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PostPosted: Sun May 18, 2014 1:51 pm 
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Joined: Wed Mar 26, 2014 11:46 pm
Posts: 16
Would a 24H front and 24H rear setup be adequate with a set of Light Bicycle 45mm U shape rims on Novatec disc hubs (D711/D712)?
Should they have a particular spoking arrangement due to the more powerful (than rim brakes) discs? LB themselves seem to use Pillar Aero X-TRA 1420.

Note they would be for road use only.


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PostPosted: Sun May 18, 2014 3:06 pm 
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Joined: Tue Nov 11, 2003 9:47 pm
Posts: 1762
Location: Santa Cruz, California, USA
The braking forces from a disc go from the disc to the hub to the spokes to reach the rim and tire. With a rim brake it's only the rim and tire. This why radial spoking is ok on a rim brake.

For a disc wheel you'll need 2x at least. I have seen MTB wheels with 2x on one side and radial on the other but I'd do 2x both sides. There is no performance benefit to radial spoking. A road tire on pavement can get better traction than a mtb tire on dirt and could stress the wheel more under braking.


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Posted: Sun May 18, 2014 3:06 pm 


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PostPosted: Sun May 18, 2014 3:08 pm 
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Joined: Sat Jun 16, 2012 3:12 am
Posts: 226
I imagine if you are light or gentle on wheels then 24h would be fine. I debated but ended up doing 28h (CX ray, Novatec hubs) just for peace of mind. I weigh 170-175lbs, for reference. I only have ~700 miles on these,but they have been drama-free. I would have done 24h if Novatec had a disc straight-pull option (that was available for purchase somewhere).

Oh, and I did 2x everywhere.


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PostPosted: Sun May 18, 2014 4:38 pm 
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Joined: Wed Mar 26, 2014 11:46 pm
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So 2x on 24H front and back should be ok, i weigh ~150lb.


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PostPosted: Sun May 18, 2014 5:30 pm 
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in the industry

Joined: Sat May 12, 2012 7:25 pm
Posts: 1489
Location: Glermsford, Suffolk U.K
I think 24H 2x both both sides will be fine. I have just done so 28 spoke wheels on DT Swiss straight pulls but the rider is fair bit more than 150lbs. I intend to build 24 spoke disc brake wheels I think they will be fine.

_________________
www.thecycleclinic.co.uk


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PostPosted: Sun May 18, 2014 8:58 pm 
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Joined: Fri Jan 28, 2011 8:02 am
Posts: 32
im now building 20h disc brake front wheel. carbon 26"


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PostPosted: Mon May 19, 2014 12:25 am 
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Joined: Sat Jun 16, 2012 3:12 am
Posts: 226
manninen wrote:
im now building 20h disc brake front wheel. carbon 26"


Are you able to lace that 2x? A 20h MTB wheel seems a little crazy, but I wish you good luck :)


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PostPosted: Mon May 19, 2014 10:31 am 
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Joined: Fri Jan 28, 2011 8:02 am
Posts: 32
https://dl.dropboxusercontent.com/u/33080121/myynnis/497.jpg
497g now, bike is now rear disc only and commuter use.

i think it´s going to be 630g´ish with new hub dt comps 2x, i hope.
brake is hy/rd with s500 levers on shortest reach so not much brakepower going on on front


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PostPosted: Sun May 25, 2014 3:35 pm 
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Joined: Fri May 23, 2014 2:04 pm
Posts: 9
edit: started a new thread, too many questions to tack onto the discussion here. feel free to delete this post.


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PostPosted: Mon May 26, 2014 10:38 am 
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Joined: Fri May 23, 2014 2:04 pm
Posts: 9
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/ calculator.

front (i plan to spoke these radially, 28H, unless i should do otherwise?)
A=34
B=34
C=34 (or should i be using 37mm? makes little difference in spoke calc)
D=34 (ditto for C)
ERD=595 or 597
Spokes=32
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?)
A=35
B=50
C=36.5
D=20
ERD=595 or 597
Spokes=32
Offset=0

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

rear (32H)
(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.

thnx


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PostPosted: Mon May 26, 2014 10:58 am 
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Joined: Wed Feb 02, 2011 3:48 am
Posts: 1053
Extralite have just updated their webpage with finished pics of road disc hubs... wow!

