Wheel building help/advice

[shoota]

Hey wheel-people, I have a set of American Classic Race 29 Tubeless that has the rear rim cracking. Everything else about the set is fine so it seems like a waste to not rebuild these with new rims.

I'm looking at the AC's specs and they are:
- 32h
- ERD is 592

https://amclassic.com/index.php/downloads/dl/file/id/34/product/0/wheel_specification_chart.pdf

If I'm understanding wheelbuilding those are the only two things I need to match up and the new rims should go right on with the existing spokes and nipples right? And follow up question, how much leeway do I have with the ERD because I'm seeing several rims with an ERD of 593, can I use those?

[Mark McM]

Yes, number of spokes and ERD are the specs. that have to match for replacement rims. If these match, you can reuse the hub and spokes. You might want to replace the nipples though, especially if the originals are aluminum.

There's a little bit of leeway with the ERD of up to +2mm/-2mm, so replacing a 592mm ERD rim with a 593mm ERD rim should be fine. (Remember, spoke length is based on the rim radius, and diameter is twice the radius, so 1mm change in ERD would only result in a 0.5mm difference in spoke length, and spokes only come in 1mm increments anyway).

[shoota]

Yes, number of spokes and ERD are the specs. that have to match for replacement rims. If these match, you can reuse the hub and spokes. You might want to replace the nipples though, especially if the originals are aluminum.

There's a little bit of leeway with the ERD of up to +2mm/-2mm, so replacing a 592mm ERD rim with a 593mm ERD rim should be fine. (Remember, spoke length is based on the rim radius, and diameter is twice the radius, so 1mm change in ERD would only result in a 0.5mm difference in spoke length, and spokes only come in 1mm increments anyway).

Oh cool! I didn't think of that math and makes sense. So, the +/- 2mm leeway, is there a preferred direction to go if you have to deviate? Asked another way, is it better to go a little over or a little under the stated ERD?

[ColonelJLloyd]

Agree with all Mark has written. Your choice is really a practical one, though. Your criteria (color, width, tubeless, drilling) will whittle down your options quickly.

The Pro Wheelbuilder rim grid (https://www.prowheelbuilder.com/rims-grid) is very useful to help find options. Put 32 in the drillings field and then sort by ERD. Looks like DT G 540 and GR 531 are good, inexpensive options. Not the lightest, but probably comparable to what they would be replacing. Pinkbike says that 32h wheelset weighs 1,459g. I'm a bit skeptical of that.

[NoMoreParagon]

Hey wheel-people, I have a set of American Classic Race 29 Tubeless that has the rear rim cracking. Everything else about the set is fine so it seems like a waste to not rebuild these with new rims.

I'm looking at the AC's specs and they are:
- 32h
- ERD is 592

https://amclassic.com/index.php/downloads/dl/file/id/34/product/0/wheel_specification_chart.pdf

If I'm understanding wheelbuilding those are the only two things I need to match up and the new rims should go right on with the existing spokes and nipples right? And follow up question, how much leeway do I have with the ERD because I'm seeing several rims with an ERD of 593, can I use those?

ERD in general is a very loose concept as it doesn't take into account the nipple head, insertion of spokes etc. What i usually do is take the spoke+nipple combination i plan to use and then measure ERD by hand.i saw differences between ERD published and ERD measured of 2mm easy and that would, alone, throw off the spoke length calculation.sorry to bring the carrier of bad news, but never trust the published ERD!

[muz]

If I'm understanding wheelbuilding those are the only two things I need to match up and the new rims should go right on with the existing spokes and nipples right?

Technically, you also need to match the orientation of the key spoke hole. That is, whether the first spoke hole next to valve stem is to the right or left of the center line.

Most rims will match, but not all, for example Pacenti Brevet will differ from most. The downside of using such a rim is that the spokes will not be parallel at the valve opening.

[ryker]

Oh cool! I didn't think of that math and makes sense. So, the +/- 2mm leeway, is there a preferred direction to go if you have to deviate? Asked another way, is it better to go a little over or a little under the stated ERD?


If the replacement rim has a smaller ERD, you can use nipple washers to take up a little slack.

[muz]

Oh cool! I didn't think of that math and makes sense. So, the +/- 2mm leeway, is there a preferred direction to go if you have to deviate? Asked another way, is it better to go a little over or a little under the stated ERD?

Take a look at your current wheel and see how the spoke end sits in the nipple. If the spokes are a little short, you would like a smaller ERD, and vice versa.

[shoota]

ERD in general is a very loose concept as it doesn't take into account the nipple head, insertion of spokes etc. What i usually do is take the spoke+nipple combination i plan to use and then measure ERD by hand.i saw differences between ERD published and ERD measured of 2mm easy and that would, alone, throw off the spoke length calculation.sorry to bring the carrier of bad news, but never trust the published ERD!

Can I accurately measure the ERD with the spokes in place on the current wheel? Seems like no so if I have to take a wheel apart I suppose I could do that but don't necessarily want to either. (I'm reusing the hubs too of course)

[shoota]

Take a look at your current wheel and see how the spoke end sits in the nipple. If the spokes are a little short, you would like a smaller ERD, and vice versa.

I just looked and I currently can't see any threads on the nipple. I guess that means they're a little on the longer side and I could look at a slightly larger ERD rim?

[muz]

I just looked and I currently can't see any threads on the nipple. I guess that means they're a little on the longer side and I could look at a slightly larger ERD rim?

I am assuming you mean the spoke ends are flush with the nipple ends, not with the end of the slots. In that case, I would say they are perfectly sized. You could go up a few mm in ERD, perhaps 1mm down as well.

