I'm going to build my first set of wheels asap and don't think it will be so bad but my biggest concern is getting the spoke lengths right.
I've ordered extralite ultrarear slx (j bend) and ultra front sl2 (also j bend) and pairing them with chinese carbon rims (24mm, claimed ERD 595mm) - i have my reasons for this and am willing to take the gamble.
So looking at the product pages of the two hubs and the ERD of 595 I put these values into the http://www.wheelpro.co.uk/spokecalc/
front (i plan to spoke these radially, 28H, unless i should do otherwise?)
C=34 (or should i be using 37mm? makes little difference in spoke calc)
D=34 (ditto for C)
ERD=595 or 597
Offset=0 (all the holes in the rim are in the middle and lined up, this means offset=0 right?)
according to these specifications http://www.extralite.com/Products/UltraFront%20SL2.htm
rear (they say i need to do a 3-cross(??) pattern on drive side as shown in a picture near the bottom on this page) and NDS radially? your opinion?)
ERD=595 or 597
and the specs for the rear hub are http://www.extralite.com/Products/wheel ... %20slx.htm
I just want to make sure I'm putting the right values in the right places.
They insist that I measure the ERD using their method (they call it "spoke hole diameter" (except I couldn't get the rubber bands holding the spokes together, instead I got someone to pull them tight and measured that way but things like fingers in the way i'm not 100% confident in this measure). I actually got an ERD of 597 (573 nipple to nipple then 12x2 for the nipples. spokes were fully screwed in but not poking out). I noticed that this makes a 1mm difference in spoke length in the wheel pro.co.uk calculator. I measured it again without someones fingers in the way and kind of got the same (using their method, measuring to just before the nipple and adding the nipple lengths to get the ERD). 597mm again. Should I go with this?
Whats bothering me is that I am getting different spoke lengths (1mm difference) needed using their method on the rear wheel and wheel pro.co.uk calculator. Here is what I am getting for the following.
front (assuming I will do radial 28H)
- extralite site table: --i've contacted them to ask for this as there is no table, and they say they can provide it--
- wheelpro.co.uk: 282.1 if I use 597 and 281.1 if I use 595
(NDS - radial) - or should i NOT do radial?
- extralite site table: it falls in between 595 and 600, so 597 will be either 282 or 283. They're not clear on this.
- wheelpro.co.uk: 281.9 for 597 and 280.1 for 595
(DS - 3 cross????? they've got pictures of what 32H should be and it looks like 3 cross)
- extralite site table: if 595 then 289-290, if 597 then probably 291
- wheelpro.co.uk: 289.1 for 597, and 288.1 for 595
So mainly you can see there is some differences between ERD of 595 or 597, by about 1mm. I'm thinking that 1mm more isn't going to be as bad as being short 1mm, because if the calculations are even off again (shorter than it should be) I could risk less threading coverage in the nipple to the point it becomes problematic.
I want to order asap so if you can make sense of all this, your opinion would be appreciated. as I mentioned it's my first build with EXPENSIVE hubs and spokes but I figure why not? Don't think I could royally stuff anything up if I just take my time and make sure to do everything right.
I'm also going to order some washers, just read something about this adding to the spoke length, so maybe I could do or do without this if I have problems, but they generally seem like a good idea anyway.