Image
69g

Image
145g


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PostPosted: Mon May 26, 2014 3:55 pm 
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Joined: Fri Jan 28, 2011 8:02 am
Posts: 32
such sick hubs.

https://dl.dropboxusercontent.com/u/330 ... .00.11.jpg

finished 20h disc front. 656g. brass. alpineIII

am i correct about this? 24h front hub with radial non disc side. when you brake, most the force goes thru 6 spokes, like 70-80%?


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PostPosted: Mon May 26, 2014 5:20 pm 
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Joined: Tue Nov 11, 2003 9:47 pm
Posts: 1762
Location: Santa Cruz, California, USA
@battler-

When I made my ERD measuring tool (out of two spokes and nipples) I cut and filed the spokes to exactly 250mm and threaded them into the nipples until the ends were flush with the bottom of the slot, not the end of the nipple. It's not too difficult for one person to simultaneously pull both spokes tight and measure the distance between the ends.

I'm not a fan of radial NDS. I have built wheels with that and had wheels built by others. They seem to flex laterally more than wheels built with crossed spokes NDS and on hubs with large countersinks on the spoke holes (i.e. Bitex) they eventually break at the elbows. You can use spoke washers to address that. Same problem exists on radial fronts too, which is why I often use 1x heads in there.


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PostPosted: Tue May 27, 2014 6:49 am 
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Joined: Fri May 23, 2014 2:04 pm
Posts: 9
yeah i did that as well. two spokes onto 2 nipples to the bottom of the slot (where the threading ends) and pulled them together. I got 597. i did it again without someone holding instead just rest it on a table (so fingers werent in the way) and measured from just where the nipple ends on the inside and added 2x12mm, and ended up with 597 again.

i was going to definitely do radial on the front 28H, because the 28H is even overkill as it is, so i figure it will be fine. extralite seem to expect that you will use radial on the front.

i am going to consider doing 3x for both DS and NDS now. but again, extralite tables are different and they seem to expect radial on the NDS.

edit: ok enough faffing around, i'm now confident of the calculators and the ERD of 597 (measured 3 times now) - now i just need to decide whether to going 3x on NDS. or whether radial will do. @eric. most of what ive read say radial is supposed to actually be laterally stiffer than otherwise.

ERD 597

front (radial)
wL=34
wR=34
lD=34
rD=34
shd=2.5
offset=0

spocalc.xls=282.3
dtswiss calc=282.3 (they recommend 283 rounded up)
wheelpro.co.uk calc=282.1

rear DS (3 cross)
wL=35
wR=50
lD=36.5
rD=20
shd=2.5
offset=0

spocalc.xls=289.3
dtswiss calc=289.3 (they recommend 290 rounded up)
wheelpro.co.uk calc=289.1

rear NDS (radial)

spocalc.xls=282.1
dtswiss calc=282.1 (they recommend 282 rounded down)
wheelpro.co.uk calc=281.9

rear NDS (3 cross)

spocalc.xls=293.1
dtswiss calc= 293.3 (they recommend 294 rounded up)
wheelpro.co.uk calc=293.1


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PostPosted: Tue May 27, 2014 10:18 am 
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Joined: Sat Jun 16, 2012 3:12 am
Posts: 226
If it is a 32h rear wheel, just lace 3x/3x. There is not going to be any noticeable benefit to radial nds and if this is your first set of wheels, don't over-complicate things. Radial NDS is slightly better bracing angle (for stiffness), but with so many spokes stiffness should not be a concern here. (It does seem a little odd to buy super lightweight hubs and rims and then offset some of that weight savings by using so many spokes -- buy maybe the wheels would not be stiff enough otherwise.)

As for calculators, the wheelpro one has always worked great for me. Spokes within a couple mm should be OK, though I tend to favor rounding down. Nothing worse than running out of threads before the wheel is up to tension.


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Posted: Tue May 27, 2014 10:18 am 


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