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Had 2 29er rear wheels and had the good hub put on the good rim by the local roadie shop. They used new spokes.
Having never broken a spoke in 20 years I’ve now broken 2 in 6 months. Are inferior spokes the issue here?
Looks like an alloy nipple that’s failed rather than the spoke but hard to tell from the photo.
Not really road or mtb spokes but some are lighter and some are stronger.
If it has been build with alloy nipples just get it rebuild with brass ones
That's a broken nipple, I'd say it's likely to be a build issue but after 6 months the shop may not be interested.
They will be much the same. Broken spokes are often down to lack of tension which allows them to move in the spoke holes at the hub, causing fatigue. A re-true may help but it may be that all the spokes have suffered fatigue.
Stress corrosion failure of alloy nipples, particularly if you've been riding over winter on wet roads exposed to salt. Rebuild the wheels with brass nipples.
Picture looks like a broken nipple, caused by the spoke being too short, I would guess alloy nipple.
Guessing the end of the spoke is flush with the broken nipple? It should extend into the head of the nipple, more crucial will alloy nipples.
I would take the tyre off and check the thread engagement in the nipple
As for spokes I would normally build road and MTB wheels with double butted spokes, aero etc if the customer wishes.
Unless the picture is misleading, those spokes are slightly too short. Especially if using alloy nipples the spoke must extend into the head of the nipple or they are liable to break.
The other spokes except one are flush with the slot of the nipples. This spoke doesn't quite reach the rim.
Alloy nipples are gash.
Should the spoke reach into the rim?
There are no differences between road and mtb spokes (other than in the cases of super proprietary spokes like on some top end wheelsets - mavic used to be bad for that). In-fact, one of the best spokes for building any wheelset (irrespective of type of riding) is the Sapim cx-ray. They're the lightest spoke in the world but with the correct tensioning can be used even in a world cup DH wheel.
And while I agree with the majority of people on here about alloy nipples and correct spoke length, I've got something else to add.
Balanced spoke tension is one of the most important things about building any wheel. At this point, a lot of weaker wheel builders will look at you with a blank stare but it massively affects the strength and longevity of a wheel. The old fashioned way of testing whether it's balanced is by "pinging" the spokes along one side and they should all make about the same pitch of noise, but the more scientific way is to use a tool such as the Park Tool TM-1. It helps you to properly measure the tension to ensure it's in the right range for the rim (all rims have a recommended spoke tension) while you true and tension your wheel.
I built myself a set of wheels in 2009 bringing all the tensions on each side to the exact same value and I've never needed to true them. They've done 2 Alps trips and a decade of abuse in the peak district and they're still within about 1mm of true.
Usually, spoke tension balancing is the Achilles heel of machine built or off the shelf wheels. They work on a less haste more speed model to keep the price down and this is the kind of thing which is put by the wayside. The likelihood is that your previous wheels we're well balanced where the wheels in question weren't and that's why you've blown some spokes. This even tallies with the nipple failures since an unbalanced wheel will mean some nipples are carrying significantly more force than others, leading them to fail quicker.
I suppose my point here is that in addition to fixing the issues everyone else has pointed out, invest in a tension meter and have someone who knows what they're doing show you how to balance the tensions and you'll find that broken spokes (and out of true) will largely become a thing of the past.
Should the spoke reach into the rim?
Yes, in order to come to the head of the slot it must extend into the rim a few mm.
I wonder if that spoke was slightly short or has broken off, or if the rim is out of round there. Have you found the head of the nipple? Is the end of the spoke clean or does it look like it broke?