Wheel building advise please ?

[BADGER.BRAD]

Hello all,

My cassette hub broke today halfway to work (boo hoo) this now means I have two wheels with duff hubs in my bicycle tat collection, I got to thinking I could take them apart and practise some wheel building using these spare bits, Then I thought If I'm going to do this I may as well put some useable hubs in there and put the wheels to use if I'm going to the hassle of rebuilding them. My question is how do I know what type of hub I need to match the spokes? Are there certain measurements I should make? Anything else I should look out for.



Many Thanks all.

 

[andrew_s]

First point: don't get left and right spokes mixed up when you are taking the dead wheel apart.
Also, before taking the wheel apart, have a look to see how close the ends of the spokes are to the base of the screwdriver slot in the spoke nipple. This will give you an idea of how much variation you can get away with if you want to use a hub that requires a slightly different spoke length.

The easy answer is that you need the same type of hub as the broken one, or one that's the same size as the dead hub (eg LX/Deore/XT hubs are all the same).
The more complicated answer is that spoke length (fixed) will depend on the rim (fixed) and the diameter of the spoke hole circle on the hub, and how far out the flanges are from the centre of the wheel (different for left and right). You need to find a hub that has a combination that gives the same length spokes as you have.

I'd suggest down loading spocalc, going throght the list of hubs in it looking for one the same, and if you can't find one suitable, then try out various hubs in the calculator section to try and get spokes the same length (or similar). If you've got pukka Excel that's easy. If you are using openoffice Calc or 1-2-3 or something, you may have to type in the hub dimension each time and it will take longer.

 

[spandex]

I could say the same as andrew and more but I will not just have a look at

House of 3 d

Sorry but I can not find the web site that I downloaded a chart from which has worked many times for me.

 

[barq]

Lots of good advice above, but in addition to that...

I think this might come down to whether you have an easily identifiable and/or very common hub size (which is possible). Search for the technical specs of that make/model online and then compare the specified lengths with measured ones. If that all seems ok then swap hubs like for like. The other alternative is using a different hub and calculating the new spokes (usually sold in 2mm increments). The DT Swiss website has a spoke calculator with common hub/rim sizes filled out.

 

[BADGER.BRAD]

Many thanks for the advise all,much appreciated.I thought it would give me something to play with on these dark nights.I will take the two wheels out later and see If I can find out more info on the hubs.

 

[fossyant]

Daft question - what bit has broken ? The freehub, or are the bearing races goosed ?

 

[BADGER.BRAD]

The bearing races on one and the free hub on the other ???

 

[fossyant]

Spare/new freehub - just need a 10mm allen key ?

 

[jimboalee]

Try to salvage the spokes if the rim is being changed. One can even do a tape-together rim change.
If its new hubs, chances are the newuns will be different, so you may as well build with new spokes the correct size for the new hub.

Easiest way to remove the spokes is with a sturdy pair of pliers. Do not take the rim tapes off first or you will be playing darts with 36 arrows.

 

[hubgearfreak]

I could say the same as andrew and more but I will not just have a look at

House of 3 d .

this one's even easier. i think

http://www.bikeschool.com/spokes/

 

[andrew_s]

I could say the same as andrew and more but I will not just have a look at
House of 3 d

this one's even easier. i think
http://www.bikeschool.com/spokes/

For both of them, you've still got to measure the rim and hub dimensions (accurately!), and type them in.

You've only got to type them in with spocalc too, but it's got a database of loads of hub and rim dimensions so you don't need to measure. If you use Excel, you can just highlight the right hub/rim and click a copy dimensions macro so you don't even have to type, but that bit may not work in non-Excel such as openoffice.

Instead of downloading spocalc, there's also this calculator, which has a copy of the spocalc database in it.

http://vocabforbreakfast.railsplayground.net/edd/

It gives slightly different answers to spocalc, apparently because of java rounding errors.