sebcast

Hello all,
I'm going to try my hand at wheel building!

A bit of background of why I'm doing this:

• I bought a cargo trike that has rim brakes in the front two wheels and want to convert to disc (more info in this thread, with pics. https://www.bikeforums.net/utility-c...rgo-trike.html)
• The front wheels are 20 inch, and I've found it hard to find already built disc ready wheels in that size.
• I wanna learn

Here's a picture of the existing hub, any ideas what brand this is?
I think I'm going to reuse the rim, so from what I've gathered I just need a disc brake hub with the same dimensions, and then I can plug all the numbers into one of the online calculators to calculate spoke length.

Is there anything else I should be considering? any pitfalls and things to avoid?

thanks!

Andrew R Stewart 

Most disk hubs use medium to large flange diameters, noy fairly low flanges as the current wheel has. What gage are the current spokes? (Kind of looks to be bigger than the way common 2mm/14g size spokes, maybe 105g/2.3mm?) If the spokes are larger than 2mm in diameter then the rim likely also has larger nipple holes too. This might change your planning so check before spending $. The current hub also looks to have a 10mm axle size. True? if so then the replacement hub ideally should also have that size to best fit in the fork drop outs.

As you are learning and this is a cargo bike and these wheels are also your steering control I suggest keeping these wheels intact as back ups if nothing else. Build up a second set of wheels with the combo of specs you need/want. Andy

Those OEM hubs are sure generic Asian made for a price point type. Could be from one of the many "secondary and privet label market" makers that dot the SE Asia region.

ThermionicScott 

What's your plan for converting the bike itself to disc brakes? Looks like the back end has mounts, but the cart part might need some fabrication.

sebcast

yep! that's right.
I found a frame builder near me that's going to braze on some mounts for the front wheels. He said he'd need to laser cut them since they're not standard, but still comes out to just around $150 (considering I got the trike for $300, seems reasonable to have it disc ready for that price).

sebcast

Thanks! this is great info!
I just took the wheel out yesterday and didn't bother to look at it in detail, but now that you mention it, the spokes do seem thicker than what I'm used to. I'll be sure to measure them and the axle size. I'll report back.
And your suggestion to keep these two intact makes a lot of sense. thanks!

sebcast

OK, finally had some time to measure everything (we have a 2 month baby at home, so hard to find the time):
Spokes: 2.3mm
Axle: 9mm
OLD: 100mm
Flange diameter: 40mm

I think I'll just go with regular 2mm spokes for the new wheels, don't want to overcomplicate things for my first build.

Thanks for your help!

Hondo6

You indicated your cargo trike had front wheels (plural). To me, that implies it may carry it's cargo over the front wheels. That in turn would mean the front wheels are substantially more heavily loaded than a single front wheel/2 rear wheel design with cargo space in the rear.

In any case, I have to think that the original manufacturer used 2.3mm spokes for a reason. The reason simply could be cost (many ebikes use 2.3mm spokes, and they may build ebikes too and buy their spokes in bulk). The reason could be engineering overkill to avoid potential lawsuits.

But it's also possible that the reason is that the thicker spokes are needed for max load. A 2.3mm spoke has roughly 1/3 more cross-sectional area (and thus about that much more steel) than a 2.0mm spoke, so they should be considerably stronger.

Dunno.

If it were me, I'd want to run this by someone at a LBS who's familiar with cargo bikes and wheel building before making any purchases. I'm not an expert in either cargo bikes or wheel building, but I'd hate to find out the hard way that 2.0mm spokes weren't quite strong enough.

BCRider

The most handy thing when I was learning was to have another built wheel with the same spoke count and crossings at my side to copy. It's easy peasy to get led astray..

sebcast

Hmm... good point! Glad I asked!
Reading on another thread that regular hubs would fit 2.3mm spokes. Does this sound right?

Rick

I ordered front disk hubs from two manufactures recently. Two of them will work with 2mm or 2.3mm and two of them won't work with 2.3mm. check before ordering.

sebcast

Finally got to lacing the two wheels! Thanks everyone for your comments! you gave me the right information to make good choices.
I ended up going with the 13ga spokes since as Hondo6 rightly pointed out, the weight is on both of these wheels in the front box, so there was likely an engineering decision to have these be thicker. I also followed Andrew R Stewart 's advise and left the original wheels intact and built these with all new components.

Other than scratching the rims in a couple of places (these 13ga spokes don't bend too much!), It was extremely satisfying to do this and learn so much in the process. Thanks all!

hevysrf

I'm wondering if a cross 2 pattern would let the nipples exit the rim a little straighter?