RaceBoi: Tito Duality, Tomiboi Hellhound, 21S4P, 4WD 6395+6385, BN straight cuts, 9x3.5s, D100S (formerly RaceBro)

Also, I tried some new 9x3.5s from Deli. Bought it for 8€ including tax. So like 6.5€ without tax.




Sidewalls felt softer, when they let loose it felt less sudden. That said I am very used to the CST’s handling and have zero issue keeping those at bay when they let loose.

They were throwing rocks everywhere like crazy! Probably due to the fresh mold release. I decided to take them off after a couple of laps because I didn’t want to get a rock in my eyes without glasses. I’ll let my friend wear them in. Definitely better than his 8x3s I think.

Grip was pretty decent on them though! Felt like about 80-85% of what I can grip on the CSTs. For 6.5€ without tax that ain’t bad :crazy_face:

I’ll test them again when my friend wears them in properly. But looking promising so far.

Only one issue. The lip was too tight and they didn’t seat correctly. That said for T-racing, I hit 50 km/h on them and didn’t feel them wobbling. Either I need to take another crack at reseating them or just ignore the problem and hope they don’t start wobbling too early. They are super heavy which in my experience means that you cannot usually feel wobbles on them until very high speeds.

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Long overdue Montrevel picture dump:















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Last T-race session before going to Prague and Pardubice

New PB 13.81

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And now some exciting stuff :grin:

I made the trip to the race in Pardubice. Before race day we did a practice session at Kartplanet with @davidpilny and on esk8s I am right now 3rd in the rankings. Only David and @TZDKB ahead of me.

At the beginning of the session I kept getting wobbles above 45 km/h while braking on a bumpy section in the back straight. Welp, running the trucks at more articulation than intended and a lot of preload has caused this:


The flat washer became a cone washer hahaha. And so much so that I basically lost all preload on the bushing.
I quickly took some extra flat washers, added them between the bent washer and the bushing, and now the board is dead stable. Certainly stable enough for setting my PB for Kartplanet!

Actually during the last two T-race sessions I felt something was a bit wobbly when braking hard from 50. Thought it’s just me not being used to 4wd braking. Damn. I was riding like this 65 km/h or 40 mph on roads and didn’t even notice that something was off, because unless I am braking hard it’s just stable. Even without any preload it turns out! And when I was feeling the wobbles it wasn’t violent wobbles. It was tameable with for sure.

However, now that the truck is operating like it should, and after I went up in truck angle, now running 35/12.5d, I feel like the trucks are setup too tight for my liking. So I need to get back to my stack of bushings and play around a little bit.

My first change will be changing one of the front bushings to 93A, and running less preload on the rear. Will see how that feels

Then a small night ride

Then came raceday at Pardubice.

I was putting good pressure on David in the beginning, after 3 heats we reversed direction and I had a small crash, so took it a bit easier afterwards.

The 9x3.5s were really good on this track. Finally the first time where I saw them forming the stress lines from the side loads!

And about 1.5G peak measured!!!

Also I feel like I want more power at high speeds when the limit becomes battery current. After like 3.95V steady state the voltage sag starts feeling like it takes away power. By 3.8V steady state the board feels significantly weaker.

But it’s still very respectable acceleration of course.
Also want more battery current for braking… But will play with throttle curve first. Currently running 180A for that in total with 580A motor amps for braking…

I am at the point where I would benefit from P45B for sure.

Also David’s V5 on the mamba XLX was less powerful for sure.

And second place podium pics!

And tomorrow there’s a short Kartplanet session again with David before I drive back to Denmark. @TZDKB I’ll try hard to get a better time than yours :wink:

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Congrats on the podium, your build is very impressive :rocket: :skateboard:

I get that a lot. Two longboard bushings aren’t enough for wide esk8 trucks.

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Nuts!

Been reading a book on how professional racecar DAQ systems are set up and analyzed. There was an interesting section on accelerometer g measurement;

TLDR; on race cars, the “real” magnitude of corner g’s isn’t the max number from the accelerometer, the raw acceleration needs to be filtered.

The book was written in the context of ICE cars, so it’s possible it doesn’t apply here…. I’m curious if you’d be willing to indulge me😁

Do you have a line plot of the acceleration over time? Wondering how much noise is in your data.

