Sorry to flood the forum with another question (!!), but this last one is for a friend in need….!

A friend of mine is confused byy some advice he is getting about ‘drive side spokes’. He now needs to rebuild (respoke)his rear wheel yet again for the third time in about 18 months. It’s an MTB wheel that is not really getting much ‘abuse’ if any, made from a Hope Pro 2 rear hub (32 hole), a Mavic EN721 rim, and DT Swiss spokes that are Doublegauge. Each time, several spokes break on the drive side, where they rub the flange holes of the hub.

We are told this is a common problem, best reduced by using DG spokes. He is a powerful rider who just rides mud trails and streets daily really, not much else.

Does three rebuilds in 18 months sound right? Any suggestions of what is going wrong here?

Greenbikerider.

I’d say 3 rebuilds in 18months is excessive.
If he’s breaking spokes just riding round then he should be on the GB track team if he’s got that much power!

Realistically there’s either something wrong with the components,
or Badly built wheels(who is building them ,himself or a shop,do they know how to lace and tension them up correctly?)

Or lastly he doesnt ride light ie.Crashing over and through obstacles rather than trying to unweight the bike.

if he isn’t building with enough tension or repeatedly building onto an old, damaged rim, this could explain the breakages.

3 rebuilds in 10 years would surprise me given normal riding and no real crashes to speak of!

cheap spokes would also cause failures especially with a badly built wheel.

We are told this is a common problem, best reduced by using DG spokes

If the whjeelbuilder is telling you it’s a common problem then I’d go elsewhere.
It may be common to them but it ain’t common generally.

That’s a very stiff rim, so would still end up roundish even with really uneven spoke tension. If some spokes are over-tensioned then they could fail quickly. All the drive side ones need to ping the same note. It’s worth having a go with a tension meter too. The other thing is to relieve the bend in the spokes coming out from the flange while building, so that they draw a straight line to the rim. Otherwise they will flex and fatigue.
Worth trying some stronger DB spokes? DT Alpine or Sapim D-Light? These are thicker at the j bend.

Edit:

where they rub the flange holes of the hub

That’s most likely a problem with them not being bent to a straight line while building.

Is the issue not being caused by his chain popping over the big cog and gouging the spokes? Limit screw might need adjusting.

There’s no reason to use anything other than good quality doubt butted spokes for a start
It’s a fallacy that thicker spokes build stronger wheels. In fact they don’t have the stretch/recovery properties of a decent DB Spoke so you end up with a stiffer but more brittle and less resiliant wheel.
Any half decent LBS mechanic should know this. (I am one, I do know) it’s the very basics of wheelbuilding. Use good quality double butted spikes and brass nipples, properly built and tensioned, and there should be no problem. Go 36 spoke of you get the chance though. 4 more spikes will add a lot more strength than thicker ones.

Thanks everyone for your comments :o)

I agree that my friend has an odd problem to need a third rebuild so soon!!!

By the way, he has NO rear mech probs, it’s limited perfectly.

The wheelbuilder each time is Evans Cycles, I am told. Wheels are not my area of expertise, but for a start, I suspect they are NOT using the good quality spokes they claim to be! I too, find it very odd they are advising my mate that it is “a common problem” that “just happens sometimes”. I suspect they are crap at building wheels, full stop! (I don’t mind admitting myself, that I am no fan of Evans. But until now, assumed their “wheelbuilder expert” is rather crap!)

I just pinged his drive spokes remaining – they are all pitched very differently, suggesting tension chaos has erupted!

My friends rims were brand new 18 months ago, with the first custom wheel build Evans did. I personally don’t think they are part of the problem, just poor building. By the way, I am told that Evans have been ‘checking’ the wheel every 3 months. I’m not clear what spoke tweeking they have done (badly?), but my friend has sworn on oath never to approach them (or Half**ds) again (this is my personal 1st holy ommandment of cycling!), and seek quality workshops instead.

Thanks good people!

Greenbikerider.

Glad to help!

If there’s already broken spokes, then the tension will be all over the place, as the adjacent spokes will have to accommodate.

If you’re anywhere near Reading, I could rebuild them if you’d like.

Any half decent LBS mechanic should know this. (I am one, I do know)

Ooooh get her 😉

The last wheels that I built for myself were 29er wheels with 1.8mm spokes. I swapped out the brass nipples for alloy and just threadlocked everything in place….. They held up without any adjustment for over a year of riding in British Columbia and were fine when I sold the bike. You are certainly correct with the physics, but the quality of the build is more important as long as you are at least using branded stuff.

(For the record, I wouldn’t have built the above wheels using those spokes for choice, but I didn’t trust the factory build so re-laced them and used some alloy nipples as I have a million of them lying around).

where they rub the flange holes of the hub.

Too little tension!

Cause #1 Play between the hub and the spoke. When a bike is ridden, its wheels are placed under radial loads and the rim flattens out a little as it presses against the road surface. Each spoke is therefore placed under load and relieved once every rotation of the wheel. A wheel which has covered 1,250 miles has been subjected to a million load changes! … And so a wheel with 32 spokes has been subjected to 32 million load changes! The attachment point of the spoke to the hub suffers a great deal during these load changes. If the spokes head and elbow is seated perfectly in the hub flange, without any play at all, then nothing can go wrong. But if the attachment point has the tiniest amount of play, then you have a spoke failure waiting to happen. Every time the wheel turns, the spoke jumps. A forging, shearing and whiplash effect occurs at the hub flange every time and the spoke hole, which is oversized anyway, is enlarged. A vicious circle begins, the spoke elbow is subject to huge stresses and the material is changed at an molecular level, making the spoke material brittle. The spoke “gives up the ghost” because it simply cant and wont carry on.

DirtyDog: Great advice and description! Yes, zero play in the J bends is the key I think.

My friend has swarn in an oath to obey my ‘first commandment of cycling’ (as stated above)!

Thanks,

GBR & his mate Colin.

@Greenbikerider I’d would love to take the credit but it was copied and pasted from “The Art Of Wheelbuilding” by Gerd Shraner, if you Google it there’s a PDF of the book available online, it might be worth fitting washers next time, see page 41 of the book.

Loose spokes break. Tight ones don’t generally.

get a proper rebuild done. I think is be inspecting the hub flanges too. Make sure they’re not enlarged.

I will help my mate get a quality rebuild done.

As for my own rear wheel (simular to his), my drive side J bends look slightly scratched but not too bad. It’s a good quality build that has lasted me 6 years so far.

But is there anything I can do to my current J bends to further protect/strengthen them (ie, without rebuilding)?

Mavic EN521 rims, Hope Pro 2 evo hub, DT Swiss Revolution black spokes.
GBR.

Dirty Dog nailed it with “too little tension”

+1 for a rubbish wheel build.

It’s quite easy to build an MTB wheel straight in a stand, the rims are so stiff they’ll hide any errors. A tension meter mostly solves this, pinging them will pick out any that are massively out, but isn’t very accurate, I tired it once and getting them all the same reuslted in a very wobbly wheel, using a tension meter get’s it within +/- 2mm before you even start truing, it’d probably be even more accurate with more passes but it’s quicker by then to just true it in the stand.

If the guy in Evans just builds them for other people then he might just be going through the motions of building the wheel, and under pressure to do it quickly. Whereas doing it yourself you very quickly learn why certain things are done certain ways and why each steps important if you want the wheel to last more than one ride (or 6 months).

Try finding an actual wheel builder or learn to do it yourself. Some smaller LBS’s will send them off to a local builder to do rather than doing them in house. It’s usualy some retired roadie who’ll have done thousands of wheels.