To what extent are rear wheels consumable parts?

[gaijintendo]

Hello team,

I seem to have a lot of problems with my rear wheels on my commuter. First up, I should say I am rocking 15 stone, but not a lot of fat... not that the bike cares.

I ride a Kaffenback 2, and I love the thing, but the Shimano Rx05 it came with were losing a spoke a month before I made it a dedicated turbo trainer wheel (no probs since, but that's because "turbo" and "unused" are almost synonyms).

I replaced it with the budget LBS recommended rear wheel (something like a Mach 1? It has a Shimano hub and I didn't keep the stickers on long) - 32 spokes and it has been fine basically. When I dusted the bike off in the first splash of sun this year I noticed some severe structural issues.

Is 13 months acceptable for a wheel? I use it every weekday for about 16k a day, and a couple of times a year for a century. My Schwalbe Marathon Plus on this thing will have outlived two wheelsets, and still looks fine...

I guess the only other questions are, is there any point showing this to the LBS - and is there a well established wheel for fatties?

 

[Drago]

I'm a big bloatie fatty and I've never had any undue wheel problems. Unless you're in Giant Haystacks territory any typical wheel, if well assembled, should be fine.

 

[CanucksTraveller]

I think I'd be pretty disappointed with a year from a wheel, to me they're certainly not consumables. I'm on 6 years on my hybrid (stock Trek / Bontrager wheels) and I'm not expecting to change them any time soon, although I currently do less miles on it than you do.... shouldn't matter a great deal, it's not like you're hammering them.

I do think you can get wheels that are known for being better for heavier riders, but at 15 stone I don't think you're anywhere near the truly heavy camp. There are many people who are 15 stone and more that ride skinny road bike wheels.

 

[gaijintendo]

Thanks for the responses. @CanucksTraveller I try not to hammer them - it is mostly roads, and I know where the bad bits are...

Yea, my previous bike was a 26" Norco Citadel with, I think Alex rims, and it made it a decade... I guess I will just save up and get something from a known brand.

Cheers @Drago, I might take a look at some Mavic wheel deals kicking around, unless someone knows of a better thing to look for. They seem to be a good brand, and occasionally look to be discounted.

 

[Tim Hall]

I'm only a bit lighter than you (although I measure in kg, so it's hard to be sure). Anyway, my favourite bike has got 32 spoke Ambrosio Evolution 700c rims with Saipim something or other double butted spokes. I had a hand in building them, but my friend Dave, who has done this many times, did the clever stuff, getting them properly true and nicely tensioned. They've been going two years (possibly three) and are used for commuting and leisure riding. So, no, not really consumable in the way you show. I think that's down to poor construction. Rims will wear out eventually, due to the brake wearing the material away, but that's another story.

 

[Yellow Saddle]

Hello team,

I seem to have a lot of problems with my rear wheels on my commuter. First up, I should say I am rocking 15 stone, but not a lot of fat... not that the bike cares.

I ride a Kaffenback 2, and I love the thing, but the Shimano Rx05 it came with were losing a spoke a month before I made it a dedicated turbo trainer wheel (no probs since, but that's because "turbo" and "unused" are almost synonyms).

I replaced it with the budget LBS recommended rear wheel (something like a Mach 1? It has a Shimano hub and I didn't keep the stickers on long) - 32 spokes and it has been fine basically. When I dusted the bike off in the first splash of sun this year I noticed some severe structural issues.

Is 13 months acceptable for a wheel? I use it every weekday for about 16k a day, and a couple of times a year for a century. My Schwalbe Marathon Plus on this thing will have outlived two wheelsets, and still looks fine...

I guess the only other questions are, is there any point showing this to the LBS - and is there a well established wheel for fatties?

Those wheels didn't have enough spokes for your weight. You need at least 36 spokes per wheel.

 

[Hugh Manatee]

@Spoked Wheels will have something worthy to say. Could the tension have been cranked up on the spokes too much? I don't weigh quite as much (closer than I'd like) and I have old (thin) Ultegra 9 speed hubs laced to Open 4CD rims in 36 spoke flavour. Never had any problem and they must be quite old to say the least.

 

[Tim Hall]

Those wheels didn't have enough spokes for your weight. You need at least 36 spokes per wheel.

That's what I thought, until I did a conversion of my 91kg to stone. The OP is only about 4kg more than me. I'm quite willing to accept that's the straw that broke the camel's underspoked wheel, but it's fairly close to what I weigh. Mind you we don't know how much stuff he's carrying, or what the bike weighs.

