[dogged]

I'm currently in the tweaking phase of the suspension for my race bike. I am 140 lbs, so I started by dropping one fork spring rate to a 0.9. Just FYI, we discovered the air gap at the top was only 80 mm from the factory! This was on a 2017. We lowered it to 120 mm as a starting point and I'm now using almost all the travel (spec is 150 mm).


Anyway, my next step is dropping the rear spring rate down a notch to a 95. While the shock is off, I think I want to try and raise the bike by putting a spacer under the shock mount. I have a friend that used to support an AMA race team and he told me that this bike really wants 10mm up in the back and raise the front all the way up to the top of the forks and the handling will take a noticeable leap better in stability with no loss of turn-in.


What sort of experience have any of you had with changing these parameters and what magnitude did you end up with? Thanks for your feedback!

 

[MGFChapin]

Attack triples or stock?

 

[dogged]

Attack triples or stock?

Sorry, it's a Superstock build at the moment. Probably putting a cam and ECU in next season for a Superbike.

 

[MGFChapin]

That's sort of the opposite direction you want to go with the bike. It already suffers from too little trail, so putting the forks flush with the top triple is a great start. Raising the rear will make the problem worse. If/when you get aftermarket triples, that's a good time to experiment with raising the rear.

 

[dogged]

That's sort of the opposite direction you want to go with the bike. It already suffers from too little trail, so putting the forks flush with the top triple is a great start. Raising the rear will make the problem worse. If/when you get aftermarket triples, that's a good time to experiment with raising the rear.

I felt the same way, but he promised me that just raising the entire bike (both front and back about the same amount) made a huge difference in how it handles (in a good way). That's really the reason I was soliciting some feedback from those who may have tried it before. I don't really have stability problems with it now in my opinion.

Theoretically, if your C.G. is higher, it should turn in faster and if you can offset the rear height raise with a corresponding front, then it should be a better machine at the same level of stability. At least in theory!

 

[MGFChapin]

You'd need to raise the front by an equal 10mm to achieve the balance you're talking about and there isn't enough fork to do that. You'd need fork cap extenders, but the true fix is aftermaket clamps.

I didn't think I had stability issues with stock clamps either, even after riding another bike with Attack triples. Then the front let go on a teammate pretty unexpectedly during an endurance race and I'm planning on Attack triples over the winter.

 

[dogged]

You'd need to raise the front by an equal 10mm to achieve the balance you're talking about and there isn't enough fork to do that. You'd need fork cap extenders, but the true fix is aftermaket clamps.

I didn't think I had stability issues with stock clamps either, even after riding another bike with Attack triples. Then the front let go on a teammate pretty unexpectedly during an endurance race and I'm planning on Attack triples over the winter.

That's a good observation. I was planning on maybe splitting the difference at ~5mm just as a starting point. I'm currently 3 rings down in the front, so I probably have about that much to give and keep the geometry stable.

 

[MGFChapin]

That sounds like a more logical approach. 5mm should be noticeable without being too big of a change.

 

[Zaph]

I have a friend that used to support an AMA race team and he told me that this bike really wants 10mm up in the back and raise the front all the way up to the top of the forks and the handling will take a noticeable leap better in stability with no loss of turn-in.

I agree with MGFChapin's initial response, that is the opposite of what you want to do, at least in the rear.

On a stock 13+, with OEM triples at least, the best thing to do is lower the rear by milling down the shock spacer by 5mm and then lowering the forks down so they are level with the top triple clamp. Then your rake goes from a skittish and vague 22.9 to a solid and predictable 24 degrees. You go from your front end washing out unexpectedly to being able to feel the limits as you approach them.

IMHO, the only reason to raise both ends is to allow for more cornering clearance, a problem the Daytona doesn't have.

 

[MacBandit]

Raising both ends equally will mostly only change how it feels not the actual quality of handling. If anything it will slow the turn rate down by moving the center of gravity up. You can get a similar feel by going to a taller tire which will want to fall into turns like a taller bike will.

 

[MGFChapin]

You can get a similar feel by going to a taller tire which will want to fall into turns like a taller bike will.

Another good point. If you're not already running a 180/60, you're doing it wrong.

 

[dogged]

Yep, I run a 60 profile Pirelli SC2.


So, if running a taller tire makes it "fall in" why would not raising the CG via height adjustments have the same effect?


I have not experienced any instability (yet) in my front. Now you have that issue running through my head. So, did you experience no problems then "bam" out the blue a tucked front? That's a little unusual to me (at least running other bikes, and I'm aware each one has its personality). If so, that is really scary to think. Any other contributing factors to that or was it possibly just a tire / surface/ rider/ etc issue? Maybe I'm wrong, but I thought the 13+ did not need aftermarket triple clamps, only the earlier models.




Since the bike is new to me, what sort of feedback should I be looking for to know the front is out of whack? I might go ahead and raise the forks all the way next weekend at practice just for fun and see what it does. I was worried about losing the quick turn-in that makes this bike so nimble if I do though. Thanks for all your advice.

 

[MGFChapin]

I'd done 3 test days before my first race with this new bike and I liked the feedback the front gave me, as I mentioned, even after riding a bike with Attack triples. My endurance teammate had also ridden my bike without complaint. I'm a mid-pack expert racer and he's generally a few seconds faster than me at any track we go to, so he knows what he's doing. About half an hour into his first race session, the front washed out in a slow, second gear right-hander in the transition from off throttle to on throttle, no brakes at all.

Generally with faster corners and I've noticed especially with Pirelli SC's, there's enough gyroscopic effect that if the front starts to let go, the bike still wants to stay upright and you'll experience a little front-end chatter or slide before it dumps you on your ass. This corner was so slow there wasn't much chance to save it. The tires were hot, but the track may have still been a little cold, but he'd never crashed there before on his bike with Attacks.

Aftermarket triples are absolutely recommended for 3rd gens. There just isn't enough trail.

There's nothing wrong with dropping the forks flush right away. That's what most guys I know run. I also run a Pirelli 180/60 and I have 1 line showing on the forks. Except for the oopsie mentioned above, 1 line seems to be a good compromise for me.

 

[dogged]

Great info, thanks. Are you running one line on the aftermarket triples or the stock? I can't change them this season and stay superstock, so I will just raise the front to help keep your scenario from happening. Hate that it happened to your team.

 

[MGFChapin]

One line with stock triples.

 

[RidersDiscount]

Aftermarket triples are absolutely recommended for ALL gens. There just isn't enough trail.

Fixed it for ya :grin2:

 

[bsteve525]

My 2 cents

Here is what I found worked best for my 675R on the track (doing mid 1:30's VIR N) and still works great on the street. The front forks were lengthened internally by 10mm and then put flush with the triples. I took the factory rear shock spacer out (its about 8mm if memory serves). I tried putting washers (from the hardware store, easier than milling) at various heights less than the 8mm and found that they all left the nervous feel in the chassis. I guess it comes down to the feel you like, ie, more stable, more nimble, etc. I like a stable balanced feel. What are you looking for? Did you like the stock feel? I'm not sure if there are ride height differences between the R and standard models.

 

[bsteve525]

Triples

My teammate ran his 675R same as I mentioned above with stock triples and got down to 1:31s on VIR North, so they are capable. He did have one low side though. Then again, he's had a low side on his R6 this year soooooo.........

 

[Skruffy]

Is this true for the street triple as well?

 

[MacBandit]

No. Street Triple has more trail. It's still not as much as some want but it's close enough for most.