Welcome Drum_Transit

If it is a 21" then it isn't likely to be a PING because they came in 20" from 1971, and 18" and 22" were added in 1976. No odd diameters that I've seen, and 21" is not mentioned in the official Zildjian model list.

Rock Rides came in 21" and based on 6 examples with model ink they weigh 2900g (unusually light) to 3900g (unusually heavy 80s one) with a median weight of about 3300g. Rock Rides came out in 1973.

Yes there are also 21" Medium Rides. Medium Rides with model ink have been around at least since the 50s, but I don't have weights of 21" 70s examples with their model ink intact. An 80s one weighs 3056g, which is fairly portly. I may have a few pending records to process will give a bit more Medium Ride specific data. The trouble is that 21" cymbals are relatively uncommon compared to 20" and 22", and then most have lost their ink.

The general weight distribution for 21" cymbals is found on my site:

http://black.net.nz/avedis/avedis-prices.html#21

21" Sweet Rides (a more recent model) weigh in from 2450g to 2550g and have the 6" bell (so I'm told by those who claim to know -- haven't measured one myself). There are plenty of older 21" cymbals (lacking model ink) which also weigh in that range. There are also Light Rides and Crash Rides from the 80s in 21" but they are light as well.

It might be useful to post images of the trademark stamp and the whole cymbal from the top and the bottom. 21" cymbals came with 6" bells (certainly the Rock did) which might help distinguish them from other models which might have a 5" or 5.5" diameter bell. However, I've got a 70s A Zildjian Canada 21" which has a 6" bell and weighs 2660g. Alas it has no model ink left on it. So perhaps it is a Medium or Medium Thin with a 6" bell. I just haven't gotten far enough in data analysis to have all the models sorted out yet in terms of bells.

Thanks for playing guys...

Which diameter bell is "normal" for you two? Do you mean a 5" diameter one? This is where I start to run short of quality data for 21" cymbals. I've got a few ways to measure bells, but it is always a little difficult to define where the bell begins when there is a very gradual bell bow transition. My latest method is a curvature template gauge which allows accurate (1mm) shape and size comparisons. Failing that you are reduced to some of my earlier techniques:

http://black.net.nz/avedis/bells.html#anatomy101

If you've got an 18" - 20" with a 5" bell then you can nest it within the 21" and see of they are the same. I do the nesting both ways (21" on top, 21" underneath) which gives good relative size information.

As far as a 21" cymbal with a 60s stamp which weighs in around 3000g that could be a Medium Ride model. If it has no model ink left it is hard to say for sure. I've got lots more data for 20" than 21" and I see what I need to do is work through all the model ink analysis for 20", 21" and 22" and present them together as a way of informing the relatively sparse 21" weight data.

Also, there isn't anything wrong with finding a 60s trademark stamp on a Rock Ride even thought Rock Rides came out in 1973. The common nickname "60s stamp" is a little oversimplified. On present evidence what we call the "70s" stamp might have a year of first use in the factory of late 1972 or 1973. Notable changes a few years into a new decade rather than on the exact decade boundary is consistent with the 90s (laser stamps 1994), 80s (CO stamp in 1982ish, and hollow ink Zildjian to solid in late 1982) and what we can reconstruct for the 50s/60s boundary. It's just that our expectations are off because we like to oversimplify and use the decade nicknames.

I've recorded one 60s short stamp and one 60s tall stamp on Rock models* which still have model ink on them, compared to 7 "70s" with stamps and 24 "80s" era. So we see production ramping up and/or varying number of production years in each identifiable "production era". The id as "80s" era can be the CO stamp and/or other "80s" ink like the solid ink Zildjian and diameter info. One of the things revealed as sample sizes grow is that it looks like the "70s" stamp outlasted the CO stamp and the "70s" stamp is found on cymbals with late 80s to 1993 ink. But this is all ongoing work and subject to change as more quality data comes to hand.

* note in these counts I've included all diameters as well as Rock Ride, Rock Hats, and Rock Crash. They were all introduced together.

No need. It's a 6" bell all right. Yes Sir I've done a quick comparison of the diameter of the bell in the photo from the top (45mm) and the overall diameter (153mm). Knowing those two plus the real diameter of 21" you can calculate the bell diameter: 6"

It's usually easy enough (and accurate enough) to pick a 6" from a 5" bell even when the exact edge of the bell is hard to spot. A cross check is that the mounting hole is 1/2" and appears as 3.5mm on the photo.

I occasionally have an uncertain outcome when trying to pick a 5" bell vs a 5.5" bell if the edge of the bell is hard to spot. The 5.5" bell is also a little higher than the 5" which helps if you have the cymbals in front of you. But that doesn't work from photos. Jumping2

I'm slowly building up data on which diameter cymbals (and which models) have which bells. There was a common core of 5 different bells at one point (60s?) but since the 80s (or is it more like 90s?) a few more bell dies have been created. Paul Francis has provided some of the specific info on those and in some cases they were actually cloned from much older cymbals.

Unfortunately for the current discussion, what I'm not sure of at the moment is whether that 6" bell die was in use on the 21" Medium Ride in the 60s and 70s.