28h Hole Rear Wheel Sufficient?

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mechanicaldope
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28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

Hi all,

Just got myself a new rear hub for my trail/bikepacking bike to build up into a wheel but just noticed it is for a 28 hole rim. Was intending to build onto an alu rather than carbon rim. Think think that this is going to be sufficient or should I return it?

Cheers.
slarge
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Re: 28h Hole Rear Wheel Sufficient?

Post by slarge »

You'll be fine, maybe just use heavier spokes?
lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

Low spoke count wheels are used for pretty much all applications these days including enduro and DH.
Personally I always build 32h wheels, I run Rohloff hubs so don’t Get any choice.
Higher spoke counts are advantageous in so far as each spoke is supporting less of the rim therefore a spoke breakage causes less buckling.
Spoke and nipple choice, rim and hub quality probably have as much to do with overall wheel strength as spoke count alone. The skill of the builder and spoking pattern are probably the things that makes most difference at the end of the day.
Last edited by lune ranger on Sat Oct 05, 2019 9:24 am, edited 1 time in total.
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mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

The skill of the builder is probably the thing that makes most difference at the end of the day.
In that case I really am in trouble! Never built up a wheel before!
mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

slarge wrote: Sat Oct 05, 2019 9:08 am You'll be fine, maybe just use heavier spokes?
Was thinking of dtswiss competition?
lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

Try and get a copy of Jobst Brandt’s Wheel Book.
I think it’s out of print but when I read it years ago it really helped me start building good wheels.
Heavy plain gauge spokes do not necessarily make wheels that are less likely to break but they are certainly easier to use for a beginner.
IMO a spoke such as DT Competition or SAPIM race are good general MTB spokes. Double butted, strong, and easy to build with.
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pistonbroke
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Re: 28h Hole Rear Wheel Sufficient?

Post by pistonbroke »

I'd be more inclined to use 2mm plain guage rather than double butted, 3 cross obviously. I've recently respoked my Rohloff with this setup as I was getting frequent breakages and so far so good.
lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

The wheel building articles online by Shelton Brown are another great resource.

https://www.sheldonbrown.com/wheelbuild.html

I usually refer back to this when building wheels
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lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

In his book 'The bicycle wheel' Jobst Brandt, says that double butted spokes will be more resistant to fatigue failure when built into a wheel.

This is because spokes break because of the cyclic stress they suffer as the wheel rotates.

As the spoke rotates thru the bottom of the wheel it experiences a reduction in tension.

Butted spokes are more elastic so this reduction in tension is spread over more spokes, each experiencing a smaller reduction in tension.

Wheels are an order of magnitude stiffer than the tyres they roll on, so any stiffness differences will not be noticeable. A wheel built with butted spokes will be able to carry a heavier load before any of the spokes become slack. At this point the rim is no longer restrained and the wheel will be more likely to collapse.
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redefined_cycles
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Re: 28h Hole Rear Wheel Sufficient?

Post by redefined_cycles »

mechanicaldope wrote: Sat Oct 05, 2019 9:24 am
slarge wrote: Sat Oct 05, 2019 9:08 am You'll be fine, maybe just use heavier spokes?
Was thinking of dtswiss competition?
Thats what I'd use... but don't discount the double butted ones (in dt swiss flavour) as they're just as strong and there's the argument (actually evidence IIRC) that double butted actually have a greater fatigue life

Edit: what Lune Ranger said (didn't read before soz).
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Alpinum
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Re: 28h Hole Rear Wheel Sufficient?

Post by Alpinum »

mechanicaldope wrote: Sat Oct 05, 2019 9:24 am
slarge wrote: Sat Oct 05, 2019 9:08 am You'll be fine, maybe just use heavier spokes?
Was thinking of dtswiss competition?
I ride 28 super comp's on DT350 hubs and carbon rims on my short travel susser and it's been good sofar (2 years).
Wheels are still laterally really stiff, but under hard braking or steep climbing I can hear the spokes rubbing/creaking. It's a fun and fast bike so I don't hold back much on descents and don't have to take care. Also more compliant than 32 h, same front rim, same hub, and comp, rather than super comp. At the end of lots of riding there is less fatigue and when the rider is less tired, he rides better and safer and this will ultimately lead to longer lifespan of wheels :-bd :wink:

Yet I did have loads of issues with Easton wheels with 28 spokes. Needed retensioning regularly, soft and unprecise when riding a bit harder, damaged many spokes and also a freehub. I got replacements (3 x, sold with the last replacement) and nothing changed. Similar experience with 32 bladed spokes on a Pacenti rim - some alloy rim/spoke combo just were to weak for the way I ride.

I guess it depends much on how you ride and what rim you choose and depending on how you ride, what terrain, load etc. More with 28 than with 32 h I guess...
lune ranger wrote: Sat Oct 05, 2019 9:37 am In his book 'The bicycle wheel' Jobst Brandt, says that double butted spokes will be more resistant to fatigue failure when built into a wheel.

This is because spokes break because of the cyclic stress they suffer as the wheel rotates.


That's what my wheel builder says too. I don't know how this translates to mtb, but all my wheels have butted spokes and all failures I had were due to riding mistakes at high speeds.
I can imagine a wheel with butted spokes to spread the stress more evenly when one or a few spokes fail, more likely enabling a ride back home.
mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

According to the DT Swiss Spoke length calculator I need 274.9 left and 274.1 right with recommended lengths of 275 and 274. These are with 12mm nipples. And must be black. And DT Competition DB (unless persuaded otherwise).

