Wheelbuilding / Wheel Building / Wheel build help

Remember the golden rule - one extra mm on the tyre height counts as one extra spoke in wheel toughness.

It's not a golden rule. Tyres help to cushion impact which is only rarely the cause of spoke breakages... more often spokes die of fatigue and a tyre doesn't do much there.
Fatigue is the number of cycles of load-unload... the higher the number (mileage) and the higher the load (weight per spoke) the quicker they will fatigue. If they are lacking tension they will move a lot in the flange and they will die a lot quicker.
There is also a stiffness issue when you reduce the spoke count, which a tyre cannot address

There is also a stiffness issue when you reduce the spoke count, which a tyre cannot address

Although 46mm tyres on a 20mm rim are going to squirm about so much you won't notice that the rim is moving from side to side too :-)

The 46c Specialized slick doesn't squirm on standard rim and 30 PSI.

Witch craft? or must all books from Einstein to 50shadesofgrey be re-written.

Although 46mm tyres on a 20mm rim are going to squirm about so much you won't notice that the rim is moving from side to side too :-)

Isn't the tendency these days to have very narrow rims? Is everybody doing it wrong?

Slick up to the 46c Specialized (>30psi) runs excellent on standard rims (RS11&thelikes) - the Kojak 35c slick fails on steep velodrome banking at 30psi on R500&thelikes rim.

You can CX with 33c knobbies on standard rims, but you need to inflate them more than you enjoy to keep them from squirming in the grippy cornering on grass. Wider than standard rims would help you here.

You could go up to a 28mm external width rim with 28mm tyres. Assuming you're looking at 28C road tyres and 38C knobblies (not really CX, as they are too wide for UCI racing), you should be alright with 28mm rims. Going too wide on the rims with knobblies can be troublesome because the tread design will probably have been designed for a more rounded tyre profile. Past about ⅔ of nominal tyre width, you're getting experimental

If you want to use 28-38 mm tyres, I'd say you want a touring rim, something in the Mavic range, something like 719. If you are on discs there is even more choice of lighter rims

Thanks guys, I'll be running discs so will have a look around at various options.

Isn't the tendency these days to have very narrow rims? Is everybody doing it wrong?

I don't know what discipline you're talking about but we're definitely seeing wider road rims.

Apparently the RS11+46c slick left the 'UCI-CX' dudes in the gutter in this terrain https://dl.dropboxusercontent.com/u/25868243/2014-06-01%2010.38.18-4.jpg

We're not concerned with spokes bending sideways, since that only happens when you have a stick through the spokes and your problems are about to get much bigger. Rims move to one side under load, and it is spoke stiffness (resistance to being stretched, not resistance to being bent) which opposes this. Within the elastic strain region, the resistance of a spoke to being stretched more is pretty much the same regardless of how much preload it is carrying.

Yes, most of my earlier long explanation to AngelD was about how spokes feel when you push them with your hands, based on trying to make sense of 'flex' in the context of individual spokes. It's a different thing to how the wheel as a whole behaves in use, as even when the wheel flexes, individual spokes remain straight and just stretch more or less. Sorry if that was confusing.

Can anyone find the ERD of this rim anywhere? Would prefer to buy spokes at the same time as the rim.

Edit - Catalogue suggests it's 600, sound reasonable?

Can anyone find the ERD of this rim anywhere? Would prefer to buy spokes at the same time as the rim.

Edit - Catalogue suggests it's 600, sound reasonable?

Sounds reasonable... most Ambrosio rims are around 600 and have a similar profile

The Ambrosio site shows the Pulse as 'renewed' with a slightly different profile to that on Bike24's product page. I'd be inclined to wait for the rim to arrive, just in case Bike24's stock is old (hence the 27% discount). Probably 2.5mm difference in ERD, which might make the difference between spoke lengths.

my take at the asymmetric wheel design was a 28 dt revolution spokes with 2X ds and 1X elbows in nds. I haven't tried it yet, and I have no way to compare back to back.
It was fun to do though and though advantages are probably diminutive I just hope it's not a totally stupid design.

