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1) ERD's, The stans site says 591mm for the Alpha, wheelpro.com say 594mm, plenty on google about the them ending up with spokes ~2mm too long using the stans ERD numbers, so the wheelpro ones would appear to be 5mm at least out! Anyone got anything to share?
2) Spoke tension, how much? I know stans recomend lower than most but is this significant enough to be able to guage it by hand? Or should I buy a park spoke tension gauge for £50, which if it saves 1 rim will have paid for itself, and I've 2 pairs of stans wheels to build!
I've a pair at home I can check tomorrow for you-32 3 x rear, 24 2 x front. I think stans numbers were ok.
Tension...I think I read 80kgf instead of 130, and I've been using a method of measuring tension by resonant frequency, I can send you a link, tomorrow.
Weight weenies has some info I think. Some say tension with the tire on as it compress es the rim and reduces tension.
Tension...
Not sure if that's any use to you
Cheers,
I'm going 24 front 28 rear with the alphas, 1x front and 2x rear as I don't trust myself to build completely radial on the front and every other manufacturer seems to put one side radial, with the other 50% the other side radial! So going 2x on both sides seems a good comprimise between weight and strength.
And 32 and 32 3x all round with the 355 29er wheels.
We've been building with Stans rims for a few years now, particularly the ZTR mtb rims but also with Alphas. Having read some of WheelPros advice and using some of our own experiences, we don't trust the ERDs on the rim decals, if in doubt always measure and record them for yourself.
We have 2 x 200mm spokes cut in the shop for this and used in conjunction with Wheelpro's calculator works a treat, it's never let us down so far. Despite what others have said, we feel that spoke length is a crucial part of a good wheel build. We have found the printed ERDs particularly on Stans rims out by up to 4mm on certain rims and this can have a huge impact on spoke lengths.
Good luck with your builds.
Cheers, how do I measure the ERD then? I've only built into Mavic rims in the past and trusted the published ERD's with no issues.
Diameter of the inside plus a nominal ammount for the rim thickness (I'm guessing this is where stansdiffer with no nippleadding ot he thickness, thus spokes end up 'long'?) + the nipple?
Annoyingly most spokes are coming out the same length so if ones wrong almost all of them will be!
We've got 2 x 200mm spokes with nipples glued onto the threads so that the spoke threads sit flush in the end of the groove in the nipple.
Lay your rim on the floor pick a spoke hole (I usually go for 6 or 8 away from the valve), thread a measuring spoke in, then do the same at the opposite side making sure they are adjacent. Pull the spokes tight so that the nipples sit in the rim as they would in a finished wheel and measure the distance between the inner ends of the spokes. Add this measurement to 400 and you've got your ERD.
Despite what others have said, we feel that spoke length is a crucial part of a good wheel build.
Why?
I can't see any reason why perfection could make any difference, a few mm out is fine, as long as the threads don't bottom out and have enough engagement.
Dunno, but I agree, it's a bit like cutting steerer tubes, it makes absolutely no difference if its cut askew with burrs the size of the isle of Wight hanging off it, you just put a spacer over it and hide it. But it'll nagg me untill i tke it appart and file it completely flat with a barely perceptible gap under the top cap! See also: brake mouting bolts too long, cable ties not all facing the same way on hose routeing, headset cups not lined up, building wheels so valvehole and hub logo's line up.cynic-al - MemberWhy?
Stans have already annoyed me, the alpha stickers aren't exactly 1/3 spaced arround the wheel, they're offset so they fall between eyelets (5 spokes, 4 for stickers, 5 spokes 4 for stickers, [b]4[/b] spokes, 4 for stickers).
cynic-al, remember we are building wheels professional (in a business sense) and whilst you may well be right with a few mm either way, I prefer to build my wheels so that the ends of the spokes are as close to flush with the nipple groove as possible. If the spoke lengths are right and the tension is correct it just feels more perfect, maybe that's just me?
From a wheel building perspective, if you are working with the correct spoke lengths, the build is easier at the stage straight after the lace up, the wheel should sit in the jig close to the correct dish, which although isn't the end of the world, is a great starting point.
I agree with the above. I also build wheels as part of my business and that last thing I want to do is spend more time than I need to building the wheel. I therefore thrust no published ERD or hub measurements and do the measurments my self and use spoke calc spreadsheet to calculate the spoke lengths. I then build the wheel relatively quickly.
Also measure the ERD at three or four places around the rim and average. It really helps.
Good we're in agreement there!
OP One point I've read is that you are to tension the wheel with the tyre on.
I just did so and found the tension went down by nearly 50% on fitting the tyre 😮
Oh and here is that tension web page, worked a treat for me after downloading a frequency analyser programme.
http://www.bikexprt.com/bicycle/tension.htm#pitchtable