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The only graph race box shows for acceleration is very smoothed, similar to the middle line.

One of the tracks that I ride on has one spot with a manhole cover in a slight corner and that spot is always where my peak Gs is shown so it definitely can’t filter stuff like that out but it’s somewhat smooth. It would always show around 1.7Gs or so so definitely not in the realm of possibility for my riding skill

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Interesting! I checked the smooth line and that peaked at 1.07G

About comparable to the smoothed line of what David measured on the BRPs on the same track. He has standard width, 45A rear 50A front.

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Today I got a new PB on Kartplanet, 51.99

That makes me the second quickest on an esk8 on that track!

Also had a run where I did 69.9 km/h in the straight, which is my new record for top speed.

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Got some photos from Kartplanet!

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@tuckjohn @ARCTIC

Coming back to this after analyzing the data further.

Actually I just pulled the raw unfiltered data from some carving and there you can see the noise is basically very low, looks exactly how I expect it to look. Maybe the “raw” data already has some sort of filter implemented on the hardware level? Or it’s just really accurate and not noise. Either could be the case.

Also you can see that the low pass filter racechrono puts over it is totally bullshit for esk8 use, it is just way too strong.

And I hit about 1.64G lateral along with 0.39G longitudinal at one point while carving, meaning about 1.69G combined after doing the Pythagoras (raw data but we accessed there’s very little noise)

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Very interesting. Can you please explain when or what generates each of the the light blue data point dots?

As far as each quadrant of the friction circle, it appears to me that you are generating braking G’s slightly more in left hand turns than in right. Is this due to the fact that the track is run counterclockwise?
Are you capable of generating the same amount of G force equally on your heels as you can on your toes?

Where as G forces of acceleration tend to be higher overall and in a more of a straight line?

The racebox measures the acceleration on every axis periodically, each blue dot is one measurement.

The track can play a part in it sometimes, but with this many different corners and from the data of many laps, this is probably due to me not being as good in one of the directions.

The purple G force line can be ignored because it basically doesn’t know what’s going on, it’s filtered so heavily that it needs more time to change significantly in value than my carving periods take. This is probably because it was tuned for motorcycles and cars, which I guess don’t change direction so suddenly.

This video is only about a part where I am carving on the straight.
On the graph in the bottom the yellow is the lateral acceleration and the green is the longitudinal acceleration. Pink is speed and purple is supposed to be the pythagoran sum of yellow and green, passed through a low pass filter.

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Fascinating, very cool. Thanks for sharing!

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And today I just did a 13.44 toeside lap on T-race

Despite the fact that the battery was at 3.85 steady state where I usually really start feeling the voltage sag eating into the power.

And despite that the temperatures were quite low so I couldn’t warm up my tires basically at all therefore they didn’t grip super well.

Two interesting facts to note. Firstly I barely spent any time within the 0.5G circle, meaning I was smooth with applying trail braking, coming onto the throttle out of the corner, and doing all that while keeping the acceleration high for the whole time.

Secondly this lap is 114m which is my shortest lap in recent times. So maybe Jeff’s theory that my laps are too short doesn’t hold up at the power I put down currently.

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I’m pretty sure we’re supposed to open our eyes whilst riding.

Nevertheless, congrats on getting 2nd. I’ll be sure to attempt to take that back in November though that might be too cold haha. Unfortunately won’t be contesting your T-Race times anytime soon cause the tarmac here is shit, can’t beat or even get close to my own times I set in Prague.

On the G-Forces thing though I noticed spikes in Montreval due to the cracks and surface imperfections though in Karplanet there are quite minimal spikes. I imagine that your mahoosive tyres would help minimise this too.

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With how photogenic I am of course the photographers always catch me when I blink :sweat_smile:

I will try to set some more records in November as well don’t worry :stuck_out_tongue_winking_eye: Will be a fun fight!

Hope you can find another T-race spot maybe in the future :grin:

Hmm possible. I didn’t analyze the montrevel data closely. Kartplanet is nice and smooth and I didn’t really see any spikes in the data here.

Regarding just how massive the tires are compared to the linnpowers :sweat_smile:

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that’s just comical

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Also probably the reason why the first set is still going strong after countless sessions during the last half an year of constant racing :eyes:

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Got a 13.97 heelside today, which bumps me up to 9th place in the overall standings for T-race!

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