ultimate motorbikes

[WiK1d]

Went out to Redstar Raceway again yesterday. Perfect perfect day. It couldn't have gone any better.

The trip there was fantastic, Frits and I left Pretoria at about 8.30 and got at the track exactly an hour later, not bad for the little Honda! Unloaded all the stuff, got the bike on the stands and put the warmers on (Thanks Cassie, they are super cool, or should I say, hot ). Paid and then got a bite to eat. Suited up, booted up and went out for the first session.

Not a bad session at all, especially as a start to the day. Bike was behaving once again, but I wasn't. Did a sprocket change over the weekend (Thanks Franco for helping me out!) and the bike sings through the gears now. That completely stuffed up how I was used to riding the bike. I had to figure out what gear to be where, when I usually only went one gear down or none at all I was going two down, it was all confusing and I outbraked myself quite a few times. Even through all of that I still managed some decent laptimes: 2.22, 2.18, 2.19, 2.16, 2.17, 2.16, 2.18. Very happy, but the rear tyre was not looking as nice as the previous visit, but I couldn't figure it out, pics later.

Here is session one:





Since there were only 2 classes and very few guys on track there wasn't a lot of time for sitting around between sessions. The 2nd one went better than the first, but I was still struggling to get a new rhythm. Even through all of that, I did a new personal best. Here are the laptimes: 2.17, 2.16, 2.16, 2.14, 2.14, 2.19. So that's pretty consistent and I was really pleased with that.

Here is session two:



I quickly showed Frits how to use my camera after session one and let him go on his merry way, here's a shot from pit-wall



The third session came after lunch so I had some time to sit around, gather thoughts and energise. Decided that it was make or break time now and through the whole session I only made one mistake where I ran wide, can't even remember where it happened. It was another very consistent session which resulted in a new personal best, again! The laptimes were: 2.17, 2.16, 2.15, 2.16, 2.16, 2.15, 2.13, 2.15. I am really really pleased with that result!



This time Frits went into the track to take some pics, here's one of my favourites



I was getting quite tired by this point, but I still pushed on. Session 4 was another decent one with laptimes looking like this: 2.22, 2.17, 2.13, 2.15, 2.14, 2.15. Managed to match my personal best again which was good, but I felt faster, so I'm a bit disappointed, but still quite happy!





For my last session of the day I went out with a ZX10 following, I let him through with the intention of trying to see where I can make up some time. Turns out it was Stephan! (as I found out after the session) Nice meeting you! He had a little accident at Kyalami so he was a bit nervous and I went past after about two laps. I was meant to take it rather calmly for the last session, but excitement overcame me and I went at it hard. The rear was starting move and slide quite a bit now, so I decided to pit early and just call it a successful day. Which it indeed was. No video of the fifth session as creativity for mounting failed me. That also means no laptimes, but I think it was around 2.15's, didn't push that hard in the session.



Overall I'm very happy with my progress. I'm a bit disappointed that I only dropped two seconds, I have to go figure out if I maybe lost some speed on the straight as a result of the sprocketing. Could also be due to the tyres, but definitely not the weather, it was a fantastic day!

I know there are some spots that I can still improve, but I braked later in some turns, was harder on the gas in others and even finally started trail braking (thanks for the pep-talk Cassie!). So far it was all positive, now comes the only negative part.



Yup, I am SUPER unfit and my body is absolutely hating me today. I might have to join you at the gym Cassie

Here's the rear tyre after the final session of the day. It's done on the right hand side now, but the left doesn't look as bad, which makes me think Craig is right when he says throttle. The righthanders and the ones leading on to the straights and the hard acceleration, paired with a stiff shock might be the cause.



That's it from my side. Just gotta once again thank Franco for the help over the weekend, Cassie for the warmers, stands, trailer and confidence talk and lastly, Frits for taking these awesome photos on his debut as a photographer. Great job dude!

[DarkStar]

I wonder, these track-day places, would you be able to enter in with an old (say, 1981 KZ550) bike?

Just curious

[SykomantiS]

Awesome wik. Looks like you had fun.

Mind telling what exactly you did with the sprocketing?

[WiK1d]

I wonder, these track-day places, would you be able to enter in with an old (say, 1981 KZ550) bike?

Just curious

For sure, a few weekends ago there were a bunch of tards on cruisers scraping exhaust pipes around the track. As long as your tyres are decent and it's not leaking (well, it's a Kawasaki, so you're screwed ) there should me no issue.

Awesome wik. Looks like you had fun.

Mind telling what exactly you did with the sprocketing?

Thanks man, yeah, it was a great day out. I went down two teeth on the front, which is about 6 teeth up on the rear, so it pulls like a motha'ucka now!

