28 or 32 spoke rear - opinions please!

[foz]

When I find time, I'll be building my next set of wheels

Front will be a 28 hole mavic 500 laced x2 with DT comps to a mavic SUP rim.

I'm undecided on the rear though... I have another 28 hole mavic SUP and a 28 hole sachs new success cassette hub. But I also have a 32 hole mavic SUP, which I could find a hub for quite easily. Either way, I'd lace x3 with DT comps.

I weigh 75kg /11st 11lb, and I'm not known for destroying wheels, but I'm not too easy on them either. I've been riding campag neutrons for the last 6 years or so - 24 spoke rear (I think), low profile alloy rim, and they've been fine (I did break one spoke on the driveside, once)

So opinions please - 28 or 32 for the rear?

thanks!

 

[matthew71]

I would go 32, I guess you will not be racing the wheels so I would go for the extra strength

 

[bm0p700f]

the Mavic 500 has a narrow rear flange seperation (NDS flange to centre spacing is very low) if I remember correctly or was that the 503. They may have been the same in this regard. Anyway this means low bracing angles which reduces lateral wheel stiffness. If it is too low it can cause problems. Anyway given you are using a shallow rim that is not know for its stiffness then a 32 spoke is best. A 28 spoke wheel would require a deeper stiffer rim like the CXP33 if you using Mavic.

 

[rusty bodie]

yup, 32s every time. 28 spokers are fine for circus sized people who float uphill!

 

[bm0p700f]

I ride 28 and 24 spoke wheels that I have built and they are stable and I am 80kg too but they are all built with hubs that give good NDS rear bracing angles, and the 24 spoke rear wheel is with a deep carbon rim.

In foz's case 28 spoke would work very well with a different hub.

 

[Donny Dee]

i think at 75kg you could do 28's no bother. SUPs are a very strong rim.

 

[foz]

The 28 hole rear I have now is a Sachs New success, not a mavic. I'm not sure how the measurements compare...

 

[Mike Muz]

Unless you're racing , 32 would be the better option IMO . I'm 78kg and ride 32s 3x with no problems at all . Used to find myself truing up 28s a bit here and there .
Mike

 

[bm0p700f]

Foz you need a stiff rim for a 28 spoke wheel with the mavic 500 hub.
I believe the Mavic 500 rear hub has;
18mm DS centre flange to centre hub
30mm NDS centre of flange to centre of hub.
The NDS bracing angle will be very very low hurts lateral stiffness.

Strengh has nothing to do with this for this hub and 28 spokes I would recommend a 25mm + deep rim. a shallow rim with Race spokes will work but for lighter riders than FOZ unless you want a flexible wheel.

I will give you an example. A build I did with a power tap SL+ hub which has better dimensions (32mm NDS flange spacing) than the Mavic 500 hub (higher NDS bracing angle but still low compared to many hubs), 28 spokes with Sapim Race spokes and a stiff H plus son archetype rim (23mm wide 25mm deep 480g) was just about O.K for the 80 kg rider. If the customer had insisted on using a Mavic open pro (not a stiff rim) he would have had a flexible rear wheel that would have been potentially unstable.

so Foz if that new rim you have a V rim and deep then it will be reliable. If not it is a risk (but may still work). 32H is safer bet but even with a shallow rim (<20mm) and this spoke count the wheel will still not be stiff.

Building a wheel is not just about lashing any old compnents together, they need to complement each other.

 

[Donny Dee]

+1 to the above complimentary kit is essential to a good wheelbuild.