hillsbreakme

Hello all I'm taking a crack at building my first front wheel and it's not going well at all. The spokes seem too short, after I laced the wheel I started tightening the spokes...only to find they became super tight with 1/2 thread still exposed outside the nipple. In fact I could barely get a lot of the nipples on at all. This is especially discouraging because I double-checked spoke lengths before I bought them.

Equipment
Sun CR-18 700C rim, ERD 612
Shimano Tiagra HB4500 front hub, 36 hole
Hub dimensions - centerline to flange 35.8mm, flange diam. 38mm, spoke hole 2.6mm

I used two different spoke calculators and they both said use 298 mm spokes. I don't know what to do at this point, I can only guess that some manufacturer data is incorrect, but I'm probably doing something stupid is more likely. Any ideas would be appreciated.

mechBgon

Maybe the ERD's not really 612mm.

Sixty Fiver

Published data on the CR18 is 611 ERD.

Ran your hub numbers and got 297.4 for a 36/3 and 292 for a 2 cross.

It is always best to measure every component regardless of published data since this is very often incorrect... just built up a set of Sun Rhynolites and the published data was out by quite a few mm. I was using older rims so it is most liklely that even if the info was correct it was for a Asian made rim and not the old US made rim.

Sixty Fiver

38 and 35.8 are standard Shimano front hub dimensions.

Shimagnolo

Do you have a spoke ruler, and have you measured the spokes?
The last time I built a pair of wheels, a (formerly) reputable source from which I ordered three different lengths sent me an order with *none* of the spokes in the length I ordered.
Some were too long, and some were too short.

Sixty Fiver

Maybe your spokes are the wrong length... if you bought them at an LBS it is more than plausible that they accidentally gave you spokes that were the wrong length.

Always measure everything yourself.

mrrabbit 

Front = 297.61 @ 297.00

Rear Left = 296.28 @ 296.00
Rear Right = 294.61 @ down to 294.00

Those should be your measurements for 3X. Grab a spoke ruler and see what you got. It it matches - checking your crossing as you are lacing.

=8-)

hillsbreakme

Thanks everyone. I don't have a spoke length tool but I used my tape measure, they are spot on 11 3/4", 298 mm (measured from the underside of the bend). I used "the bicycle wheel" as a guide, using the standard 3-cross pattern, I think I got the lacing right (checked it against my road bike), but something else must be very wrong.

I also just checked the ERD, to where I thought the tops of the nipples would be, and I got 609mm. That's pretty close to 612, so I think Sun's ERD is correct.

hillsbreakme

Here's the flunkie, if you can't see the lacing good enough I can probably take a better one.

laura*

I think you've built it 4 cross. It looks like there's a first crossing right at the hub within the flange diameter.

My math says that 4x needs spokes 6 or 7 mm longer than for 3x.

It might be useful for you to take a close up picture showing the lacing near the hub - take the photo to include the outermost crossings.

Sixty Fiver

That is a 4 cross wheel... I don't even need to look at the hub to recognize the pattern.

You did not count the cross that happens right at the hub and went 3x from there to make it a 4x.

hillsbreakme

more photos

Sixty Fiver

Once again... you built a 4 cross wheel.

Look closely at the hub and note that when the spoke leaves the hub is crosses the spoke right next to it and from there you can count 2 more crosses before it makes one more cross and interlaces with it's mate to make that 4th cross.

hillsbreakme

So the lacing example in "the bicycle wheel" is a 4-cross pattern? Would have been nice if they explained that.

Thank you though! Because I can now stop beating my head against the wall and go fix it.

laura*

The good news is that you only need to take the wheel half apart to fix it. Just undo the outer spokes (ie heads in) and reinstall them not as far around the rim. All the inner spokes can stay attached.

Hmmm, the next time I'm at the bike co-op, I'll have to find 36x3 and 36x4 wheels and look at the patterns...

digibud

My copy of The Bicycle Wheel is from 1981 (first edition $9.95). Part II on page 83 lays out the building of a 3x wheel. The three crossing pattern is best seen on page 100. Following a black spoke you see it going over two spokes and under one, or under two and over one depending on outbound or inbound spoke. If your spokes were bought with a 3x pattern length just pull them out and start over again.

Sixty Fiver

I probably build more 4x wheels than most and deal with a lot of vintage English bicycles where they often have a 40 spoke / 4 cross rear wheel and a 32 spoke 3 cross front wheel.

The key to identifying a 3x and 4x is that the interlaced spokes on a 4x sit much closer to the hub because of the tighter angles while a 3x has it's interlaced spokes closer to the midpoint between the hub and the rim.

Most people do not see that many 4x wheels and they are uncommon on modern bicycles as most are 3x... Kuwahara used 36/4 wheels on their 1980's MTB's and my daughter's Norco road bike has a 36/4 rear wheel and a 36/2 up front.

This is a 40 4 cross wheel that I re-built for a 1946 Rudge roadster...

Sixty Fiver

36 4 cross on my daughter's rear wheel... you can see how the interlaced spokes cross very closely to the hub with this lacing and one can see the bigger gaps between the 2 pairs of drive and non drive spokes.

The front wheel is 622 with a 36/2 and the spacing between the spoke groups is pretty and as it is a smaller 520 wheel the spokes drillings are spaced closer together.

hillsbreakme

I'm afraid I am not that good at this wheel building thing. I re-laced the front wheel by removing only the outbound spokes, and now I think I have a 3-cross pattern (there are 3 crosses on spokes attached to the same flange). The problem is the spokes are now too loose. In fact the spoke threads are coming through the nipples and the spokes are not tight at all.

hillsbreakme

No comments on my continued follies but I think I jumped the gun on the spokes being too loose. A couple of them did move past the end of the nipple but only by a little and the tension firmed up after that. It's looking pretty good now and I'm starting the truing process on the front wheel.

Kimmo

Heh, this arvo I was lacing up a wheel; got one side done before I realised I'd gone 3x when the spokes were for 4x...

Sixty Fiver

I have been building wheels for a long time and I still have "those days".

hillsbreakme

I'm working on the rear wheel now but I'm starting to wonder if I did something wrong when tensioning the wheel. I noticed the drive side spokes building up tension fast compared to the left side, but I have the right side spokes tensioned to roughly 100 (21 on my tension meter), and the left side spokes barely have any tension at all. Most seem to read around 10 on the meter with some less! Is there a minimum tension for the left side spokes? I know they are supposed to be less than the right side but I have no idea how much less. This wheel is close to final truing and I am getting worried.

mrrabbit 

Objectives For Rear Wheel:

After stress relieving the wheel...

1a. Drive side tensioned to approx. 110 kgf on average. (24-24.5 on TM-1 for 2.0mm spokes)
1b. Wheel is properly dished - rim centered between the lock nuts of the hub.
2. Wheel trued.

...in that order. Notice I said nothing about the non-drive spokes...your non-drive side is done when the drive side is done with the wheel dished.

=8-)

dabac

You're kinda answering yourself here. Driveside spokes go as tight as the rim manufacturer / wheel builder think it prudent, non-driveside go to whatever the dishing of the wheel allows.

Depends on the hub. Some hubs will only give you 50-something % of DS tension. Most I've built have been in the 60-70 % region.

That's a bit low. 110 or slightly above is some sort of general recommendation.

OK, that's too low. You can bring up DS tension some more, and check your dishing / i.e. if the rim is centered between the locknuts. If it is centered/dished correctly and you still have that mismatch there's something funny going on. Maybe someone has accidentally shifted axle spacers around?