How many spokes?

Im looking at building a rear wheel with a Campag 126mm hub and Mavic Open Pro rims (both yet to source). What s the most common number of spokes of a rear wheel. I commute 90 mile a week through central London so it needs to be pretty hard wearing. Would 28 spokes be too little?

Thanks

Not just about spoke count-you can have a 32h 3 cross pattern, a 36h 2 cross pattern... yes, 28 spoke wheels are weaker but that depends on how well they're built and how heavy you are too. Most common is 32 or 36h 3 cross, and unless you are a big chap should be plenty strong .

I built 32h 4 cross as an experiment and they have been pretty tank-like so far, but some folks don't think 4 cross is necessary or adds much strength, and its more of a hassle changing spokes and trueing.

32h 3 cross pattern, a 36h 2 cross pattern

You can build either 2 cross or three cross but decreasing in cross while increasing in spoke as you are suggesting here is not the way to go. You are making the spokes leave the hub flange at less of a tangential angle by doing this.

4 cross usually used on 48 spoke wheels to keep the spokes leaving the hub flange at a nice angle.

Thanks Greg, im a light chap trying to get my weight down to Contador's for race season, minus the power! So pretty light. Worried that a 28 spoke might take a battering round London and wont last as long as say a 32 or 36. But 126mm freewheel Campag hubs are hard to come across.

Good hand build on a 28 H you'll be fine, go spendy on CX Ray spokes and you can crank the tension right up on spokes for extra strength/stiffness.

CX-Ray's=£150 on spokes for a pair of wheels if 28 f/r.

Use as few as possible!

Ideally I'd go 32 3x for commuting duties (and in fact have). If I was going down to 28 spokes I'd want a slightly stiffer rim to compensate. Say a CXP 33.

Having said that, if you're resonably light (I am not), a well made 28 2cross open pro pair will see you fine. I'd go with a quality medium guage spoke like a DT Swiss competition, or Sapim Race. I have both on self built wheels, and while they are'nt weight weenie spokes, they are both very nice.

My road wheels have 18 spokes. They are as true today as the day i bought them.

London is not Beirut

Anything over 8 is overkill. The need for 32 is a myth propagated buy the spoke industry.

The UCI will be after you if you commute on that

Meh.

My Midge bars are'nt UCI legal anyway....
....or my tyres.