 

[gaijintendo]

That's what I thought, until I did a conversion of my 91kg to stone. The OP is only about 4kg more than me. I'm quite willing to accept that's the straw that broke the camel's underspoked wheel, but it's fairly close to what I weigh. Mind you we don't know how much stuff he's carrying, or what the bike weighs.

Yeah, the bike is tooled up with a rack, guards, every consideration for comfort, none for weight. But if it weighed 15kg, then that adds a couple of straws to the camel. I suspect a lot of this comes down to being a low end wheelset, and a higher end crisp addiction.

My criteria so far: 36 spokes.

 

[Drago]

Not wishing to turn this into a lard pishing contest, but I'm 116 wheels have never been an issue for me. I suspect the OPs wheel was inherently faulty some way from the start.

 

[gaijintendo]

Not wishing to turn this into a lard pishing contest, but I'm 116 wheels have never been an issue for me. I suspect the OPs wheel was inherently faulty some way from the start.

You made me weigh in earlier... 15stone 10lb or just shy of 100kg... so that's even more straws on Tim's camel from earlier.

 

[Deleted member 35268]

I seem to be able to trash a set of wheels every two years one way or another. That's about 9000 miles of potholes and abuse. The wheelsets that have terminated have either died from freehub wear, rim damage from potholes or gradual spoke failure which becomes repetitive. I've never had a spoke pull through the rim though. I don't buy expensive wheels, I can't afford them so they all tend to be £100 sets.

 

[gaijintendo]

I seem to be able to trash a set of wheels every two years one way or another. That's about 9000 miles of potholes and abuse. The wheelsets that have terminated have either died from freehub wear, rim damage from potholes or gradual spoke failure which becomes repetitive. I've never had a spoke pull through the rim though. I don't buy expensive wheels, I can't afford them so they all tend to be £100 sets.

Sounds familiar... Unless someone can recommend me a tank, I'm probably destined to repeat that cycle.
I took the wheel to the shop to let him see, because it seemed a bit weird to me. It had lost a spoke and had it replaced quickly, so it would have been trued aside from my last service.
They were going to show it to the distributor. He was surprised as it isn't otherwise beaten up, and it was double walled, so will see if anything comes of that but i certainly won't be demanding anything from them.

 

[Yellow Saddle]

Sounds familiar... Unless someone can recommend me a tank, I'm probably destined to repeat that cycle.
I took the wheel to the shop to let him see, because it seemed a bit weird to me. It had lost a spoke and had it replaced quickly, so it would have been trued aside from my last service.
They were going to show it to the distributor. He was surprised as it isn't otherwise beaten up, and it was double walled, so will see if anything comes of that but i certainly won't be demanding anything from them.

You can do a few things to improve the frequency of wheels cracking up like that.

1) You can find plain silver rims rather than black anodised ones.
2) You can find double-eyelet rims rather than single eyelet ones.
3) You can increase the spoke count.

It isn't all that obvious but anodising on aluminium weakens the structure. Anodising is a ceramic coating that sits half on top of the aluminium and half inside it. The thicker (darker colour) the anodising, the deeper penetrates into the aluminium. It is a very, very hard substance but also brittle. It breaks like glass when flexed. If you look carefully at an anodised rim around the eyelet, or just bend a piece of anodised aluminium, you'll see tiny little cracks. These propagate into the substrate and initiate larger cracks, as in your photo. The concept works exactly like a heavily scabbed-over knee that's bent when the scab is dry. I'm sure you get thepicture.
The solution is to look for silver rims since those are anodised very superficially.

Most rims nowadays are double-walled, but the real durable ones have socketed eyelets that pull on the inside and outside wall. I bet yours are have only single eyelets.

Here's an example of such a rim. I've cut it through just before the socket so you can see it.

By increasing the spoke count, you increase the number of spokes that share each tension cycle on the spoke. Spokes and rims are under constant tension (and thus no faitigue) up to the moment when that spoke is right above the wheel's contact patch. A short length of rim in that zone is then compressed, with the effect that the spokes and rim lose tension. As soon as the wheel rolls over that spoke, the tension returns. With each revolution it thus detensions and then re-tensions. It is these repeated cycles that cause metal fatigue. If you increase the spoke count, more spokes share the load affected zone and each spoke then does less work and each little teat that's pulled in the rim, relaxes less and the aluminium fatigues less.

I doubt you'll find your optimal wheel just off the shelf. You may need to find someone to build you such a wheel.

 

[mustang1]

Me plus bag are about 100kg. Dunno how many stones that is. I have magic aksium and 25mm tires and commute about 25 miles daily which also includes light off-road stuff and plenty of bunny hopping.

The wheels are serviced annually and I've had zero problem in the last 5 years. (Before that i had another bike).