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Hyperpro Suspension Update

M

mcgyver74

Member
Member
Spent some time yesterday trying to dial in my suspension...  So I headed up to probably the only motorcycle shop I trust (European Cycle Services in Middletown NY)  since they are suspension masters (They do a lot of race work)

First step was to measure the sag,  we set the suspension where Hyperpro recommended a good starting point would be and measured..

Front sag: 50mm  :-\

Rear Sag: 47MM  :-[

So now to try to dial it in,    We ended up bottoming out the front preload adjusters and were only able to get it down to 45mm sag, and the rear we were able to get to 34,  but we wound up backing off the rear because it was raising the back end of the bike up to hard and the guys told me it would make it harder to steer like that.

We then went over the damping settings,  the front compressions dampers we wound up backing off entirely since the suspension was way too sluggish (which probably explained some of the uneasy feelings I get in turns on rough pavement) it's much better now, but not great,  without opening the forks and looking at the valving we couldn't get it any closer...(We just didn't have time to)

The rear shock (which I replaced with the hyperpro shock) we were able to get both compression and rebound damping set properly (The shock is a well made unit)


So we concluded that the front springs Hyperpro sent me are inadequate for this bike which is VERY odd given that they sent a 800 - 1400kg progressive spring which SHOULD do well since  the stockers are 1.2kg and Racetech's website recommends a 1.1 for my weight etc on that bike...

AS for the rear, we decided the Rear spring should be increased  since to get the sag correct we close to bottomed out the adjuster,  we can get it correct as is, but if I wanted to take a passenger etc it wouldn't be enough

We then looked at our options for the front end, they (ECS) are big fans of RaceTech for suspension parts, and initially they were going to recommend the GoldValve kits, I then asked them about the Traxxion AK20 kit and the owner spent some time reviewing it and then told me for the C-14 the Traxxion was the better choice for 2 reasons..

1) It replaces the stock cartridge completely with much better made parts, and the stock cartridge isn't the greatest, so it's an easy swap.

2)  The AK20 gives you both rebound AND compression damping which are adjustable from the fork caps,  One adjuster becomes compression and one becomes rebound,  he said this is a VERY good idea since once you get things dialed in, if you need that extra bit of "tweak" on one area, you can actually run different weight oil's in left and right forks to achieve this


So I am going to order the Traxxion kit this week,  the rear shock we are going to still use, since it's a decent unit just increase the spring rate
 
Mad River Marc said:
So we concluded that the front springs Hyperpro sent me are inadequate for this bike which is VERY odd given that they sent a 800 - 1400kg progressive spring which SHOULD do well since  the stockers are 1.2kg and Racetech's website recommends a 1.1 for my weight etc on that bike...
Click to expand...

This is not entirely surprising, as the numbers provided by Race Tech are mostly loose guidelines. For a properly dialed-in bike that is ridden aggressively (and one that is quite heavy), it tends to be best to order springs that are a bit stiffer than those recommended by Race Tech's online spring rate calculator.
 
You're gonna love the Traxxion cartridges. Another plus is if you sell the bike, put the stock cartridges back in. Then you can get the Traxxion AK unit re-valved for your new bike (or so I was told by Traxxion).
 
Why not just get the full Ohlins ZX14 forks and be done with it Marc??
smiley_dunno.gif
 
Because he has common sence :)

I was going to up grade the suspension , BUT I'm waiting for Kaw to up grade the Connie,
What I mean is when Kaw puts Cruise control and that 1441cc motor in the Connie I'll do up the suspenison and move all my farcles over to the new bike and put 100,000 + miles on it because I don't know what else in the world I could ever WANT in a bike , (except a Honda Rune , for $hits and Grins, Sunday rides, piss off the Pirates  :D
 
Mad River Marc said:
ZG said:
Why not just get the full Ohlins ZX14 forks and be done with it Marc??
smiley_dunno.gif
Click to expand...

LOL cause while I like the Ohlins forks, sadly those are quite a bit out of my price range :)
Click to expand...

Be creative bro, surely there must be something in the garage/shed/attic not being used that you could sell...  ;)  >:D
 
well, i just had springs and the gold valve kit installed, picked the bike up yesterday. Knew about the cartridges, and the advantages, tried to weigh the cost/reward for me. hope i did ok.
 