I was after the lightest, cheapest wheelset I could find (student on a budget) for mainly summer use, also a bit of racing and going up alps this August. Found these from superstar (http://superstar.tibolts.co.uk/product_info.php?cPath=77&products_id=520) however the hubs are discontinued so started looking around for alternatives at a similar price and weight. I've narrowed it down to this build, I'd welcome any improvements, all weights/prices are for a 20/24h set up.

Have a look at Soul 2.0 wheels. Quite similar spec and price.

They build theirs with brass nips DS.

I was after the lightest, cheapest wheelset I could find (student on a budget) for mainly summer use, also a bit of racing and going up alps this August. Found these from superstar (http://superstar.tibolts.co.uk/product_info.php?cPath=77&products_id=520) however the hubs are discontinued so started looking around for alternatives at a similar price and weight. I've narrowed it down to this build, I'd welcome any improvements, all weights/prices are for a 20/24h set up.

It's what I call a crap build, suitable to someone who weighs 55 Kg and not very powerful. The Stans are not very stiff and not very strong either ( have to be built at a max 120 KgF tension) and paired with only 24 Revolution spokes will build a snakey rear wheel. This in turn will result in the spokes working loose and breaking... my guess is you can get 500 miles out of them before they start popping
Don't be obsessed about the gram at your age, leave that to mamils with 6 figure salaries.
Swap the Stans for Archetype and the rear spokes for Dt Competition and you'll have a nice set of light wheels

Even on the most charitable view of your error bars (±5 in the lsd of 194.5625), you think DT make spokes to a precision of about 3ppm? That would require them to hold the diameter of the thin section within ±2nm, which is about 7 atoms of iron.

Even on the most charitable view of your error bars (±5 in the lsd of 194.5625), you think DT make spokes to a precision of about 3ppm? That would require them to hold the diameter of the thin section within ±2nm, which is about 7 atoms of iron.

That's just a number spat out by an equation I based on the weight of 64 spokes, obviously it's not accurate

Obviously.

I'll be leaving then

It might be more economical to spend £20 less on each rim and invest in decent tyres.

It's what I call a crap build, suitable to someone who weighs 55 Kg and not very powerful. The Stans are not very stiff and not very strong either ( have to be built at a max 120 KgF tension) and paired with only 24 Revolution spokes will build a snakey rear wheel. This in turn will result in the spokes working loose and breaking... my guess is you can get 500 miles out of them before they start popping
Don't be obsessed about the gram at your age, leave that to mamils with 6 figure salaries.
Swap the Stans for Archetype and the rear spokes for Dt Competition and you'll have a nice set of light wheels

I've read that the rims are pretty strong, I've got mates who uses them for CX and they've served him well. How about DT Comp spokes all round and 24/28? I'm 68kg, 6'3 if that makes a difference and used to mountain biking so sorry for my ignorance

Yes, most of my earlier long explanation to AngelD was about how spokes feel when you push them with your hands, based on trying to make sense of 'flex' in the context of individual spokes. It's a different thing to how the wheel as a whole behaves in use, as even when the wheel flexes, individual spokes remain straight and just stretch more or less. Sorry if that was confusing.

Thanks, I think I'm starting to get it.

I think it's a little confusing as I'm getting explanations from 3-4 people, all trying to comprehend my statements and questions which are using the wrong language to start with!

Reading Jobst Brandt, but it's a little technical and not an easy read.

CX you aren't doing 50km/h round corners leant over at 45 degrees; different level of forces at work in different directions.

Good point, I was thinking more ploughing over CX rock gardens etc, I guess its a different kind of strength

I'm 68kg, 6'3

Are you a twig?! ;)

Seriously though, you want light: the SL versions of those hubs you mentioned, search ebay. then kinlin tb20 for rims, there tubs though, but will ultimately lead to a lighter wheel compared to clinchers, plus they're 400grams, if you want clinchers though, stans 400's, the stans sponsored pro's and cx'ers all use these over the 340's, for a reason I imagine.

Then for spokes dt swiss revolution front and rear non-driveside with dt swiss comp driveside

My Stan's Iron Cross CX rims were soft as cheese, horrible rims to build and went through 3 of them before binning them altogether.