Forgot to mention: no alloy nipples if the spokes are a little short.

[shoota]

I am assuming you mean the spoke ends are flush with the nipple ends, not with the end of the slots. In that case, I would say they are perfectly sized. You could go up a few mm in ERD, perhaps 1mm down as well.

Forgot to mention: no alloy nipples if the spokes are a little short.

That's correct, no threads into the nipple. I was already thinking of getting new brass nipples. What should I look for to replace the alloy ones?

[Mark McM]

ERD in general is a very loose concept as it doesn't take into account the nipple head, insertion of spokes etc. What i usually do is take the spoke+nipple combination i plan to use and then measure ERD by hand.i saw differences between ERD published and ERD measured of 2mm easy and that would, alone, throw off the spoke length calculation.sorry to bring the carrier of bad news, but never trust the published ERD!

Actually, ERD does take into account the position and size of the nipple head. That's why its called Effective Rim Diameter, and not simply Rim Diameter. FLO Cycling, a wheel manufacturer, has a good blog post on ERD (https://flocycling.com/blogs/blog/flo-cycling-effective-rim-diameter-and-spoke-length).

https://1.bp.blogspot.com/-ioEKKAqv5kg/WKtNrq0ooSI/AAAAAAAAEHw/bPAx-u3Iyt0BgS_qOBl9EABNqBOib7pzQCLcB/s320/SpokeCalc_ERD.gif

Confusion comes in because sometimes rims are specified by nipple seat diameter instead of ERD. Nipple seat diameter is the actual diameter of the surface that nipples sit upon. When using nipple seat diameter, spoke length calculations have to be adjusted to account for the dimensions of the nipple head. When using ERD, spoke length can be calculated directly. Mavic is an example of a manufacturer that specifies nipple seat diameter.

One of the most common rim measurement tools are Wheelsmith Rim Rods. These consist of solid rods of fixed length, with a head that represents the shape of a typical nipple. These are used to measure ERD to the top of the slot of the nipple.

[Mark McM]

If the replacement rim has a smaller ERD, you can use nipple washers to take up a little slack.

Not all spokes can use a nipple valve. Particularly, V-shaped rims often have a narrow and curved spoke bed, which is not a good match to most spoke washers.

However, some nipples have different thread offsets, so that longer and shorter spokes can be used. For example, these nipples (https://www.universalcycles.com/shopping/product_details.php?id=91289&category=197) uses spokes 2mm longer than standard. Also many 16mm nipples use spokes about 4mm shorter than 12mm nipples.

[Mark McM]

Can I accurately measure the ERD with the spokes in place on the current wheel? Seems like no so if I have to take a wheel apart I suppose I could do that but don't necessarily want to either. (I'm reusing the hubs too of course)

It's not easy to measure rim ERD on a built-up wheel. However, since the rim is toast, you can unscrew a spoke and measure its length, and then work backwards to find the ERD that would work. Loosen all the spokes a few turns before you remove a spoke (but leave the rest of the spokes attached so that you don't lose their positions.

[Mark McM]

That's correct, no threads into the nipple. I was already thinking of getting new brass nipples. What should I look for to replace the alloy ones?

What does "no threads into the nipple" mean? The spokes would have to be far to short to see any threads exposed below the nipples (i.e. spoke threads showing at the end of the nipple closer to the hub).

Muz was referring to look down at the head of the nipple. The end of the spoke will either be below the bottom surface of the slot in the head (spokes to short), between the bottom of the slot and the top of the nipple (spokes sized correctly), or the end of the spoke will stick out above the top of the nipple (spokes too long).

[ColonelJLloyd]

If the spokes are in the perfect position within the nipple currently and you choose a replacement rim with a smaller ERD, I would recommend using double square nipples. I prefer these nowadays simply because I prefer adjusting the nipples while building from that side of the rim, but in the case described above they will offer you just a bit more purchase if your spokes are a touch long.

[oldpotatoe]

If the replacement rim has a smaller ERD, you can use nipple washers to take up a little slack.

Or spoke washers..Nipple washers 'may' work but they gotta match the internal contour of the rim..

[oldpotatoe]

That's correct, no threads into the nipple. I was already thinking of getting new brass nipples. What should I look for to replace the alloy ones?

Sapim 14mm SecureLock nipples in brass...As for the rim, as has been mentioned..take the tension off the wheel, take out the spokes, measure the ERD(I use Wheelsmith rods)..and with hub dimensions..flange diameter(center hole to center hole) and hub center to flange..calculate spoke length and see if your spokes are the proper length..Many videos on how to measure hubs and ERD.

350mm length rods..into opposite holes, measure the overlap and subtract from 700.

[oldpotatoe]

If this is all too 'much', send me the hub and old spokes and drop ship the rim to me and I'll check the spoke length, use new Sapim Brass Secure Lock nipples and build it for you..

$60 labor, nipples are $.45 per.
If I'm understanding wheelbuilding those are the only two things I need to match up and the new rims should go right on with the existing spokes and nipples right?

I'm all for building your own wheels and not 'hard', it can be 'difficult'...Lots to consider when trying to make those 4 variables proper at the same time.
Tension
True
Round
Dish

[shoota]

If this is all too 'much', send me the hub and old spokes and drop ship the rim to me and I'll check the spoke length, use new Sapim Brass Secure Lock nipples and build it for you..

$60 labor, nipples are $.45 per.


I'm all for building your own wheels and not 'hard', it can be 'difficult'...Lots to consider when trying to make those 4 variables proper at the same time.
Tension
True
Round
Dish

Not sure how I didn't see this until now but I will PM you!