noisebeam

I have a Mavic MA3 rim (prebuilt with Surly hub) on my fixed gear with ~5k of trouble free miles in ~1yr.

However in the last day or so one spoke ripped up the rim and caused a good 1.5" of tear in the rim on either side if the spoke.

Roads here are generally smooth with the occassional bump, but no major pothole, I weigh 185.

Is this a wheel defect? A build problem (bad tensioning)?

Should I have to pay in full for a new rim and build?

Al

simplify

Sorry to say, this has been something of a common problem on the MA-3's. Way more of them did this than could be explained by conditions or a bad build. I would definitely at least try to get a replacement through your dealer or through Mavic, especially if it's less than a year old.

moxfyre

Yoikes! I have MA3's on my touring bike... hope they don't suffer a similar fate I agree with lawkd that since these are only 1 year old, they should either be under warranty or if you complain enough to Mavic they'll want to make it right with you.

TallRider

Yup. I've stayed away from MA3's when I build wheels because of this reputation. If you want a similar-design, relatively cheap rim, the Sun M13II is pretty good. But there are lots of good rims out there. Mavic's new "Open Sport" is the replacement for the MA3 and it's pretty similar, but I don't know if they've corrected the eyelet-cracking issue...

noisebeam

I just got back from the shop and they are going to rebuild the wheel with the next step up from 'open sport' (forgot what they are called, but cost $20 more for the rim). They thought that 5k miles was good for that wheel on a fixed gear. Anyway, its not going to be covered by Mavic as the warrantee is 1yr and the wheel is 14mo. old. So its all in total gonna cost ~$110. ($60 rim, $30 build $20 other bits and tax)

This was not an eyelet cracking, but the rim itself away from the eyelet by >3/16", like a 2" strip of the inside of the rim lifted up, with 2" cracks on each side of the spoke about where the inside of the rim transitions from flat to the vertical edge.

Al

simplify

I cannot agree that 5K miles is reasonable, even on a fixed gear. They should have cut you a better deal than that, IMO.

noisebeam

It is not the shop that cuts the deal, it is Mavic. The shop still will try and warantee the wheel with Mavic, but told me it was very unlikely as it was past the 1yr. mark.

Al

moxfyre

I agree. 5K is a totally unacceptable lifetime for a rim. Why should the rim not last as long on a fixed gear, exactly??? Just because there's more force transmitted from the hub to the rim in deceleration???

It seems like some shops will throw any excuse at you for why a part has failed. "Oh, well at your weight a square-taper crank just won't last long." "Oh, well with that chain it's not surprising the derailer isn't working right." "Oh, well your riding position puts a lot of stress on that seatpost." Etc. etc...

noisebeam

They told me that a fixed get a lot more torque (which doesn't make sense to me, a multi gear bike in a low gear going up a hill or starting from a stop at the same speed should have the same forces at the rim)

Anyway, the 5k miles is irrellevant, I could have ridden 3mi or 30000 miles, and it still wouldn't matter as the warantee is time based not mileage.

But I do agree its BS, I also wonder that since this was a prebuilt wheel (isn't the MA3/Surly a QBP wheel) maybe QBP can be contacted.

Al

moxfyre

A fixed gear in forward motion has the exact same torque on the rim as a geared bike used in the same gear. So if I am in a 39/15 gear with 170 mm cranks and 610 mm rim ERD, the torque transmitted to the rim through the spokes is 4.67 times the torque on the cranks from the pedals (= 305/170 * 39/15).

When you slow down a fixed gear by resisting the motion of the pedals, the torque will be worked out the same, but is in the opposite direction. A semi-tangent wheel can withstand basically the same torque in either direction, because there are as many leading as trailing spokes.

The only situation I can think of where a fixie might have excessive torque on the rims, and thus excessive force on the spokes, is if you like to slow down by skidding and skipping. In this case, you're applying reverse torque on the wheel with your feet, while the contact with the ground applies forward torque (though not much of it if you're sliding). If you rided a braked fixie, you probably don't use this stopping technique since it's very hard on the tires, sprockets, and chain, as well as being hard to do and somewhat dangerous.

I think that it's BS to claim 5k is an acceptable lifetime for ANY kind of rim used on the road. Don't know enough about MTB to comment there.

noisebeam

You echoed exactly what I was saying about torque on the rim. As to slowing, I do use a front brake and don't skid/skip, primarily to save wear and tear on tires. (although when I first build up the bike I did a fair amount just to learn) Also all mileage is on good roads, mostly in higher speed pacelines during weekend rides. Perhaps I'l be a bit firmer about getting some form of price reduction or having them push harder for Mavic/QBP to help out.
Al

sivat

Are they rebuilding the wheel with the same spokes? Thats usually a bad idea

noisebeam

I have no idea, but I assume so. If a very bad idea, I could give them a ring and tell them not to if they haven't started (said it wouldn't be ready until tomorrow late)
Al

Rowan

Read this to get a take on Mavic's regard for its end-users. It seems age has not wearied Jobst's assertions and arguments.

