Right, I need to get a new rear wheel. I'm skint but thinking that it might be worth paying for DT double butted spokes to save a bit of weight without sacrificing strength (I ride a HT and weigh ~90kg). But then I read somewhere that plain gauge on the drive side is a good idea...I'm confused...help.
Having studied the strength of spokes for a mechanical engineering paper, you probably won't notice a difference. In fact the butted spokes in my testing (although only having 90%of the strength) actually stretch less which provides a more solid drive in the rear wheel. The fact a wheel is built correctly has more bearing on the overall strength.
Thanks - sounds like db are worth the extra £9...
The fact a wheel is built correctly has more bearing on the overall strength.
This.
I'm getting it from Merlin and hopefully they know what they're doing...
build it yourself.
useful,cheaper.
MarkyG82 in "self proclaimed engineer misses various relevant points" shocker!
OP either will be fine.
Having studied the strength of spokes for a mechanical engineering paper
I presume given your other comments you only studied them in isolation (though I'm very confused by your comments about butted spokes stretching less - basic physics shows that can't be so).
Don't get butted spokes to save weight. They do however build stronger wheels (all else being equal - as mentioned, build is more important). There is an argument for PG on drive side, as it will help to reduce the difference in stretch of the spokes on either side due to dishing, but it's outweighed by the advantages of butting (I have normal butted drive side and DT Revs NDS for that reason on one of my wheels, but the difference it makes is marginal).
Thing is aracer, using the "more butted" spokes on ghe DS gives a stiffer wheel...
My conclusion....mosf of this guff does not matter a great deal.
I'm getting it from Merlin and hopefully they know what they're doing...
I bought some wheels from merlin a few years ago, didn't last long 'til they went out of true. LBS (Jackie at Nirvana) straightened them and they never went out of true again.
I bought some wheels off of merlin 5 and a half years ago and have been abusing them every week since and they haven't needed truing ever.
using the "more butted" spokes on ghe DS gives a stiffer wheel...
Laterally stiffer initially, yes. Under heavy impacts they'll become less laterally stiff than if you'd laced them the other way round though...
build it yourself.useful,cheaper.
+1
Just built mine, can't comment on longjevity yet but it's strangely satisfying and addictive turning a pile of spokes, hubs and rims into wheels.
Going to build some for the road bike next (they were origainly meant to be practice before the MTB ones, but the pitch ate it's rear wheel).
build it yourself.useful,cheaper.
Are you sure about the cheaper? Last time I priced it up, buying the individual bits cost more than a cheap pre-build wheel.
What do you need to build a wheel? Do you need a jig or can you improvise?
Ta
I weigh 70kg and have run double butted spokes for the last three years with no problems other than the alloy nipples I originally used going brittle. All nipples now changed for brass ones.
cheaper
hahahaha
An upside down bike and a piece of chalk make a good substitute for a proper jig.
Are you sure about the cheaper? Last time I priced it up, buying the individual bits cost more than a cheap pre-build wheel.
LBS wanted £85 to build a rear wheel onto an existing hub, the parts for 2 wheels form rose bikes cost £85 excluding hubs.
I reckon you could build a pair of hope hoops with any of the options other than Stans for the £310 they sell for in most shops.
Depends on the shop/wheel though, apparently CRC build them on machines now which may/may not be better than handbuilt.
http://pardo.net/bike/pic/howto-001/component-details.html
As long as you have a good spoke key, then you can just use the bike as the wheel jig. Depending on the hub / dropout type you can just reverse the wheel to check the wheel-dishing.
ok.cheaper in the long run.
maybe not cheaper like for like.but if you buy when something's on offer,and aren't set on something too specific.it's cheaper.
no truing costs, ever.factor that in..
a nice ghetto stand is(are?)some forks mounted in a vice.
^ only works for front wheels though 😉
If you are wanting a high end set of wheels with all new bits then just get them built somewhere like Merlin etc.
If you are knocking yourself up some wheels on the cheap with bits you already have then sure have a go at DIY. you can get spokes pretty cheaply if you look hard enough.
Aracer:
You are right that they were isolated from real world use. The principle is correct though. I discussed it with a materials science lecturer and we came to the conclusion that the process of butting the spokes 'compresses' the structure if the metal causing it to be less elastic. So for a given force it will stretch less but ultimately hold less load due to smaller CSA of the material overall.
This is what I found. Whether its correct or not is another matter al together 😀
I discussed it with a materials science lecturer and we came to the conclusion that the process of butting the spokes 'compresses' the structure if the metal causing it to be less elastic. So for a given force it will stretch less
Well I'd love to see your results. Maybe you don't realise what you've got there, as it appears to contradict all known scientific theory. It could be as big a thing as the latest "faster than light" discovery at CERN in terms of a new understanding of the way the world works. You need to get your findings in a major peer reviewed journal, so that other scientists can comment on them (it sounds like your materials science lecturer also didn't realise how existing laws of physics don't adequately explain your work).
