my spokes keep breaking

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I do a 20km return commute to work each day on my Specialized Sirrus Comp which is fitted with Alex AT400 rims 700x28.
I was told these were rated for a 100kg rider, when I started in February I was 114kg now I'm 106kg.
Since I started I found if I went over bumps or cracks in the concrete fast I'd break spokes so I chose a smoother path.
Lately I broke 2 spokes on smooth concrete, one straight after the other so I told the bike shop (this was about my 4th time in for broken spokes) and they said because the bike was about 2 years old that the Taiwanese spokes it came with were probly all due for replacing with some better quality European spokes they supply.
So I got them to change all the rear spokes. Today about 3 weeks later I broke a spoke on smooth concrete again, took it easy for the rest of the 4km left and when I got to work and had a look at the wheel the next spoke along broke while I was looking at it.

Is there something wrong here or is it because of my heft that they keep breaking, I asked for heavier guage spokes to be fitted but apparently you can't do that?
Does anyone know of a solution - it will probably be about 3 more months before I fall below 100kg.

What spokes did they relace it with. I had the same problem kinder. My wheels are getting on a bit and the rear would every so often break a spoke, so I took it in got it relaced with double butted DT swiss spokes and everything is great.

If the spokes are good maybe its time to get a different set of wheels. May I suggest something like Velocity deep Vs with some sort of reasonable hub like ultegra for commuting? Should be strong but not light, you're commuting so strength should be important.

What spokes did they relace it with. I had the same problem kinder. My wheels are getting on a bit and the rear would every so often break a spoke, so I took it in got it relaced with double butted DT swiss spokes and everything is great.

If the spokes are good maybe its time to get a different set of wheels. May I suggest something like Velocity deep Vs with some sort of reasonable hub like ultegra for commuting? Should be strong but not light, you're commuting so strength should be important.

Not butted! Straight 2mm spokes and brass nipples only. The problem might be in the soft rims. Alex rims aren't the strongest choice.

Not butted! Straight 2mm spokes and brass nipples only. The problem might be in the soft rims. Alex rims aren't the strongest choice.

double butted are perfectly fine.

If you want to spend money there are plenty of options. I always find it pretty easy to talk myself into an upgrade.

I checked out the alex website and it says the rims (AT400) are double walled single eyelet which makes them a decent strength design.

Are the rims 32 or 28 hole. That would make a big difference. You should have 32 hole rims.

I'm sure the shop would have designed the spoke pattern with strength in mind (three cross).

double butted are perfectly fine.

I don't think they are fine for 114 kg rider. I'm 80kg and I ride and race off-road on butted 2.0/1.8 spokes with alloy nipples. They are quite fine but wheels require some truing regularily.
When I was 90-93kg I was breaking any spokes except 2.0/brass nipples combo. I commuted and rode XC and was very unskilful.

they are 32 hole, and they did relace the wheel with swiss spokes when they last did it.

can it be wrong tyre pressure? I used to set the back to about 100psi but the day they broke I tried 115psi that morning.