Trouble is, I don't appear to be able to find 275mm anywhere except one place where they come bundled with alloy nips and for too many of them which I don't want. Internet advise appears to be to either go longer or go shorter... Helpful. In practice will either 274 or 276 be fine?

Also, advise on a good place to get these from would be nice :-bd

Cheers!
mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

Also, the spokes I have removed appear to be DT DBs (assume competitions) but are 278/9mm. I assume there is nothing I can do to reuse these (other than choose a different rim)? The wheel they have come off is brand new so they are perfect. I think the nips are alloy though but don't really know how to tell they aren't chromed brass.
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Bearlegged
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Re: 28h Hole Rear Wheel Sufficient?

Post by Bearlegged »

Always round down, go with the 274s.
lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

Landslide wrote: Mon Oct 14, 2019 7:13 pm Always round down, go with the 274s.
^^ This.

With straight gauge spokes and the correct tools you can cut spokes to size and roll on new threads. It’s not really an option with DB due to the butting.

I’m a fan of DT Proloc nipples that come with a light locking compound in them and help to keep everything in place once the wheel is built.
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mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

Cheers all. 274 it is then.
I’m a fan of DT Proloc nipples that come with a light locking compound in them and help to keep everything in place once the wheel is built
Any idea how this compound holds up once it has been broken and the nipple used again? I am thinking that the nipples I have may actually be brass and I can at least use them again.
lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

Think DT say it’s ok for some readjustment but it wouldn’t survive a rebuild.
If you have Proloc nipples and reuse them they would just be like standard nipples.
I tend not to reuse nipples when rebuilding wheels. I have no real basis for this but avoid it even if i’m reusing the spokes on a like for like rim swap.
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mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

Thanks. Guess it's only a fiver or so for new nips so probably worthwhile using new ones.
redefined_cycles
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Re: 28h Hole Rear Wheel Sufficient?

Post by redefined_cycles »

mechanicaldope wrote: Mon Oct 14, 2019 9:00 pm Cheers all. 274 it is then.
I’m a fan of DT Proloc nipples that come with a light locking compound in them and help to keep everything in place once the wheel is built
Any idea how this compound holds up once it has been broken and the nipple used again? I am thinking that the nipples I have may actually be brass and I can at least use them again.
Brass nipples... then just reuse them. The compound is (IMO) just an excuse for building poor quality wheels... If you get the tensions just right and tuned appropriately (you're trying to find the perfect balance between equalish tensions and) with the lateral and radial true. Then there's no real reasons to be using the lcoking compound at all...

One thing my wheelbuilder teacher (he was a little crap) taught me is (this was good) to throw the nipples in some oil and oil the threads (obviously)... that way you've got as much ease at reaching the tensions with not as much friction.

Hope that makes sense...

Roger Mussons book is the bees knees btw
redefined_cycles
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Re: 28h Hole Rear Wheel Sufficient?

Post by redefined_cycles »

mechanicaldope wrote: Mon Oct 14, 2019 5:40 pm Also, the spokes I have removed appear to be DT DBs (assume competitions) but are 278/9mm. I assume there is nothing I can do to reuse these (other than choose a different rim)? The wheel they have come off is brand new so they are perfect. I think the nips are alloy though but don't really know how to tell they aren't chromed brass.
If they're not brass then around 4 should weigh a gram or so... if brass then they are substantially heavier (around 1g per nipple AFAIR but its well worth it
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

“The compound is an excuse for building poor wheels”

Thanks Shaf :wink:
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Alpinum
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Re: 28h Hole Rear Wheel Sufficient?

Post by Alpinum »

redefined_cycles wrote: Tue Oct 15, 2019 2:21 pm Brass nipples... then just reuse them. The compound is (IMO) just an excuse for building poor quality wheels... If you get the tensions just right and tuned appropriately (you're trying to find the perfect balance between equalish tensions and) with the lateral and radial true. Then there's no real reasons to be using the lcoking compound at all...

One thing my wheelbuilder teacher (he was a little crap) taught me is (this was good) to throw the nipples in some oil and oil the threads (obviously)... that way you've got as much ease at reaching the tensions with not as much friction.

Hope that makes sense...

Roger Mussons book is the bees knees btw
I'd not reuse the nipples. Seems like the wrong place to save the planet/your wallet.

Bathing the components in a certain oil is the top tip. The wheelbuilder's I rely on do that too, so it can't be bad. I think for my everyday/travel bike he even used linseed oil to make them last (corrosion of nipples/spokes/rims).
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Re: 28h Hole Rear Wheel Sufficient?

Post by redefined_cycles »

:grin: :-bd
lune ranger wrote: Tue Oct 15, 2019 3:46 pm “The compound is an excuse for building poor wheels”

Thanks Shaf :wink:
That’s the last time i’m nice to you brother :grin:
mechanicaldope
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Re: 28h Hole Rear Wheel Sufficient?

Post by mechanicaldope »

Right.. All ordered. Black 274mm DT Comps with Black Proloc nips. Let's just hope I didnt muck up the length calculations. Rose bikes BTW were by far the cheapest, even with a substantial amount of postage on top.
lune ranger
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Re: 28h Hole Rear Wheel Sufficient?

Post by lune ranger »

Cool.
Happy building. Take your time and enjoy it.
Take care to check your work as you go. Make sure each set of spokes are laced properly before going onto the next and only make small adjustments to the nips each time.
Good luck
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