I'm impressed at such a major new discovery first coming to light on the STW forum.
aracer - don't be such a c0ck. Marky is right.
As I understand it, butting the spokes plastically deforms them (they're rolled thinner). Yes, it will be weaker, but will have a different stress-strain curve, so the spoke will perform differently to a non-deformed spoke of the same diameter and material.
I reckon you could build a pair of hope hoops with any of the options other than Stans for the £310 they sell for in most shops.
So if you compare apples with oranges you mean?
You can get the Stan's ones for £250ish from many online sources. You could [i]probably[/i] buy all the component parts, albeit with cheaper rims, for £60 more... ergo, pre-built is cheaper!
Getting a shop to build on your existing hubs/rims may not be cheaper, but going to the 'usual culprits' who have online wheelbuild facilities will almost certainly be cheaper than building your own, depends on what you're trying to achieve.
Studied materials science, ir_bandito? Understand Hooke's Law and Young's Modulus? Checked the results of studies into the effects of cold working on elastic modulus of stainless steel?
Ironically, if you check the data provided by Sapim, the PG spokes are actually weaker than the butted ones (and the more butted the better), as the cold working does significantly increase the strength, so you're wrong on both counts!
http://www.sapim.be/index.php?st=products&sub=spokes&category=3961&id=3389&detail=basic
http://www.sapim.be/index.php?st=products&sub=spokes&category=3960&id=3385&detail=butted
http://www.sapim.be/index.php?st=products&sub=spokes&category=3960&id=3386&detail=butted
andyl
just mount the rear on one dropout.
and zipties.for indicators.
edit.doesn't work for 20mm axles.
edit2.nor do 20mm forks work for this.
Aracer is right.
You don't make steel stiffer by cold working it.
schraner says the 'hammering of the spokes compresses the metal'.
not an exact quote,but roundabouts.
besides,the question isn't that.spokes break at the head.not in the middle.
as my nan always says-always use spoke washers.
if you get stans in the sales then they're cheaper.
got some 819s at half price.granted they have machined sidewalls.but I saved 30eu per rim.
The rim brake ones? The bigger issue is that they weigh a ****ing ton!
aracer is correct - if he isnt then the op is heading for nobel prize territory. I'm a materials scientist.
schraner says the 'hammering of the spokes compresses the metal'.
Is Schraner a materials scientist (or any form of scientist)? If Brandt had said it, it might have been worth bearing in mind, however he actually says "The diameter reduction increases spoke elasticity". Of course if you check in the back of Brandt you'll find he's done some testing which directly contradicts Marky's findings.
Oh, and thanks toys - you trump me as I only studied materials science at undergrad level.
well that was my degree, and my masters and my unfinished phd, and I've spent that last 17 years working as a materials scientist. Don't ask me about nursing though.Oh, and thanks toys - you trump me as I only studied materials science at undergrad level.
Don't ask me about nursing though.
Well for that you'd want a medical professional.
Doh!
Mental stress-strain curve in my head was the wrong way round...
Still, I believe I said:
will have a different stress-strain curve, so the spoke will perform differently to a non-deformed spoke of the same diameter and material
So not technically incorrect 🙂
Studied materials science, ir_bandito?
Yup, but not recently. Hence forgetting the details...
[i]This is what I found. Whether its correct or not is another matter al together[/i]
regarding the above, only 3 types of spokes were tested. 1 x PG from DT, 1 x double butted from DT and a piece of poo zinc coated cheap steel jobby.
The steel jobby broke at the head on many tests. ALL the DT's broke alng the length in various places.
Due to this I dismissed the results of the crappy ones. This threw a spanner in the works due to limited data sources. That is probably why my results showed what they did.
Now, I wait the flames for only using a limited number of spokes (10 ish of each type iirc).
I remember reading about some tests made by mike burrows,he said spokes broke mainly(all?) at the head.
In the schraner manual the graphs indicate that they can all take a lot more tension than the rim can.
Still,we've come a long way from the original question.
Db or pg spokes.
I've read 4 or 5 wheelbuilding manuals,they all reccomend db.
that's good enough for me.I've built with both and the db spokes seem to give a better wheel.that's as far as I'm interested in taking it.
aracer,I don't have my copy here,but I'm fairly sure he (schraner)says both things.
njee20,they're not that heavy!I think you can get about 2000 of them in a (metric) ton..