Hey all,

Having just experienced an almost collapsed wheel, I’m looking for some opinions on what folk think makes the strongest back wheel.

My current wheel is a stans flow ex on dt swiss hubs with 3 cross, interlaced asymmetric spokes. Question for me … will symmetric lacing make the wheel stronger or will there be bee haw difference?

Could look into tandem hubs and wheels? They’re really really strong.

Asymetric as in the pushing/pulling are on the inside/outside on the drive and non drive side? There’s various logics to it (IMO the pushing spokes should be on the outside, so that braking forces push the spokes away from the disk and if the chain derails it doesn’t get jammed between cassette and spokes) but neither should have any meaningful effect on the overall strength.

What you had should have been pretty tough, the most important factor is how well it was built (and how much abuse it’s since had), if the tensions not even it won’t last long.

Get something that uses 36 spokes, DH rims or both?

mavic 729 rim, sapim strong spokes throughout, and hope pro2 36 spoke hubs.

built by Spa cycles Harrogate

these stayed true on a 40lb e bike with a 23 stone rider.

I’ve had Mavic 729s before, it is a massively strong rim. But then again, how are you managing to break them in the first place, OP?

Stronger rims.
WC guys can do a Flow per run at Fort Bill (more due to denting than destroying them).If you are ‘almost collapsing’ during normal riding then you are possibly doing it wrong 😉 and stronger wheels will likely lead to something else failing (catastrophically).

Original D321’s on Pro 2, with fully equalised spoke tension. Coincidentally, that’s what I built 😀 not moved more than 1mm in 5 years of abuse.

What you had is a pretty solid build-IF they were built well in the first place.
There are at least two sets I’ve built of Flow EX’s doing World Cup DH races, as well as BDS & I’ve had one back once this year for a true up, which was due to a crash & snapped a spoke.

I’ve personally never had a hub or a rim fail, whenever I’ve destroyed a wheel it’s been the spokes giving in which taco the rim.

As long as you’re not asking too much from it – iE a super light XC build on a DH bike or something it comes down to the build and the builder – no need for 729s unless you’re riding DH on a big arse DH bike, they are indeed insanely strong, but they weigh a tonne and will numb most bikes – I ran a set on my Enduro in 2006 after smashing a poorly built wheel, it was rubbish.

A decent rim with decent spoked built by someone who knows what they’re doing won’t fail – just give the spokes a squeeze every few months to make sure everything is okay.

Stans are made of soft cheese.

Mavic EN 821 or EX 729 on Hope Pro 2 EVO, DT Swiss DB spokes with brass nipples.

Yes. Double butted [DB] spokes are stronger AND lighter.

Good even tension is all you should really need. I’m not a massive fan of Stans as they’ve no eyelets (it’s a personal thing TBH, it probably doesn’t make that much difference for most folk), like DT and Sapim spokes. Hub doesn’t really matter.

If you’re a big lad a 36 on the back is a good idea.

hope trials on mtx33.
36h, dishless.

you can run 1/2×6/7.dt comps.

even spoke tension.

gofasterstripes – Member
Yes. Double butted [DB] spokes are stronger AND lighter.

Wrong! Better fatigue life, not stronger.

these are very strong.

http://www.sapim.be/spokes/butted/strong

What actually happened? Do you need a stronger rim or maybe just a better built one, or better servicing? Or, perhaps, do you need to stop doing damn fool things that destroy rims, like me?

Flow Ex is a great rim but not all that strong- no wonder when you consider the weight. If you want something similiar but stronger consider the WTB Frequency i25, it’s heavier but a little wider and ime a lot tougher. (I replaced a cracked flow and a flattened flow ex with one). I had no complaints about the strength of the flow, mind, I just used it for stuff that it wasn’t happy with.

More spokes. They weigh bugger all.

For my bikes it’s 36 hole wheels and 3 cross. There’s plenty strong enough wheels with less, but you have more of a margin with 36 holes. Trouble is there’s not a lot of rim choice these days compared to 32 hole.

More spokes. They weigh bugger all.

True, and relatively speaking, true. Although looked at in isolation, just adding more spokes often won’t yeild the strength improvements required. That is to say, take the same rim and hub, but build a 32H and a 36H version of each (using the same spokes), and the 36H version will be stiffer and/or stronger.

It’s not likely to be enough of an improvement though, for someone regularly casing their current wheels… To get enough of a difference strength wise for it to make a case for itself, often you need to start looking at significantly stronger rims…

Got to agree with ton et al regarding Mavic EX729’s… If you need strong 26″ rims, then these are as good as ubeatable! They’re not light, but they’ll take years and years of serious abuse.

They make a weaker wheel – one which is more likely to collapse.

A good wheel builder.

Mag wheels!!! 😆

What actually happened was that pretty much every spoke lost tension on a very long dragging brake downhill. I’ve never had this problem with this wheelbuilder on similar wheels (only difference is the suspect wheel is 27.5 and others have been 26). When I took the wheel to a bike shop near the downhill, they said the wheel should have been symmetrically laced as it is way stronger for a rear wheel. I can’t see anything online to suggest that and I’m looking for what people think of it. I didn’t mention this my original post as I didn’t want to prejudice the question.

