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petshark

Tracer geometry in relation to suspension upgrade

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I've had my GT set up by a suspension specialist.

I'll share my settings to save anyone with the same weight some money.

I'm 196 lbs / 89 kg with my gear on.

front preload: maximum, 0 lines visibleIMG_0092.thumb.jpg.475c92887a0203de8f5540514bf5f590.jpg
front compression: 1 click out
front rebound: 7 clicks out

front lowered (fork visible above triple clamps): 12 mm

rear preload: 10 clicks out
rear rebound: 5 clicks out

For the next part I hope that I correctly relay the info I got from him:

The geometry of the Tracer is not optimal, it is light on the nose and even though the GT is better with the longer swingarm there's still a lot of room for improvement. This has to do with the angle of the fork or rake.

To fix this the front has to go down and/or the rear has to go up. He went all the way to 12 mm and said this was still not enough to fix the geometry. I already feels like a new bike, the steering feels much more direct.

The next step would be a better rear shock with a longer length to raise the rear 15 mm. He proposed these Wilbers but when I saw that they are actually the same price as Ohlins 537 when you add the hydraulic preload option, I obviously would rather save up for Ohlins. But Ohlins has no option to get the rear higher, I just heard back from them. The specialist agrees that Ohlins is the best and he has great discounts there but to fix this bike he still recommends the Wilbers because the geometry fix has a higher priority. Before someone says that he most likely just has bigger profit margins on Wilbers, I really don't think that is the case here. He actually says he has no experience with Wilbers and I believe that he just wants the best solution to the problem.

So I know there are many here that have suspension upgrades done but I have not found a lot about fixing the geometry, a few posts about dropping the bike on the forks but none about raising the rear. Any thoughts or experiences are welcome.

Edited by petshark

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Penske shocks are very good and have height adjustment.  Check with the folks at Traxxion Dynamics.

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I went for the Penske raised by about 15mm also in the rear. Traction Dynamics AK20 in the front. Major difference! Height is adjustable on the shock but no remote preload available. Very easy to adjust it by hand though. Have your guy check out the Penske and give you his thoughts.

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I'm the same weight as OP, and the front end adjustments made seem awfully extreme to me.

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2 hours ago, petshark said:

I've had my GT set up by a suspension specialist.

I'll share my settings to save anyone with the same weight some money.

I'm 196 lbs / 89 kg with my gear on.

front preload: maximum, 0 lines visibleIMG_0092.thumb.jpg.475c92887a0203de8f5540514bf5f590.jpg
front compression: 1 click out
front rebound: 7 clicks out

front lowered (fork visible above triple clamps): 12 mm

rear preload: 10 clicks out
rear rebound: 5 clicks out

For the next part I hope that I correctly relay the info I got from him:

The geometry of the Tracer is not optimal, it is light on the nose and even though the GT is better with the longer swingarm there's still a lot of room for improvement. This has to do with the angle of the fork or rake.

To fix this the front has to go down and/or the rear has to go up. He went all the way to 12 mm and said this was still not enough to fix the geometry. I already feels like a new bike, the steering feels much more direct.

The next step would be a better rear shock with a longer length to raise the rear 15 mm. He proposed these Wilbers but when I saw that they are actually the same price as Ohlins 537 when you add the hydraulic preload option, I obviously would rather save up for Ohlins. But Ohlins has no option to get the rear higher, I just heard back from them. The specialist agrees that Ohlins is the best and he has great discounts there but to fix this bike he still recommends the Wilbers because the geometry fix has a higher priority. Before someone says that he most likely just has bigger profit margins on Wilbers, I really don't think that is the case here. He actually says he has no experience with Wilbers and I believe that he just wants the best solution to the problem.

So I know there are many here that have suspension upgrades done but I have not found a lot about fixing the geometry, a few posts about dropping the bike on the forks but none about raising the rear. Any thoughts or experiences are welcome.

I agree with assessment on the Wilbers vs Ohlins ONLY because of the ride height adjustment.  Ohlins makes a fantastic shock but I wish they offered that additional adjustment.

I have the Penske 8983 from Traxxion, when I had the baseline setup at the local suspension shop they raised the ride height a few millimeters and lowered the front (raised the forks) several millimeters, probably equivalent to the 12mm you have.  I tried raising the forks 5mm and 10mm and settled on 7mm.

I am really curious about the fork setting he set -

"I'm 196 lbs / 89 kg with my gear on.  front preload: maximum, 0 lines visible, front compression: 1 click out"

Compression almost completely closed doesn't sound right.  You could try a higher viscosity oil in the compression leg and then be able to open up the damping several clicks and have more adjustable range.  Also with the preload maxed out, I'm very surprised that the suspension tuner didn't recommend different springs, again with higher rate springs you could back off the preload a little more and have some adjustment range if you should need it.  When your settings are maxed out you have no further adjustment.

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6 hours ago, betoney said:

Compression almost completely closed doesn't sound right.  You could try a higher viscosity oil in the compression leg and then be able to open up the damping several clicks and have more adjustable range.  Also with the preload maxed out, I'm very surprised that the suspension tuner didn't recommend different springs, again with higher rate springs you could back off the preload a little more and have some adjustment range if you should need it.  When your settings are maxed out you have no further adjustment.