[SykomantiS]

That's vicious man.
(I had it that -2 front == +4 rear, but I guess it depends on the overall tranny and is different for each model)
Either way, should be good fun. Do run into the limiter on the straights?

[WiK1d]

That's vicious man.
(I had it that -2 front == +4 rear, but I guess it depends on the overall tranny and is different for each model)
Either way, should be good fun. Do run into the limiter on the straights?

Yeah it's a lot of fun. Lifts the front in first on the gas, 1st to 2nd lifts the front, 2nd to 3rd lifts the front. Very exciting to ride now! It's actually almost perfect for Redstar now. I'm getting up to about 13k RPM in 6th down the back straight now where usually I would have just made it into 5th.

[SykomantiS]

Sounds awesome

Well if you're not limiting then I doubt that you're slower in the straights. Perhaps you just need to get used to the new setup.

[WiK1d]

Sounds awesome

Well if you're not limiting then I doubt that you're slower in the straights. Perhaps you just need to get used to the new setup.

Yeah, I made this little comparison video to see what's what:



Seems I'm not really losing speed on the straight, made up all my time into turns 8 and 9

[WiK1d]

July 6th Report.

In a word. Bad.

Got a new rear from Grant (thanks man, hope you're enjoying the drink) which was of the 190 flavour, instead 180 that's usually on the bike. Boy did that stuff the handling up. That added to the incredibly cold conditions we had made for a very un-confident rider.

First half of the day I spent riding around with my mate showing him how to improve. Didn't really notice the handling issues then. He pulled in one session and I decided I'm gonna go for it. As soon as I completed the back straight and was leaned over on the left I could feel something was up and mid-corner the bike just started drifting wide. This continued for the rest of the session and I found I was pushing harder in other parts to compensate for that.



(Something got messed up in the processing so the video looks bad, I apologise)



Session after that I went out on my own after I changed some settings on the shock. Oh dear me. Wrong direction. Took it calmly first lap, 2nd lap went at it, followed a Priller into turn 3 (after the back straight) dropped in at my usual speed then suddenly the bike wouldn't hold it's line and I picked the bike up and ran probably 50-70m off track. Thank goodness there's a lot of space to go. Changed the settings back to stock and they were better, but I still wasn't happy. I've got to go back to 180's, I can't go on like this, I was really really uncomfortable yesterday even though I still ran 2.14/2.15's.





(Wait, this isn't where I parked my car?)

At least I got this relatively cool video:



It's only 18s, so worth watching in HD!

But now, the more I'm watching my videos the more I think it's because I was actually faster. Ugh, busy uploading another comparison video. Maybe if I can just sort the suspension issues it will be okay. Only one way to find out I guess.

To be continued...

[SykomantiS]

Well, if you were hitting 2.14's like last time then I dunno hey. (your best you said was 2.13?) Sounds pretty much spot on, all things considered.

In what way do feel did the 190 stuff up the handling? Should make the bike a bit slower on turn-in, right, but then you should also have more grip. (How much more I wouldn't know- but that's the theory anyway).

Also, out of interest, what brand/type was the 180, and what is the 190?

[WiK1d]

Well, if you were hitting 2.14's like last time then I dunno hey. (your best you said was 2.13?) Sounds pretty much spot on, all things considered.

In what way do feel did the 190 stuff up the handling? Should make the bike a bit slower on turn-in, right, but then you should also have more grip. (How much more I wouldn't know- but that's the theory anyway).

Also, out of interest, what brand/type was the 180, and what is the 190?

That's why I'm so frikken confused. I'm thinking that I was actually pushing harder which might have been the reason for me running all over the show, but the tyre is definitely also to blame as the bike felt completely different. It would enter the turn fine, but mid-corner it would start drifting wide and it would push the bike wide on corner exit. I need to fiddle with the shock a bit and see what's what.

Thing is, the Triumph is VERY finicky when it comes to geometry and I've heard of others complaining about 190's (plus, it's a 5.5" rim, not a 6" rim). I'm sure I can dial it out, but it's not the ideal solution, I'd prefer to go back to 180's.

It's the exact same tyre. Metzeler Racetech K1's.

[SykomantiS]

I'll see if I can a bit of info had the other day on suspension. I was reading up on it. Specific changes get specific results.

Err, the 5.5" should make the 190 behave more like a 6" 180 (but then again, the 180 on the 5.5" will again be different, so it's a moot point)

And yeah, pushing harder might have something to do with it.

[SykomantiS]

This wasn't what I was looking for, but it does have a troubleshooting guide. Check it out. Might be a good place to start you in the right direction Click

[WiK1d]

Err, the 5.5" should make the 190 behave more like a 6" 180 (but then again, the 180 on the 5.5" will again be different, so it's a moot point)

And yeah, pushing harder might have something to do with it.