TallRider

A fixed-gear doesn't get more torque. Actually, a fixed rear wheel should be more durable because it's not dished, so spoke tension (and to some degree torque, depending on the stiffness and diameter of the hub shell) are more evenly shared between drive- and non-driv-side spokes.

5,000 miles isn't good, especially for a fixed-gear rear wheel, but it's not horrible either, especially for the MA3. The shop may have built a good wheel, the MA3 just fails like this sometimes. The bike shop shouldn't really be expected to pay for it unless they did a bad build.

My guess is they're building up your new rear wheel with the Open Pro. Good solid rim. Make sure they build up with double-butted spokes - makes for a more durable wheel (butted spokes flex more in the middle, but are less of a danger to either go out of tension *or* break as a result of this). The rim is less likely to fail with double-butted spokes, also.
New spokes aren't always necessary; if the previous rim failed b/c excessive spoke tension (usually the case when rim cracks), then spokes may well be okay. Spokes are more likely to fail when they're too loose, because then they flex more under repetitive stress. I've rebuilt wheels using old spokes before and new ones have been fine. But if you're going to reuse spokes, you need the replacement rim to have hte same effective rim diameter as hte previous rim, and the Open Pro has a significantly smaller ERD (requiring shorter spokes) than the MA3.

noisebeam

Thanks - yep Open Pro it is. So it sounds like the shop must use new spokes due to length difference. So a phone call is only needed if I am to request double butted spokes (vs. them probably using the cheapest ones they have around)
I don't have a gripe at all with the shop, I don't expect them to pay (as I said before I am not even sure if the shop built the wheel, I think, but do not know that this Surly/MA3 is a ready made wheel from QBP), my gripe is just with Mavic for selling a rim that has (possible) design defect.

The spokes seemed quite tight. I did say the rim was problem free, but in its first 100 mi or so, one spoke did come loose and snugging it didn't help. Took it to the shop and they did something (locktite i think) to keep it tight. But it remained very true thoughout its life. Never saw a brake pad either.
Al

TallRider

It's kind of a waste to have pretty machined-rim braking surface on a rim that's never going to see a brake pad. (On the other hand, machining doesn't really matter after you've ridden in the rain a few times and gotten some scouring grit in your brake pads.) The plus-side is that the machined brake track does look pretty, and stays looking pretty if you don't actually touch it with brake pads. But you could just get the shop to order the Sun M13II or CR18 (the latter bettre if you're running wider tires - 28c or wider); these rims are single-eyeletted design, same as MA3 whereas the Open pro has double eyelets. But the Sun rims have a good repuation for durability and are used by lots of bicycle messengers. They run about $30.

noisebeam

Thanks for the tip. Two reasons to go with the Open Pro: The shop has it in stock (also a CXP33) and I need this fixed quick as it is my only transport to work (I have two bikes but the other is being worked on too) the other is that I will eventually put a 700c wheel on the front (right now using 27") and that wheel will see a brake and it will be nice if it matches the rear.
Al

TallRider

The quick turnaround is a good reason. My fixed-gear bike has 27" wheels, an M13II on the rear. M13II handles brake pads fine, btw - I've built a couple of 700c wheels using this rim and it's nice enough.

If the shop hasn't built your wheel yet, I'd recommend spending the extra $10 for the CXP33 which has a great rep for durability and isn't that much heavier than than the Open Pro. (That said, my good road bike has an OP rear rim on a standard dished rear wheel, and I weigh 180 pounds and trust it just fine.)

halfspeed

Time for new rims. You DON'T want to them to crack on tour. They aren't adequate touring rims and their well-documented problems are real. I just replaced one with 2000 miles on it.

moxfyre

Yeah, I haven't done an actual tour on them yet I'd like to do a tour of the Eastern Shore of Maryland. I lack sufficient money and time to do a tour in any kind of remote place.

My MA3s currently have 3500 miles + whatever the previous owner put on them (probably not much). The rims seem totally fine, but don't get me started on the craptastic spoke tensioning on the rear wheel. Had about 5-8 broken spokes before I retensioned everything.

noisebeam

I picked up the new wheel yesterday evening. Open Pro with double butted spokes. Rode it into work 9mi this morning. Mechanic who built the wheel said to bring it in after a bit to recheck tensions, which was nice to hear as it shows he cares.
Al

TallRider

MA3's can last just fine, assuming you've got them in good tension etc. I don't know if it's a design issue (all MA3's subject to premature failure) or a quality control issue (some MA3's subject to premature failure). When they fail, it's almost always the rear wheel.

noisebeam, glad to hear the new wheel has worked out.

Rowan

It was stated by an highly regarded commercial wheelbuilder on another forum recently that NO well-built wheel needs spoke tension to be checked after being ridden a bit.

noisebeam

Maybe the builder wants to know if he built it well

Al