Wheelbuilding / Wheel Building / Wheel build help

I’m going to try and build my first set of wheels, but the set I need at the mo are a 20” pair for a folding bike - is it a terrible idea to try and build a 20” set as a first go?!

If not, they’re for a Dahon Mu Uno folder, 120mm spaces at the back but I think 10mm axle? Want fixed gear at the back so was thinking of the Surly Ultra New hubset but I’m not sure they’ll fit. Also have no idea what 20” rims are good - only need braking surface on the front wheel.

Basically I have no idea what I’m doing and the search didn’t throw up any 20” fixed builds! Any help greatly appreciated!

is it a terrible idea to try and build a 20” set as a first go?

No. Given the likely component choices, small wheels have much more latitude for build errors while remaining usable than large ones. Just don't try 36H 4X om a 20" rim unless you know what you're letting yourself in for.

Ooh. Go for a brakeless specific "aero" profile rear rim. They look so good

Something like:
https://www.sourcebmx.com/Mobile/en/Alienation-Skylark-rim/m-m-27600.aspx?awc=6079_1535977052_5ebb59e463608101b19a00ee2d00995e&utm_source=affiliate&utm_medium=affiliatewindow&utm_campaign=UnitedKingdom

They can get pricey (for BMX rims) though

Good to know, cheers!

Yeah that does look good! Need to be careful on width though as want to squeeze guards in with a 1.75 tyre. Was thinking Halo Sub-4 rims might be good as they can be bought with or without braking sirface

I have an Uno running 2.sonething maxxis dth tyres. Got some guards from AliX that work perfectly with them. I'll post up measurements and links when I'm with the bike later

Ah man that would be so useful thanks!

So I'm not sure if the frame for your Mu Uno is the same as my Sport Uno but I'm running Maxxis DTHs 2.2 (56-406) on quite skinny rims. I couldn't be bothered to take the tyres off but external rim widths are front = 19mm rear = 21mm. The tyres ended up measuring out to 53mm each. This leaves about 5mm of clearance either side at 60psi (I've had them up at 80 before with no issues). I'd imagine they might get too wide on a wider rim. So maybe better to go lower on tyre width.

These are the 60mm guards I ordered:
http://s.aliexpress.com/Yju2QNRn?fromSns=C

Apologies for crappy phone pics

Edit: seems like that AliX link doesn't have the 60mm version on offer anymore/atm. There's a 45mm version though.

4 Attachments

That’s super helpful, thanks so much for taking the time. One last question if you don’t mind - what rear hub have you got in there? Cheers again!

It's whatever came stock with the bike judging by the Dahon logo on the rim. (I got it 2nd hand) 28 spokes, single side freewheel.
28h is probably a good way to go.

Check your spacing, my lock nuts measure out to 115mm.

1 Attachment

Cheers, now for the hard part!!

From my experience of building small wheels is that you need to get the cross pattern right in order to get the nipple to line up especially if the rim has eyelets. It's fiddly enough getting your spoke key in and out but if the nipple angle is wrong then you'll have a harder time turning them. Also with a shorter length you may need to pre-bend the spoke before you can put the nipple on it which can feel like a no no when it's your first wheel build. And then the question of cross brace or not to cross brace.

Not trying to put you off but just trying to make you aware of the issues that you will more than likely encounter.

you need to get the cross pattern right

As I intimated earlier, maximum number of crossings in the regular wheel building guides assume the ERD is many times the flange PCD. You can't build little wheels with this many crossings, but on the up side you can cut the crossings compared with big wheels and still have the spokes close to tangential to the flange pitch circle. If in doubt, make a drawing before you start to see what it's going to look like.

On a few occasions I have a laced up a small wheel and just as I start tensioning I realised that the nipple angle wasn't going to work so I then took apart a 3-cross pattern, trimmed the spokes and then re-laced it 2-cross. Sometimes from 2-cross down to 1-cross. Yes, more tangential tends to be stronger but if there is a risk of losing thread engagement or the nipple breaking that's even worse. But then the ones I built up (there were a lot of them) were large hub motors with 13g spokes laced to 20" rims.

the question of cross brace or not to cross brace

If you mean interlacing, that's a question on big wheels. There's no way I'd either want or need to interlace on little wheels.

Well, I learned this the hard way by over bending the spokes and scratching the rim in the process. Never again. But then you do tend to remember things when you learn the hard way.

I've just seen that mine is also Mu, not Sport.
I've been tempted to go fixed in it for a while but I reckon it gets battered enough as it is.

Let us know how the wheel build turns out, what front hub are you using?

Looking to chuck a front wheel together, if I buy something like this,

and build it radial, chances of the flanges cracking before noon would likely be...?

It'll crack before you get it up to tension :)

I'm building a new touring bike and I'm going to try my second wheelbuild. I've bought rims and hubs. Hopefully I haven't gone too far wrong but would appreciate it if anyone here can double check and make sure I'm not doing anything stupid! I'm thinking I'll do a 3 cross build.

Pacenti CL25 700c 32h

ERD = 607

Novatec D791SB (Front)

Left flange PCD 58mm
Right flange PCD 45mm
Left flange to centre 21mm
Right flange to centre 36mm

Novatec D792SB (Rear)

Left flange PCD 58mm
Right flange PCD 49mm
Left flange to centre 34mm
Right flange to centre 21mm

I've plugged the details into a few different spoke calculators and I'm getting slightly different numbers using Roger Musson's calculator compared to the others I've tried.

Hub Novatec D791SB, front
Rim Pacenti CL25 700c
Spokes 32
Crosses 3
Spoke length left 293.3 mm
Spoke length right 296.7 mm

Hub Novatec D792SB, rear
Rim Pacenti CL25 700c
Spokes 32
Crosses 3
Spoke length left 294.5 mm
Spoke length right 294.6 mm

Roger Musson

Front

        Left    Right

Spoke lengths 292.8 296.4
Spoke head clearance 2.4 1.4
Spoke entry angle 5.2 4.0
Tension 100% 59%

Rear

        Left    Right

Spoke lengths 294.2 294.2
Spoke head clearance 2.4 1.7
Spoke entry angle 5.2 4.4
Tension 62% 100%

Before doing the Musson calculator I was looking at black Sapim Race spokes with brass nipples: 16x 297mm, 16x 294 and 32x 295mm. Do I need 293mm instead (following RM's calculator) and do I want to round up or down with spoke length? Also to get those specific lengths I've ended up looking at a seller on ebay. Is £47 a good price for those spokes with brass nipples? Are they suitable spokes?

Cheers!

Sadly I think you are probably right.

Drum brake front hub - do I need to use the same nds lacing pattern as with disc hubs?

do I need to use the same nds lacing pattern as with disc hubs?

You need to aim for as close to tangential as possible. As the flange is big, that might not mean as many crossings as a disc brake hub with smaller flanges, depending on the spoke count. 3X for 32h or 36H should be fine.

Thanks, but I meant this stuff about heads in/out:

I meant this stuff about heads in/out

This seems to be the subject of holy wars. Pray to your god(s) and let your conscience guide you, but in practice it won't make any difference.
The argument for outbound-pulling (as shown in your diagram) is that the spokes which experience the highest dynamic tension have the best supported bends.
The argument for inbound-pulling is that dynamic tension changes from torque transmission in interleaved wheels tend to pull the outermost crossing away from interference with the RD pulley cage or disc brake caliper.