Thing is, the rim pinches the 190 which theoretically gives you a steeper profile, but that isn't always a good thing.

This wasn't what I was looking for, but it does have a troubleshooting guide. Check it out. Might be a good place to start you in the right direction Click

Thanks, I'll give it a read. I've also got some documentation that I read and tried adjustments and that made the bike much worse, so I went back to what it was for my last session.

I've gotta do some reading and then test it out at the next trackday.

[WiK1d]

I've been watching some Dave Moss videos again. He said the Trumpet can actually take 190's without an issue. What happens though is that it indeed stuffs the geometry up, so I just need to sort that and the bike should behave as she did before. I'll be firing off an email to the man to find out more. He said it's geometry, not valving that's the issue (so I can't just fiddle with the compression and rebound and expect it to get better)

Anyhow, here are two more comparison videos.





I know when I compared the 2.14 lap of the 6th to a 2.15 lap of the 29th I was by half track distance about 2 seconds ahead! Then I got stuck behind the Priller and lost all that time.

[Hman]

You'll most likely have to lower the rear a little bit.

[WiK1d]

You'll most likely have to lower the rear a little bit.

That's what I thought as well, but a lot of suspension tuning is counter intuitive. Mr. Moss said by going to a 190 you're removing rear ride height, so you need to raise the rear ride height. Which makes sense from a handling point of view. If the rear was taller the front would be sharper and the bike would steer easier, which was definitely not the case on Wednesday.

[Hman]

Depends on the profile and the effect on the diameter. If the 190 se profile is such that the diameter increase you need to lower the rear and vice versa. The fact that you put the tire on a 8.5 rim might increase the diameter of the tire slightly as well.

But then again as you state the bike's steering is lazier now which would indicate rear ride height being lowered with the 190.

[WiK1d]

Depends on the profile and the effect on the diameter. If the 190 se profile is such that the diameter increase you need to lower the rear and vice versa. The fact that you put the tire on a 8.5 rim might increase the diameter of the tire slightly as well.

But then again as you state the bike's steering is lazier now which would indicate rear ride height being lowered with the 190.

It's the exact same tyre, so obviously the diameter increased, but that decreases your swingarm angle, which means you need to put in rear ride height to restore the angle to between 10 and 12 degrees.

[Hman]

This is confusing, either way we can agree that a height adjustment is in order.

[WiK1d]

This is confusing, either way we can agree that a height adjustment is in order.

Hahaha yeah I'm also struggling to wrap my head around it, but I think I've got it figured out. I'll draw a picture to demonstrate.

Height adjustment it is indeed, just need to figure out how. Possibly spring pre-load, as I don't think the stock shock is height adjustable.

[WiK1d]

Okay, so I drew this up to try wrap my head around with what's happening with the rear-end



I tried to use as accurate measurements as I could quickly find, but it's all relative, that's the important part.

Changing to the 190 alters the swingarm angle by a moerse lot, didn't realise that. That would definitely explain my issues. Your swingarm angle should be between 10 and 12 degrees. So I need to force the rear shock to raise the rear end to restore the swingarm angle.

Makes sense, I think?

Opinions please.

[SykomantiS]

My head hurts (>_<)

Here's why:
The weight of the bike doesn't change, so we can assume the preload (errr, that is to say, the amount the spring is compressed by weight) on the spring due to weight will be the same, regardless of tire, yes?
No, I agree with the second part of the pic, where the wheel will be under ground level. What I don't get, is why the angle changes when raised to ground level.

Ok wait, maybe I do understand that, but I disagree with your upper measurement of 531.6 changing to 511.3. I get why the lower measurement changes (increased radius of the tire) but the seat height and therefore the seat-body-swingarm angle of the bike does not depend on the tire radius.

Does that even make sense?

Come to think of it, fitting a 190/55 to the bike should stand it on its nose.


That's what my brain tells me. Either that or it's seriously time to go home and have a beer

[Hman]

I don't think the angle of the swing arm is very important, adjust your rear height to get your rake angle back to what it was should be more important, to do that with the 190 on you should lower the rear.

Raising the rear will decrease your rake angle making the front end more nervous. It will also move your weight distribution forward increasing grip in the front but lowering it in the rear.

[WiK1d]

I don't think the angle of the swing arm is very important, adjust your rear height to get your rake angle back to what it was should be more important, to do that with the 190 on you should lower the rear.

Raising the rear will decrease your rake angle making the front end more nervous. It will also move your weight distribution forward increasing grip in the front but lowering it in the rear.

That's where you're wrong. Swing arm angle is a crucial component of your rear suspension. Not enough will cause your bike to squat and therefore force the bike wide. Why do you think AMA/SBK teams have dedicated devices to measure swingarm angle?

I've send Dave Moss an email and will wait for his response.