Out of curiosity I decided to try to get an understanding on the average lap time difference between top drivers in the 100cc (KA/VLR) class versus the 125 TAG classes (which seems to mean solely X30 these days as USPKS and SKUSA run X30, ROK doesn’t seem to run the ROK GP class anymore, and as far as I know Rotax doesn’t run a 100cc class).
I believe my findings themselves might actually explain part of the reason for the decline of the one class in favor of the other, as well as why this decline has appeared to be regionally sensitive, too:
To start out I looked up 2024 USPKS and SKUSA results for both classes and started comparing. Fairly quickly, something that became both interesting, and an obstacle, was the abundance of data points for east coast and midwest tracks for the X30 class versus the lack of data available for the class out west. That is to say that the class barely exists on the west coast, to the extent that the sample size isn’t large enough to fully count on observations about lap time differences. At the same time, I also noted that the AVERAGE speed of many west coast tracks for the two classes is in the 40’s mph range, which is substantially below that on the east coast or midwest track and that at those tight west coast tracks the delta between lap times of the 100cc classes and X30 was almost zero.
Contrast that to the delta which seemed to consistently exist on tracks with a mid-50’s mph AVERAGE speed, of the 2 second a lap range.
What could be concluded/asserted (perhaps wrongly):
a) The tighter/slower a track is the closer the delta between 100CC and 125TAG lap times.
b) The 125 TAG classes have, over time, stayed more popular in areas with faster-flowing tracks, and less popular in areas with tighter tracks (understandable - why bother ponying up for a more expensive class if it’s not really going to be faster).
(if you stuck around this long, thanks for reading and for furthering feedback/information)
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You may have something in that tighter, more confined tracks don’t let the 125’s really stretch their legs, and thus make them less appealing, but I wouldn’t exactly say that there are “healthy” x30 grids in the east either. It would be interesting to dig into the club level data and look at turnout over the last 2 years, but I’d venture to say that the cost of 125cc water cooled racing has priced pretty much everyone at the club level out in favor of the KA100/VLR, regardless of track type.
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This subject fascinates me so I’ll keep posting new stuff I find about it. The latest evidence I’ve found that supports the idea that it takes a fast track to expose any substantial advantage between a 125 TAG and a KA/VLR is video of a ‘fast lap’ that the latest winner of the local KA class posted of himself driving a X30, which was taken only 9 weeks ago (so it’s recent, aka a good comparison). Crazily, his KA race laps, let alone his KA qualifying times actually dipped under the time he turned on his X30 ‘quick lap’.
For me personally, discovering this feels like a relief, because driving a 125 TAG kart at this track myself, I began to feel like I was taking crazy pills when looking at the fast KA lap times compared to what I’m turning (e.g., essentially the same).
If this type of dynamic doesn’t affect you, it probably seems fairly unimportant/uninteresting, but nonetheless I bet it’s done a couple things pretty well:
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Deservedly built the adoption and reputation of the KA/VLR at tight tracks. They deserve adoption and a good reputation elsewhere too, but at the tighter tracks a 100CC TAG appears to truly be a ‘no-brainer’ unless you just happen to like greater expense and more complexity for no advantage at all, or having people who spent less money for less hassle keep up or pass you.
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Disoriented those who are driving the 125 TAG karts and do not understanding the complexities of the situation (e.g., “my kart is a ton more money than these other ones, and I’m/it’s slower - WTH!”).
Let’s just say I don’t think it’s necessarily coincidental anymore that the big group of TAG grandmasters that used to exist at the track has disappeared since the KA started blowing up around here.
An update
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To beat a dead horse - it’s definitely a thing that tighter tracks will negate much of the advantage of a 125 tag over a 100cc tag (KA/VLR). (in addition to the already mentioned ‘local hot shoe’ video of X30 times that are the same as the fast KA’s around here, I’ve additionally seen video of a top 10 national driver with a Rok GP, on the same track, turning the same times)
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The laps from those drivers were under practice conditions and I’m going to give the benefit of the doubt that if it were race circumstances they could figure out how to eek out some more speed that would probably push the 125cc tags to ever so slightly better the times of the KA/VLR - namely by running it the same way folks run the KA’s around here (spinning them as high as they can go 17k)
In what I hope will be an actual positive thing to come out of this, I’ve realized that under these circumstance my rev-limited Rok GP is seriously handicapped, and so will attempt to convert it to a SuperRok, which can then spin to 17k (vs 15k).