help on spoke sizing

Spoke length calculation is based on simple trigonometry and can be derived from first principles. But if you have a calculation tool (like a speadsheet) then this part is done for you. The resulting formula is shown at:

Spoke - Wikipedia, the free encyclopedia

You need to know the hub flange dimensions (either someone has tabulated them or you need to measure them), rim ERD (again this should be measured), type of nipple you will be using and the number of spoke crossings.

I can't do the calculation for you since I don't have those hubs or rim dimensions to hand, and you haven't said how many spkes and what crossings you will use. Perhaps you can tell us what detail in particular has you confused? Is it how to make a particular measurement?

Tommy1 said:

Hi all, i was wondering if anyone could help me, ive been trying use spoke calculators and getting really confused. i have a set of hope pro 3 hubs and mavic reflex rims (tub) ive just purchased and was wondering what the spoke size needed was? there 32spoke. any help would be greatfull thanks.

If you could measure the hub diameter, hole to hole and the flange center of the hub to each flange, I can calc it for you.

thanks for your help tafi, there 32spoke and i think just a 3cross and rim says 12mm nipple, i dont know an awfull lot about wheels i just know a local wheel builder and he said if you get the parts il build them, so basicly ive ordered 2 32spoke mavic reflex rims and a front and rear 32 spoke hope pro 3 hubs but on buying spokes i havent a clue what size.

the dimensions for the rear hub are left spoke side= 45mm right spoke side = 54mm offset left side= 35.5 and offset right side 17.5mm and dimensions for the front hub are left spoke side= 38mm right spoke side= 38mm and both the offset are 34.5mm, i got the information from here if it dosent make sence

http://www.hopetech.com/database/2010%20HUB%20offset%20and%20pcd.pdf

Right...

Well there are varying opinions (from what I can tell) on the ERD of Reflex rims. Seems to vary between 613mm and 616mm. This makes a difference to the ideal spoke length (between 2 and 3 mm). Peter may be better placed to make a measurement or apply professional judgement for this rim.

Ideally all rims should really be measured anyway because there is a natual variability in manufacture.

I would get your wheelbuilding friend to measure them up, do the calculation and tell you what spokes to buy or tell us the measurement.

I don't feel comfortable listing my calculated spoke lengths for fear of giving you the wrong answer based on the potentially wrong ERD. This might change if we can come to a consensus on the ERD. Sorry.

Tommy1 said:

the dimensions for the rear hub are left spoke side= 45mm right spoke side = 54mm offset left side= 35.5 and offset right side 17.5mm and dimensions for the front hub are left spoke side= 38mm right spoke side= 38mm and both the offset are 34.5mm, i got the information from here if it dosent make sence

http://www.hopetech.com/database/2010%20HUB%20offset%20and%20pcd.pdf

I'll let ya know when I get to work.

Tommy1 said:

Hi all, i was wondering if anyone could help me, ive been trying use spoke calculators and getting really confused. i have a set of hope pro 3 hubs and mavic reflex rims (tub) ive just purchased and was wondering what the spoke size needed was? there 32spoke. any help would be greatfull thanks.

FWIW/IMO. That's a really unusual hub-rim combination ... what type of bike are you planning to use the wheelset on?

FYI. I reckon the ERD for a tubular MAVIC Reflex rim shouldn't be that different from a traditional, low-profile tubular rim [~617mm(?)] -- if it's the same, while it may not be ideal, you can probably lace BOTH sides of the rear wheel with EITHER 298mm OR 299mm spokes, whichever is more readily available (by my reckoning, 299.5 on the non-driveside & 299.8 on the driveside ... I usually round down on the calculated number).
[INDENT]You can probably use MY calculations + your spoke calculator to see how those spoke calculators are generally used.
[/INDENT]Ballparking it, you can choose 296mm spokes for both sides if the ERD is 614mm ... 299mm spokes if the ERD is 619mm.

BTW. The flange offset on a front disc hub cannot be the same for both sides ... presuming a 617mm ERD, the disc-side spoke length would be 298.3mm and the non-disc side would be 299.8mm. You could probably use 298mm spokes on both sides if you wanted to.

thanks for ur help all, il get the ERD of the rim checked and il post back on here or the guy building my wheels will probably can tell me. im using the wheels on my road bike for racing as i live in scotland and the roads arent the best so if there good enough for paris roubaix they should be here 😉 so no disc fittings on hubs. thanks [IMG]cdn.cyclingforums.comicon7.gifOpen ↗[/IMG]

Tommy1 said:

thanks for ur help all, il get the ERD of the rim checked and il post back on here or the guy building my wheels will probably can tell me. im using the wheels on my road bike for racing as i live in scotland and the roads arent the best so if there good enough for paris roubaix they should be here 😉 so no disc fittings on hubs.

Okay. I'm confused by what you wrote ... but, it isn't the first time someone wrote something that I found to be confusing.

Are you now saying that the hubs are NOT disc-capable OR simply that you aren't planning on using discs?

Do you know that a REAR disc hub is designed for a frame whose rear dropout spacing is 135mm whereas the typical Road frame has 130mm spacing?

If the hubs do not have disc mounts, then you provided the wrong PDF file.

If you are having a wheelbuilder lace and true the wheels, then why did you want to know what length spoke to use?

If you want to know what type of spoke to use, well almost everyone who populates this Forum will tell you to choose/use double butted spokes ... having advised you of the conventional wisdom, let me tell you that it is MY belief that a wheel built with straight 14g spokes is better.

As far as using tubular tyres on rough roads, I think you are asking for a lot of heartache and a quickly diminishing bank account ...

Tubulars have a lot less tread than almost any other tyre you have used in the past ... total mileage is low. After ~2000 km, remove the rear tyre and carry it as a spare ... move the front tyre to the rear, and mount a fresh tyre on the front.

PRE-stretch your tyres before you glue them -- the first time you mount a sew-up/tubular tyre, you will swear that you were sold 650c tyres.

The MORE you pre-stretch the tyres, the more glue you will need when mounting the tyres.

From day one, you'll need at least ONE extra tubular tyre (also, pre-streteched BEFORE THE RIDE) that you will want to carry on your rides ...

And, you'll probably want a SECOND PAIR which are ready to go ... so, figure 3 tyres as the minimum, and having 5 tubular tyres isn't unusual -- yes, you should allow for £250+ on tyres right out of the box.

Usually, people stretch new tyres on older/'spare' tubular rims -- I've found that you can also use a 700c clincher rim for prestretching tyres, too.

Good luck!

BTW. If the hubs are typical, low flange hubs then you'll want something like (but, not necessarily!) 16-298mm for the driveside, 16-299mm spokes for the non-driveside, and 32-300mm spokes for the front wheel.

Judging from the measurements Tommy provided, he is using a Hope Pro 3 "Mono 130" It is for a 130mm rear end and has no brake rotor mount.

Tafi you are correct thats the hubs im using, and there road bike hubs so no discs, not sure where that came in about, there just going to be used as a racing wheel only so wont be getting used everyday but thanks alfeng il get some spare tubs just incase.

tafi said:

Judging from the measurements Tommy provided, he is using a Hope Pro 3 "Mono 130" It is for a 130mm rear end and has no brake rotor mount.

Oh, my bad!

Thanks for the clarification ...

I was confused by the diagram of a disc hub at the top of the PDF file.