

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Re: Reasons for wheel failures (movement at the hub holes?)

Postby Velo13 » Wed Nov 13, 2013 1:40 pm

iantag wrote:I'm a heavy rider ~120kg and build my own wheels ( DT competition and/or Alpine III's). I generally don't break spokes but recently while riding one of the GVBR's I had about 3 drive side "pulling" spokes lose their heads. ( of the 6 spokes I've broken over 30-years all have been rear drive pulling spokes) As luck would have it I carried extra spokes and simply replaced the offending one - and for good measure the immediate neighbors. The bike mechanics on the ride (both Kiwi's) both swore that brass spoke washers under the head would have prevented the breakage. This was news to me so I did some research to discover that the use of spoke washers (at the hub) is up there with religion and politics as a way of generating emotive responses. The pro argument goes like this: 14 gauge spokes measure 2.0mm and most hubs have 2.35 mm holes. Hence with each revolution their is the possibility of some movement & therefore repetitive stress. Alpine III's are 13g or 2.3mm and besides being thicker at the hub - better "fill" the hole resulting in less chance for movement. Brass washers deform under tension and "fill" into the hole creating a snug fit ( you can get different sized washers for 14g and 13g spokes). Anyway - long story - I've now built my latest sets of wheels with washers - which means I've bought into the "pro" side. I also (now) use a tension meter - as I think while true - some of my past wheels had non-uniform tension - which only makes matters worse. So I guess I'm a spoke washer believer ( for now). (I've also built with O/C rims - but that's another story)
I am not sure if it is quite as contentious as religion and politics! However what I am about to say is!

You may be surprised how many bike shops/mechanics just don't build enough wheels to have seen this issue (and the need for spoke washers) or the outcomes of not using them (when they should have been used). As a result, they just lace the wheel up, tension it and hand it over to the customer. I know that I didn't even know of the existance of spoke washers in my first few years building wheels (back in the last century .... now I feel old) - and I would have built a couple of hundred wheels in that time.

I always use spoke washers in two different circumstances, and potentially in a third (the last one).

1. The hub flange is very thin compared to the length of the J-bend of the spoke - in which case the J-bend is not fully supported at its "bend", and pulls out of the hub hole and is bent straighter/stretched as the wheel is tensioned. This will result in early failure of the bend.
2. The holes are drilled >0.2mm larger than the spoke guage, in which case the J-bend straightens within the hub flange as the wheel is tensioned. This will result in early failure of the spoke head (most usually).
3. Reuse of hubs with very worn/grooved flanges and/or hole elongation. Washers may be used to get a nice tight fit, often after some filing/cleanup of the hub is done.
fixie wrote:Also, hub manufacturers do not all use the same dimension for the thickness of the flange on the hub where the spokes insert. Sometimes with a wide bend spoke and a thin flange the space between the line of the spoke and the flange is significant and this introduces a real bending strain into the J bend part of the spoke which can contribute to spoke failure. To reduce or eliminate this, the cheap practical method is to put a spacing washer under the head. This will ensure that the spoke tension to the flange is as direct as possible and that the spoke at the bend is as much in a shear stress rather than a bending stress as possible.
Eloquently said. A common issue with some of the ultralight hubs being produced these days in Taiwan. Not an issue if addressed when the wheel is built.

Most high quality maufacturers (think White Industries, Project 321, DT Swiss, Shimano, Campag) have nice thick flanges.
fixie wrote:If you have ever tried to lace a wheel with an old steel hub or a Sturmey Archer three speed with a steel shell you will realise how thin a hub flange can be and how large a gap there will be if you do not use a spoke washer under the head. Often you can get away with it because with steel rims, they are so stiff, the spoke tension variation on rotation is minimised and even a poorly built wheel will survive, but with modern alloy rims of variable section and construction you will not.
On a similar vein, the radial stiffness of quality carbon rims means that terribly uneven spoke tension can be hidden for quite some time. I have seen the highest quality carbon from the US and Taiwan, built with appalling and uneven tensions, but still quite rideable. They will present reliability problems over time - often pulling spokes at the rim.

That said, I have also seen some beautifully built factory carbon wheelsets. On a well constructed carbon rim, one can achieve impressively even spoke tensions.

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Re: Reasons for wheel failures

Postby Crawf » Wed Nov 13, 2013 4:07 pm

Re washers - what do you use? Something bike specific, or are we talking ss washers from the hardware store, what spec/measurements?