It was a weird thing to happen, that’s for sure, especially as I rarely buckle wheels and Stan’s have been fantastic rims for me in the past (still running true after 6 years on one bike).

Lost tension means the build was not up to it, noting to do with strength.

Symmetrical build = hogwash.

When I was a lad, rims weren’t as good as they are now. We preferred 40 hole rear wheels for strength.

aracer – Member
“gofasterstripes » Yes. Double butted [DB] spokes are stronger AND lighter.”
They make a weaker wheel – one which is more likely to collapse.

Any evidence of that? It runs contrary to everything I’ve learned about wheels, but I don’t do downhill, so I’m interested.

It seems sort of self evident that if you use a 1.8 section in the middle of the spoke instead of 2, then the middle of the spoke will not be as strong, but my understanding is that is not how it works.

The benefit of double butted is you are less likely to get breakages at the nipple or elbow and I’ve never heard of a double butted spoke breaking in the centre. Even a 1.8 section is incredibly strong.

Perhaps a proper engineer like trail-rat could chime in.

Fat Boy Fat.

your wheel losing tension like that means wheel wasn’t built well enough in the first place. Probably wasn’t laterally true. This I’d say about a wheel that would have had “very” loose spokes though, like finger wobbly loose, get it rebuilt (if it’s still viable) and after a few rides check the spoke tension again. Look for loose spokes (not whether they all need one more 1/4 qtr turn).

edit was this a 29?

+1 for wheel tension. Even the strongest rim and spoke combination is going to flop quickly if the wheel isn’t well built, I know because I’ve botched a wheel build and have had bendy wheels as a result.

I’ve had factory built wheels that have lost tension and gone baggy over time, but a wheelbuilder who knows his stuff will be able to build you something strong and light (relatively speaking).

I had a flow ex in the back of my dh bike that went floppy following an issue with the axle coming lose. The wheel didn’t collapse though and stupidly I didn’t work out the issue until I got home. About 4 runs later.
I can’t believe it is anything to do with the rim

@aracer – Sheldon doesn’t think so. Drawing steel can strengthen it, which is why frames are butted, and steel ones are often drawn/butted. Also they can be more elastic, sharing the load better.

Any evidence of that? It runs contrary to everything I’ve learned about wheels, but I don’t do downhill, so I’m interested.

It’s a bit more complicated than just the strength of 1 spoke though.

Think about an impact to the bottom of the wheel at about 45deg to vertical (a really sideways landing, or clipping a rock mid corner for example). The spokes in the top half of the wheel at that instant take the vertical loads, so the strength of the wheel is purely down to the unsupported bottom half of the rim and the spokes will have little impact on strength. The sideways component of the force is taken (initially) by 1 spoke in the 6 o’clock position, which if it is too stiff puts all that force on one eyelet in the rim. A thinner spoke stretches, letting the rim deform, transferring more load to the spokes around it and reducing the force on each individual spoke.

That’s how I think about it anyway, and that’s why I’m happily riding around with 1.5mm spokes on stans alpha rims on my road bike despite me being a certified member of the tubby funster demographic. The thinner spokes prevent too much stress being concentrated in one part of the rim.

The spokes are individually weaker, but you won’t tear them out of the rim/hub as easily so the wheel is stronger overall.

I’ve always used DB spokes, but that’s only because the bloke that taught me how to build wheels, said “Always use double butted spokes, they’re better than plain gauge” 😆

There’ nothing in that wheel that would cause me to say “oooh, wouldn’t use that” I’ve only built normal 3 cross wheels, but I have used thicker spokes on the right hand side of rear wheels (drive side) before, and thinner spokers for the left. You can get more tension with thinner spokes, and then they’re less likely to go slack. (wheel builder nerd territory). I ask about 29 because I’ve heard that 29 wheels built with too much tension (over 125kg) will unwind easier… Dunno if it’s true though

It seems sort of self evident that if you use a 1.8 section in the middle of the spoke instead of 2, then the middle of the spoke will not be as strong, but my understanding is that is not how it works.

In terms of ultimate strength that is how it works.

4x lacing.

I think it’s just “rear wheel” TBH, they’re inherently a bit dicey if you ask me. If anything’s going to go wrong, it’ll be the rear. 😆

cynic-al – Member
‘It seems sort of self evident that if you use a 1.8 section in the middle of the spoke instead of 2, then the middle of the spoke will not be as strong, but my understanding is that is not how it works.’
In terms of ultimate strength that is how it works.

Yes, that is true, but the strength of even the 1.8 section is more than adequate. I have never heard of a butted spoke breaking in the middle unless it has been damaged by the chain or derailleur – which is why in the days of really crap derailleurs we had those plastic spoke protectors.

In ’07 when i first started mtbering (after a long history of bmxering) i was going through back wheels a fair bit. Ended up with a Halo SAS rear and it’s still going strong today. 48 spokes ftw.

I heard that Rennie and Kovarik used to have the spoke crossings og their rear wheels spot welded for strength