Spoke question

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alcatraz
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Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Hi ww's

An older and heavier (90kg) friend on bontrager aura5 wheels (alloy) cracked a rear rim around a spoke hole. (the rim had deformed and in several attempts to true it, caused the spoke tensions to vary so much that a crack developed at a spoke nipple). The hub is fine and I intend to lace a new rim to it. It's 24 hole.

We ordered a carbon rim but now the question is about the spokes.

I use cx-ray equivalent spokes on my own wheels but I'm a light guy @65kg. They have proven very strong and I havent broken one. Very impressed with them.

This rider is not a sprinter and doesn't go over 400w. Would I still be crazy to go with 24 cx-ray's for his weight? I will use dt squorx nipple equivalents (pillar dns) to really have a solid connection there.

My initial idea was to run a step larger crosssectional area spokes than cx-ray on the drive side. However as I look at the tension graph I don't see much more max tension (~10%) as much as I see higher weight (~40%). For this reason I'm inclined to use cx-rays on both sides. (2x/2x).

The original spokes are 2x1.1mm. The cx-rays are 2.2x0.95mm.

Going alloy to carbon on the rim makes the spokes less critical I think. This because a carbon rim doesn't flex as much and doesn't let the spoke tensions fluctuate as much.

Thank you for reading and any comment.
/a

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WinterRider
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Joined: Tue Feb 05, 2013 2:46 pm

by WinterRider

alcatraz wrote:
Sun Jul 01, 2018 4:44 pm
Going alloy to carbon on the rim makes the spokes less critical I think. This because a carbon rim doesn't flex as much and doesn't let the spoke tensions fluctuate as much.
Assuming the carbon rim flexes very little... the hub shell certainly is not to any measurable degree.. then what absorbs the stresses the wheel undergoes? Pedalling.. breaking.. ...potholes et al.

200 lbs isn't a heavy rider.. especially via low wattage. 24H conventionally laced is above the weight a 12-12 rear build can handle long term. Tension balance around the wheel is always critical to spoke longevity.

16-8 would handle 200 in 24H.

by Weenie


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ergott
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by ergott

I would use Sapim Race or DT Competitions.

vejnemojnen
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by vejnemojnen

Go with CX rays or even CX sprint on driveside. I'd even consider Pillar spokes, those generally have good reputation.

btw, 200 lbs is not at all heavy. That's 90 kgs, and any male with sufficient amount of muscle mass and real men's height (185+) can have that mass in a fairly lean state. :thumbup:

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WinterRider
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by WinterRider

vejnemojnen wrote:
Mon Jul 02, 2018 5:34 pm
btw, 200 lbs is not at all heavy. That's 90 kgs, and any male with sufficient amount of muscle mass and real men's height (185+) can have that mass in a fairly lean state. :thumbup:
Agreed.. but the Q wasn't male physiques and opines to such.

Sapim Race.. cost efficient and wind up less than the other mentioned.

12-12 at 2 bills/stones.. means a careful build.. all the ducks in a row. Then your still on the limit.

alcatraz
Posts: 1240
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Thanks for the warnings and info. Had I chosen the spoke number I'd gone with 28 but we are trying to make use of this dt swiss hub.

I'm getting a calibrated tensionometer soon. I feel I need it because I'm going to be using relatively few spokes and a heavier than average rider.

If I can't keep the wheel true I'll switch the drive side spokes to something beefier.

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WinterRider
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by WinterRider

12-12 at 2 stones weight... plastic rim at 530's wt.

DS elbows in is the first consideration.. mostly unsupported by the flange. Tightest fit possible to the flange as the elbow emerges from the hole. Brass washer on the spoke between flange and spoke.. NOT to bend the spoke greatly as you produce the line angle to the rim.

Sapim Strong 13/14's DS 2x. Sapim Race NDS.. laced 1x outside (heads in). Normally I lace the pulling spoke over the pushing NDS spoke.. the 'under' spoke gets same brass washer for fit.. IF needed. Depends on flange thickness .. same for above.

NOT a weenie build w that rim weight.. w this spoke combo plus a 'low wattage' rider it'll hold. Sapim Strong DS will handle the elbow stresses.

This flavor build goes south when the spokes start to shake loose.... 1x NDS work in unison to mitigate such sans fixing the heads w glue. Thoroughly stress relieving the wheel .. trying to get it to move after your finished.. pushing down the rim firmly w axle end on the floor... very FIRM. Try to knock it out.. when one cant it's good to run.

On these low tension NDS traditional builds a good idea to use a locker on the NDS. I like the spoke heads to just show above the recess in the nip.. those couple threads get either weak glue (nail polish) or a blue thread locker. At 2 stones wt.. good idea to apply.

alcatraz
Posts: 1240
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Thanks.

This is an sp hub with 2x/2x lacing config. I'm not sure I can change the pattern.

I will use loctite 222 wickering locker after.

Right now I'm not as much worried about the spoke/rim choice as I'm worried about getting the spoke lengths right. I don't use any fancy calculators. I will true the cracked rim approximately right (5 min job) and then attach the rims together (first one side then the other) and measure the spoke distance left/right and take the average value. Lets say 3-4 DS spokes and 3-4 NDS spokes.

I thought I'd use a spoke with the nipple positioned perfectly and simply hang it out of the rim, measure the difference and subtract that from the original spoke length. (Take average of left/right and 3-4 spoke positions to get it more accurate.) On the DS I'd maybe go 1mm lower than measured because of the spoke stretch there.

I noticed on these rims that the rim wall thickness around the nipple holes varies (spokes aren't all perfect length either). On my previous wheelset (using same rims) I had to move some spokes around. I noticed on some spokes after truing that some spoke threads exit out of the nipple 2-3mm and on others maybe sit flush or 0.5mm below. So I take two extreme spokes and swap them. They come a bit closer together. This is a tip for other amateur wheelbuilders out there.

Rim will arrive in 1-2 days so I can start measuring then. Wish me luck. :lol:


alcatraz
Posts: 1240
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

ergott wrote:
Sat Jul 07, 2018 12:08 pm
https://www.wheelpro.co.uk/spokecalc/
My measurements got me the spoke length 264mm for both sides.

The calculator arrived at 263 + 263.3mm. 264mm should probably be fine then. It even says to round up.

Thanks

Geoff
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Location: Canada

by Geoff

I agree with the other posters. The CX Rays are hella-strong. You might use brass nipples versus alloy for peace-of-mind. I am only 59kg right now and I still build with brass.

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ergott
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by ergott

Geoff wrote:
Sun Jul 08, 2018 11:21 pm
The CX Rays are hella-strong.
Strong and stiff are not the same thing.

by Weenie


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WinterRider
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by WinterRider

ergott wrote:
Mon Jul 09, 2018 1:36 pm
Geoff wrote:
Sun Jul 08, 2018 11:21 pm
The CX Rays are hella-strong.
Strong and stiff are not the same thing.
Agreed.

Yet those terms mean different things to users.

IMO.. strong relates to durability... wheel stays true w no spoke breakage.

Stiff.. you tell me. I read here per the plastic rims.. stiff et al. Yet now I read weight limits on these.. makes me wonder. Like the egg... stiff to a pt and then your done.. :unbelievable:

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