I've been real happy with my AK-20 Traxxion set up, and have had no problem getting the proper front sag, which I now have set at around 35mm, and I still have lots of room left on the adjuster. It's also real easy to make adjustment to both compression and rebound damping, since I can reach the knobs while I'm riding.

Max was previously offering a discount to COG members. You might call them and ask if they will still do this. I know that if you "Like" Traxxion Dynamics on FaceBook it gets you a 10% discount.

I also had to do a spring swap on my Ohlins rear shock to get the sag and ride feel where I wanted it to be, but now I'm really happy with it.

One of the characteristics of progressively wound springs is that they have more initial sag, and so they usually need more preload applied to them. Traxxion and Ohlins both use straight rate springs, so they don't have this problem. There are good and bad points to both spring types, but if you get the proper spring rate to begin with, I think a straight rate spring works better overall, but choosing the proper spring rate becomes more critical with a straight rate spring.
 
By the way, another point I'd like to make is that both Traxxion and Ohlins told me they thought the OEM 1.2kg springs in the C14 were too stiff. For my weight (200 with full gear) Traxxion sent me a 1.0 kg spring for the right leg and a 1.1 kg for the left, since I was right inbetween two different spring rates. I believe they nailed it right on the money.

I went through three springs on my Ohlins rear shock before I got it right. The first was a 140 n/mm with 12mm of factory applied preload (too stiff), the second was a 130n/mm with 12 mm of factory preload (too soft), and the third one was a 137n/mm with 10mm of factory preload (Goldilocks said this one was JUST RIGHT).

Also keep in mind that many rear shocks will have adjustable collars on them that will let you adjust the amount of factory preload applied IF you have a spring compressor. This sets the starting amount of preload applied before you even turn your adjustable preload knob. I found that just a change of 2mm in the factory applied preload on a rear shock spring made a HUGE difference in being able to achieve the proper sag numbers I was after, and consequently greatly impacted the ride and handling. You can sometimes do the same thing with fork springs by changing the length of the spacer that goes over the springs, which sets the factory applied preload.

*note

  130 n/mm = 742 lb/in
  137 n/mm = 782 lb/in
  140 n/mm = 799 lb/in

  1.2 kg/mm = 67 lb/in
  1.1 kg/mm = 61.6 lb/in
  1.0 kb/mm = 55.9 lb/in
http://www.hraefn.net/projects/spring_rates.php
 
And just one more thought...

If you find yourself between two different rear shock spring rates, I found through trial and error, that the best solution is to use the stiffer of the two springs, but have them reduce the amount of factory applied preload a bit. This will become even more important when you load the bike up for a trip.
 
Thanks Fred, I am hoping to have the $ in a week or so to order the Traxxion kit and I am going to see if I can get a slightly stiffer spring for the shock (or look at the factory preload :) ) 

When I get it I will try to remember to document the install of the AK20 for the forum :)
 
Now you see why I made a chart for my pre-load settings and taped it inside my saddlebag. It's a lot of work getting a suspension system set up correctly, and once you have it, you'll need to make sure to record the proper settings so you don't have to go through it again.

I have a photo gallery on line showing the Traxxion AK-20 installation here:  http://www.pbase.com/fredharmon/traxxionak20
 
Keep in mind that the front and rear sag has a huge effect on the way the bike handles and responds.

If you increase or decrease both the front and rear sag together, you effectively raise and lower the bike. This impacts COG (center of gravity) as well as ground clearance.

If you raise or lower just one end of the bike, it causes weight to transfer toward the end you lowered, or away from the end you raised. So if you decrease rear end sag, you just caused weight to transfer to the front end. And the end you removed weight from will then start to feel stiffer as a result, since there is not as much weight on the spring. The dynamics of the rear shock linkage also comes into play as ride height changes, because the rear shock link action is not totally linear through it's range of movement.

Also, raising or lowering just one end impacts the front end steering geometry (rake and trail) and this will impact turn in characteristics. Lowering the front, or raising the rear, will make the bike turn in a bit faster. Raising the front will slow the steering down, and if raised too much, can make the bike feel tipsy at slow speeds.

So getting the front and rear sag set properly is critical to having a good suspension set up, and this is why you want to get the sag correct FIRST before you mess with the damping settings.
 
Thanks Fred,
I just bit the bullet and ordered the AK20 kit and new fork seals.  Hope to install them this Saturday :)
 
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