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Re: Reasons for wheel failures

Postby Velo13 » Thu Nov 14, 2013 12:45 pm

Sapim brass washers. Try asking for those a bike shop!

Not sure on the measurement, but any brass (sufficiently pliable and inert) washer of ID about 2.3-2.5mm and OD just a bit larger than the spoke head would work fine on a 14g spoke (ie 2.0mm at the butted ends).

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Re: Reasons for wheel failures

Postby australiantourer » Sat Apr 05, 2014 3:25 pm

ironhanglider wrote:
bardygrub wrote::shock: Well, the second replacement wheel has folded under the pressure. Spokes coming loose and all that again even after locctite. I have a meeting with my lbs on Thursday were we will sit down and work out what type of wheels we will be replacing the mavics with.

My LBS is prepared to give me the retail price of the Mavic Aksiums off the new set of wheels :D :shock: which i think is really good of them.

Now i know that there has already been input on this thread and others, but would be keen to hear other riders(95kg+) opinions again on what wheels they ride with.

I am happy to spend around the $500.00 mark of my own cash + the 300$ of the return of my current wheels. so a budget of $800.00 ish.

Cheers
Three cheers for a good LBS, they sound like they try to look after you. The loctite was certainly worth a try IMO but clearly you ride 'heavy'. Wider rims are becoming popular for aero reasons but they also permit wider tyres which amongst other attributes look after the rims better. Either deeper rims or more spokes will give you a stronger wheel and both will certainly do so, but do you really want tandem strength wheels? They come at the cost of more metal whether that is a bit more steel or a lot more aluminium. I've just built some tandem race wheels with 23mm wide rims that are only slightly deeper than yours at 25mm, but they do have 40 spokes each. They come in at 2100g for the pair (without discs), I haven't calculated what they would weigh with lighter spokes but under 2kg is easily doable since 40 spokes with nipples came to 300g for these.

30mm deep rims are typically about 520g (in 19mm) they are commonly used on tandems with 32 spoke wheels (although the wider rear hub allows for less severe dishing which allows stronger wheels). This is seen by conservative tandem folk as being unnecessarily minimalist and only for lightweight teams if that puts you in the picture. These would be the most conservative combination for you. You could probably build similar rims with 24 spokes rear and 20 front and be fine.

As for what people have I'd suggest that what anyone has is often more by accident than design. What probably matters it what they would choose next. For example I am 105kg but I tend to ride 'light'. Somehow I'm not a wheel breaker and I can get away with combinations that I wouldn't recommend for others my size. (probably something to do with my lack of power). On my single bikes I typically have 32 spoke shallow rims, but I also have a pair of 50mm deep plastic ones with 20/24 spokes and one pair of old Shimano wheels with hardly any spokes which are under lots of tension. In contrast I also have track wheels that have High flange hubs, 36 spokes and Deep V rims. Not very light but they are very strong. I did once finish a race despite another rider unkindly breaking 4 consecutive left side spokes on my front wheel with 2 laps to go. 8) It wasn't stable enough to sprint on though. :x I also have 32 spoke wheels on my tandem but they have 45mm deep rims (which weigh 880g). Fortunately they seem to be holding up for the riding I do which has my 18kg 3year old as a stoker midweek and my 95kg regular race stoker on weekends.

For commuting wheels for me I'd probably build the Deep V equivalent wheels in 32 spokes, since I have no interest in the cutting edge of performance anymore and that is probably a cost-effective combination.
see View item for example, or View item, but I'd be guided by my hub choice (and 32 F&R are still the most commonly available).

I'd probably also race on them too, but if I were chasing performance I'd go down the plastic wheels route again, (and almost certainly tubulars).

YMMV

Cheers,

Cameron
This conversation is more than a year old, but I'll dive in here anyway. I recently replaced the rear wheel of my early 1990s Tandemania because the freewheel cogs had worn out -- it now runs a freehub. The lbs offered a 36 hole double-walled rim (Alexrims DM20), assuring me that it would be far stronger than the 40 hole single skin is was replacing. I have just returned from a 3 day ride, which included some bumpy gravel roads. I was surprised to note that most of the spokes are looser than I would like, especially compared to the front wheel (still running the original 40h). In fact the nipple on one spoke was finger loose. The rim is still running true, so I am thinking carefully before I start to retension all spokes. (I have straightened wheels in the past, so I do understand the process).

