Pacenti Rim Wear Indicators?
 

Does anyone know if Pacenti SL-23 rims have rim wear indicators and, if so, what they look like?

I picked up a couple of used wheels today mainly because I wanted the hubs. They came laced to first generation SL-23 rims that had some wear on them. I've ridden rims with more wear, but I don't know how much wear these have on them. Near the middle of the braking surface there are two parallel grooves on all 4 surfaces (the 2 on each wheel) that are maybe a 1/4 to 1/2 inch apart. Are these the wear indicators? I hadn't seen 2 parallel grooves as indicators before, but I couldn't figure how else the previous owner would get such nice parallel grooves on both sides of both rims (unless he/she tried braking with no pads in the holders or something - but that didn't seem to be the vibe I got).

If they are wear indicators, I can use the rims until they're gone, right? Can't say I've used wheels that have had them before.

thanks

i have gen 2 and they have 2 small circle shaped indents for wear indicators. sorry this does not help much

Keep an eye on the spoke tension and the rim around the spoke holes. IIRC these rims had spoke caused cracks sometimes. Not that other brands didn't as well though. Andy.

Thanks, I didn't see any cracks when I looked them over. Right now the wheels (or at least the rear) is going on a bike that's going to be on a trainer for the next couple of months anyway, so I have no immediate worries about the brake track, but eventually I'm going to ride outside again (right now my main time to ride is pre-dawn, and it will stay that way even as the weather warms), so I'd eventually like to get an idea of whether or not (or rather how soon) I'm going to have to replace the rims.

Given that I like wider rims I might just get a set of the gen 2 rims, tape them together, and swap the spokes over one at a time (the ERD only differs by 1 mm, which shouldn't be an issue). Hopefully these grooves in the rim are wear indicators and I've got a fair bit of time yet (as the new rims aren't exactly cheap). I'll have to get them on the bike and on the trainer and see how they spin.

It really doesn't matter if they're wear indicators or not, you can probably use them as such.

The bottom of the groove most likely determines the minimum rim width. If you consider the idea that a chain is only as strong as the weakest link, the added braking surface material doesn't add any strength, so wearing it down to the groove depth can't weaken the rim. Of course there's every possibility that you can wear the rim beyond the bottom of the groove, but at least you know that wearing it to the bottom won't hurt.

BTW- all the above depends on the groove not being where there's added material on the inside, but IME I've never seen one that was.

If you clean the rims to examine the shape of the bottom of the grooves, that would give you some hints as to whether they were machined there by design. If you take accurate positional measurements of the grooves, relative to a reference (the OD edge of the rim, say) and relative to each other, you could further infer whether or not they were put there by design.

Having no idea about the rims, I would not wager a guess -- but if, upon inspection and measurement, the grooves do appear to be purposefully machined into the rim (i.e. matching shape and position), I think it would be safe to say that they are designed as wear indicators.

I think that 4 identical grooves (both sides of 2 rims) is enough to infer that they are there by design, without needing to know anything else.

@FBinNY: Yes. That is my point, exactly.

If you re-read the OP, there is some considerable inaccuracy in the reported measurements (i.e. 1/4"~1/2")
and some doubt cast as to the origin of the grooves: Insofar as they are identical, they can be assumed to be there by design, and thus wear indicators. Or at least, functionally equivalent to indicators, as you pointed out in your previous post. I was pointing out a reasonable way the OP could determine a likely answer to their question.

I've never seen an SL23 with concentric grooves. To my knowledge, the only style wear indicator they've used (on 1st and 2nd gen rims) is a small hole milled down to minimum brake track depth. I would suggest OP give Pacenti tech support a call (423-531-6136) to get their take on whether this is a problem.

Yes. My SL23 have wear limit divots in the brake track 90 degrees from the valve stem hole. Some years ago wear limit indicators became mandatory in the EU, IIRC.

Wow, I never thought of it that way, but you're right. I've seen pictures now that even the first generation ones had a circle drilled in as indicator, so that's probably not what these are. I wonder if the previous owner somehow managed to get something sharp on the edges of his brake pads that caused them. It's odd that they're all the same uniform spacing, positioning and depth (or at least close enough that I can't tell the difference). Since they are all uniform and I'm riding on the trainer for now (actually on rollers with a fork stand because I got the rollers and then never got the confidence to ride them like they're supposed to be ridden), I'm not using the brakes much. When I manage to go outside, I'll re-evaluate (or use a different wheelset). I'll check for the machined divot the next time I see the wheels (I left them at my office over the weekend), to see if that's still there and can go by that instead.

As I said in the OP, I bought these for the hubs (they're powertap hubs that were a good price and I've been wanting to try Zwift to make all the early morning riding I do staring at a wall in my basement a little less boring), and considered the fact they were laced to rims a bonus as it will get me up and riding faster, so, if I have to buy new rims and relace the wheels before riding outside, it will be a bummer but not the end of the world.

When the DIN or ISO demanded rim wear indicators some years back, the rim makers initial response was to turn in concentric grooves while they were machining the brake track. This was easy to implement and didn't call for an added manufacturing step or new machinery.

Later on, I suspect, either the grooves were acting as stress risers and leading to failures of their own, or makers realized that by cutting in the groove they were weakening a new rim to the strength of a worn rim, which doesn't make a world of sense.

Or, possibly, after initially adapting to the rule, the makers had time to create and implement a batter solution, so the grooves gave way to the dimples.

One of the ironies of the grooved rims is that they actually get better with wear, which mitigates the stress riser effect of the grooves until such time as it eliminates it entirely.

Hmmm, so this could be a set of rims that came even before those early ones I saw that had the dimples. That's good to know. I guess I'll ride them and see what happens.