My stoker and I are both lightweights (total 115 kg), and we don't ride powerfully (that could threaten the marriage!) Luggage probably weighed less than 20 kg. We approached the corrugations very gently. The tyres are 26 inch x 35 mm. What do people think -- is the new wheel up to the task? Do alarm bells start going off? I do feel a considerable sense of responsibility about this, and tandem riding is new to me (unlike solo touring).

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Re: Reasons for wheel failures

Postby ironhanglider » Sun Apr 06, 2014 2:29 pm

That is very disappointing.

I couldn't find DM20s on the Alexrims website but did see DM18 and DM22 so I presume that DM20s are a low profile double walled (double floored?) rim like them. I'm no expert but I'd expect the rim itself to be a bit stronger than a single walled rim but not as strong as one that has a deeper profile. The question is whether that makes up for the loss of 4 spokes. I'd have thought so, but your experience suggests otherwise.

Whilst your total load is very light for a tandem (160kg +/- 5kg), it is still very heavy by single bike standards. Does the Tandemania (KHS or Apollo?) have 135mm spacing at the back? It does sound as if the lbs grabbed the nearest cheap MTB wheel off the shelf. It might be the case that they have sold you a wheel that is not 'fit for purpose' important words for a claim under statutory warranty.

First off since it is new, I'd be taking it back to the shop and showing it to them. You should be expecting a wheel that could stand up to what you have done here. They are the ones who should be feeling a sense of responsibility about this, particularly if they were recommending this wheel. BTW normally Id say that replacing a freewheel with a freehub is a good move for a tandem. Screw on clusters are easy to buy, easy to fit, but eye-poppingly difficult to remove from a tandem wheel, as well as being more prone to broken axles.

It could easily be the case that the spokes were simply not tight enough from the factory, so are losing tension under load which causes the nipples to undo. If you read this thread from the beginning you'll find that this is a common enough theme and there are a few possible solutions.

The shop's options include:
They might replace the wheel, since the cost of labour to rebuild will reduce any profit they made from the wheel in the first place. If so it would be worth paying a bit more for one with a deeper rim for peace of mind.
They might just tighten up the loose spokes and true the wheel in the space of a few minutes, (which would all but guarantee a return visit in a little while).
They might re-build the wheel with more tension in the spokes overall, which may be enough by itself, but they might also apply a thread-locker. (Of course too much tension will cause the rim to fail prematurely but that may be some time off)
They might re-build the wheel with thinner/stretchier spokes. These lose less tension under load. (This would be an expensive option and only likely if sourcing other parts was too difficult.)

Back to the original question, the description of the wheel alone doesn't set off any alarms for me. There have been many good tandem wheels built with 36 spokes and low profile rims.


Cheers,

Cameron

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Re: Reasons for wheel failures

Postby Trevtassie » Wed Aug 12, 2015 9:27 am

I had a lot of trouble with thick spokes and Alex rims. I used Aex Adventurers, which are probably close to the DM20 and Sapim Strong spokes on 36H hubs. Basically I worked out in the end that due to their thickness the spokes couldn't stretch enough (with rational spoke tensions) to keep the nipples under tension when unloaded. The solution was to use wick in Loctitie. I just toured 1600km in Hokkaido with 90kg me plus 40-50kg of bike and luggage. Hokkaido can be pretty rough on wheels, it gets 15m of snow in winter and +30C temps in summer and the less used (maintained) roads and footpaths cop a flogging from snow plows, frost heave and temperature extremes (plus the curbs are about 8" high). The wheels came back as true as they started with even spoke tensions.

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Re: Reasons for wheel failures

Postby Six13 » Sun Nov 29, 2015 2:46 pm

I bought some Fulcrum 7s off Gumtree for $70. The front has done 5,804.44km (according to the mighty Strava) and is totes true fine and dandy. Me plus bike plus stuff will be 100kg or so.
Image

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Re: Reasons for wheel failures

Postby sampsont8 » Sun Feb 21, 2016 11:59 pm

Hi I have some Mavic ES helium wheels which has a cracked rim around the spoke!!! Mavic only has tub replacement rims at the moment which I don't really want. Does anyone have an idea of a rim that I maybe able use as a replacement to the mavic ones or if that's even possible!
Cheers Todd

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Re: Reasons for wheel failures

Postby Lukeyboy » Sun Apr 24, 2016 12:03 pm

Any rim would be compatible providing that the rim depths and dimensions are the same otherwise its new spokes required.

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Re: Mavic Aksium

Postby Kimmo » Sat Nov 02, 2019 10:48 pm

ironhanglider wrote:
Sat Sep 01, 2012 8:30 pm
I'll chime in with some wheel building theory. Note that I am not any form of engineer or describe myself as an expert, I have merely read some of the books and read some forums like rec.bicycles.tech for a long time where people like Jobst Brandt and Sheldon Brown would contribute. I have also built many wheels for myself, family, friends and customers (when I worked in various bike shops) and have found the following points to hold true.

- Spokes lose tension temporarily when they reach the bottom of the wheel when they are being ridden.
- The fewer spokes there are the more tension each spoke will lose at the bottom
- The more flexible the rim is the more tension each spoke lose at the bottom, lighter and shallower rims tend to be more flexible
- Higher tyre pressure will reduce the tension in all the spokes
- Higher loads (weight) will reduce the tension in the spokes at the bottom
- Pedalling action will reduce the tension in the 'pushing' spokes
- Impacts will reduce the tension (presumably at the bottom).
- Spokes that lose all tension cause problems such as the nipples unwinding and the spoke fatiguing and failing particularly at the elbow (and less commonly at the start of the threads)
- Nipples unwinding can be solved by thread lockers such as loctite, linseed oil etc, or by increasing the tension in the spokes
- Fatigue failures can be dramatically reduced by stress relieving the spokes but for some reason many wheel builders don't do this and few factory build wheels are
- Highly tensioned spokes tend to result in wheels that are less prone to require re-truing.
- Wheels built with highly tensioned spokes are more likely to have fatigue failures in the form of cracking around the spoke holes.
- Wheels built with highly tensioned spokes are more prone to 'potato chip' failures
- Spokes are almost never broken from too much tension.

As you can see some of these factors will combine together this explains why the most common spoke breakage is at the elbow of a pushing spoke. But the weight the wheel carries is almost certainly the largest factor. This explains why the most powerful sprinters still use low spoke count wheels, whereas 40 and 48 spoke wheels are common on touring bikes and tandems. Historically many bikes (British at least) were built with 40 spoke rear and 32 spoke front wheels to reflect the different loads. Somewhere along the way someone figured out that it was cheaper to use the same drillings for the rims and suddenly 36 spoke F&R wheels were standard even for high performance wheels. Then someone got the idea that fewer spokes were lighter and that most high performance wheels were used by people who could get away with 32 spokes. This was in the days of low profile sub 300g rims. Then came the deeper section rims, I suspect more for strength than anything else but they were also marketed as being more aero. This allowed builders to use fewer spokes again but come with a weight penalty. Sheldon said that having the same spoking F&R means that you either have a front wheel that is unnecessarily strong (and therefore heavy) or you have a rear that is not strong enough.

Velocity Deep Vs are renowned as being strong rims, but they weigh in a 520g or so. If I were to build a set of wheels with these I could probably get away with 24R, 20F spoking even though I weigh 110kg at the moment :oops: Although I'm not particularly hard on wheels. In fact my race wheels have carbon rims that are lighter but deeper than this.
toolonglegs wrote:My Aksium lasted about 1000kms before it totally destroyed itself... Cracks on every spoke hole... Not the greatest wheel for a big guy. But this was 2006 so they may have improved.
I like Mavic wheels ( live 10 km's from the factory )... But I never keep them after the 2 year warranty is up!.
If I were to build a set of wheels for TLL for example they would end up being heavier and have more spokes than he would choose to use so it is no surprise that he goes through wheels at a steady rate. The next best solution would be to tension them up higher and hope that he breaks them through some non-warranty mis-adventure before the rims cracked through fatigue.
bardygrub wrote:Before the service i had a slight buckle in the front wheel, which i reported and they trued the wheel. After about three rides i noticed the wheel was buckled again, checked the tension of each spoke and found one compleately loose.
Wheels that have low spoke counts are more susceptible to having the nipples unscrew due to the de-tensioning at the bottom of the wheel. Once this process starts a spoke loses even more tension which is what bardygrub found. The solution is either a threadlocker to stop it unscrewing, or more tension overall. (or wheels that have either more spokes or heavier rims)
rkelsen wrote:Your tyre pressure is too high.
Increased tyre pressure does contribute to the unscrewing of the nipples by reducing the tension in the wheel overall, and possibly also by not letting the tyre cushion impacts as well. Some of rkelsen's other wheel woes sound also sound like either a lack of tension and a failure to stress relieve the spokes, the tyre pressure contributed to the lower tension. The commuter wheel also sounds as if it was afflicted by a bad batch of spokes. Shogun Metro SE's were famous for this in the early 90's and Sapim had trouble with a batch recently (2007?) too.

Part of wheelbuilding is science and you can plug in the numbers and say that for a given weight and rim you need x number of spokes in each wheel at x tension, part if it is art because some riders are just harder on wheels than others of similar weight/height/power. It is easy to overbuild wheels to make them reliable, but to put 48 spoke Deep Vs under a 45kg climber will not give them good performance. This is where the good builders (like TWE) really add value to extract maximum performance at adequate strength/reliability.

Thanks for reading such a long diatribe.

Cheers,

Cameron
This is a great post, and I agree with almost all of it. BTW, the first paragraph also applies to me.

But here's the bit I disagree with:
Wheels that have low spoke counts are more susceptible to having the nipples unscrew due to the de-tensioning at the bottom of the wheel.
It's quite probably true that low spoke count wheels experience a greater change in each spoke's tension as they rotate past the ground, but I'd say this is more than made up for by the fact that the spokes have to be at higher tension. There are zillions of Shimano's various 16/20 hole wheelsets out there, and they've proved extremely reliable.

Yes, they require the rim to be stronger, but these days we have carbon, and rims with local reinforcement at the spoke holes. Shimano's laminated carbon/ally rims weigh 360g. My 50mm deep Caden tubular rims weigh 310g, and are 16/21.

The bloke banging on about stuff being less reliable these days was talking utter bunk. As if hub drag matters a damn... It's a vanishingly small contribution to overall drag, and we enjoy more reliable hubs thanks to better sealing. Materials and design are both vastly improved from forty years ago, no question. All this talk of breaking elbows, and you don't even have to have spoke elbows anymore.

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Thoglette
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Re: Mavic Aksium

Postby Thoglette » Sun Nov 03, 2019 8:25 pm

Kimmo wrote:
Sat Nov 02, 2019 10:48 pm
The bloke banging on about stuff being less reliable these days was talking utter bunk.
It's sort of true because only the good stuff has survived: the BSO's fencing wire wheels on rolled steel rims have long gone the way of all flesh.

I'm old enough to remember the crap as well as the good bits. The problem at the moment is that the vast majority of wheels are machine made and not hand finished (by someone who does it every day). That $40 to $60 extra that you're paying per wheel is buying you a significantly better wheel.

Yes, I can, have, and probably will build my own wheels (again, someday) but the difference in the amount of through-life re-truing between one of my wheels and one made by a "real" wheel builder is, unfortunately, very noticeable.

BSO grade machine made wheels remain wildly variable (between OK and utter crap).
Stop handing them the stick! - Dave Moulton
"People are worthy of respect, ideas are not." Peter Ellerton, UQ

Kimmo
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Re: Reasons for wheel failures

Postby Kimmo » Sun Nov 03, 2019 10:40 pm

Wheel building machines are better these days; they can set them to do higher tension now that they can account for spoke windup. If you compare cheap wheels of today from those of years gone by, you'll find higher tension. Rims tend to be a bit beefier too; box sections are pretty rare now.

And if you're talking say, RS11 for a cheap wheelset, anything 16/20 from Shimano is built pretty nicely. There's less difference between a decent machine built wheel and a hand built wheel these days.

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baabaa
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Re: Reasons for wheel failures

Postby baabaa » Tue Nov 05, 2019 6:34 pm

This, all online opinions on the highest and lowest quality (and priced) bike stuff should adopt this sort of manner

Mr Purple
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Re: Reasons for wheel failures

Postby Mr Purple » Sat Feb 06, 2021 12:16 pm

After buying a pair of the cheapest rims Kotavelo makes ($150 for 1700g which is an absolute bargain and I can't complain too much at that price) I wouldn't do it again!

Nice, light, well trued. But the cheapo hubs (and you'd expect that for the price) started randomly grabbing about 1000km in. Very intermittent problem - turning the bike into a fixie for half a pedal stroke occasionally and given I'm a fairly new rider I couldn't recognise it. Until it threw the chain into the rear wheel, fortunately while climbing. One rear wheel gone, derailleur and hanger destroyed, and an almost brand new Pirelli tyre and tube busted. Fortunately I stayed upright. Hate to think what would have happened if I was going faster than 30km/hr uphill.

Lesson learned. It scares me that a lot of $600-700 wheelsets appear to use the same hubs. My new wheels are built with DT Swisse 350s. And a $110 Tiagra rear wheel while I wait for the new bike has proved absolutely bulletproof.

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