You are correct. He did recommend thicker oil and spacers in the forks (as a budget solution) or different springs but these were the optimal settings with the stock parts. He first showed me how slow the front came up after compressing it. When he was done the bike came up nice and even front and rear when pushing it down from the saddle.

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So this question of geometry has been plaguing me.  What is the reference point for knowing whether a bike is low in front, high in back or vice versa?  It can't just be sag.  For example the rear of the GT has 5 mm more travel than the front.  Does that mean that our rider sag number needs to maintain that 5mm rear bias?  I realize that raising forks changes the handling no matter what forward or rearward bias there is.  BUT what in the world can we point to on our bike to say oh it's too high in front or too low in front?  It seems to me that we're generally after a balanced and stable machine.  Is it about rider sag?  Or something entirely different?

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40 minutes ago, Yamajank said:

So this question of geometry has been plaguing me.  What is the reference point for knowing whether a bike is low in front, high in back or vice versa?  It can't just be sag.  For example the rear of the GT has 5 mm more travel than the front.  Does that mean that our rider sag number needs to maintain that 5mm rear bias?  I realize that raising forks changes the handling no matter what forward or rearward bias there is.  BUT what in the world can we point to on our bike to say oh it's too high in front or too low in front?  It seems to me that we're generally after a balanced and stable machine.  Is it about rider sag?  Or something entirely different?

Suspension travel, rider sag and ride height/ weight bias are all separate

Suspension travel is just the measurement of how much the fork or shock can compress from fully extended, a sport bike will have very little travel and a dirt bike will have a lot.

Rider sag is a measurement of how much the suspension 'sags' with the riders weight, if the springs are too soft they will compress too much and you will be riding in the bottom portion of the measured travel, vice versa for springs that are too stiff.

Ride height is ultimately a change of the steering geometry, how quick or slow the steering reacts.  Regardless of ride height, you would want to have the rider sag set correctly before changing any other setting as the wrong spring can result in needing to make 'band-aid' fixes to compensate.

If you have a suspension shop or race course close to you ride over and have them do a baseline set-up, track day weekends always have a suspension tuner available. 

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26 minutes ago, betoney said:

Suspension travel, rider sag and ride height/ weight bias are all separate

Suspension travel is just the measurement of how much the fork or shock can compress from fully extended, a sport bike will have very little travel and a dirt bike will have a lot.

Rider sag is a measurement of how much the suspension 'sags' with the riders weight, if the springs are too soft they will compress too much and you will be riding in the bottom portion of the measured travel, vice versa for springs that are too stiff.

Ride height is ultimately a change of the steering geometry, how quick or slow the steering reacts.  Regardless of ride height, you would want to have the rider sag set correctly before changing any other setting as the wrong spring can result in needing to make 'band-aid' fixes to compensate.

If you have a suspension shop or race course close to you ride over and have them do a baseline set-up, track day weekends always have a suspension tuner available. 

I hear you.  I bought a Dave Moss membership as soon as I bought my GT this spring.  I thought I was able to dial in a good setup for me and how I ride.  I guess I'm wondering if I need to introduce fork geometry into the equation because of whether the bike is not "level" from the factory or whether I think it needs to turn quicker, or whatever.  I'm sure there is such a thing as too much adjustment especially when it comes to fork geometry.  I suppose it might be something to experiment with someday.

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Just now, Yamajank said:

I'm sure there is such a thing as too much adjustment especially when it comes to fork geometry.  I suppose it might be something to experiment with someday.

There absolutely can be 'too much' when altering the geometry.  When I was raising my forks, I tried 5mm and then 10mm and then settled on 7mm height.  That setting works for me, other riders may prefer higher or lower.  As with ANY suspension setting there is no specific number, its whatever feels good to you, that's why I never go by anyone else's settings. 

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8 hours ago, betoney said:

There absolutely can be 'too much' when altering the geometry.  When I was raising my forks, I tried 5mm and then 10mm and then settled on 7mm height.  That setting works for me, other riders may prefer higher or lower.  As with ANY suspension setting there is no specific number, its whatever feels good to you, that's why I never go by anyone else's settings. 

The way I understand it is that apart from all these other parameters there is also the distribution of the total weight of the bike and rider between the two wheels. The Tracer from the factory has too much of this weight on the rear wheel causing the front to feel light. This weight can be transferred by changing the geometry; raising the rear and/or lowering the front will put more weight on the front. At the same time this also changes the angle from vertical to the steering axis (rake). This smaller angle makes the bike steer faster which is great for racing and twisties but not so much for long distance touring.

I should repeat that I'm no expert and just learning this myself so please correct me if I'm making mistakes. My sources are Total Control (Lee parks book), the info that I gathered form the tuner and some Dave Moss videos.

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6 hours ago, petshark said:

The Tracer from the factory has too much of this weight on the rear wheel causing the front to feel light. This weight can be transferred by changing the geometry; raising the rear and/or lowering the front will put more weight on the front. At the same time this also changes the angle from vertical to the steering axis (rake). This smaller angle makes the bike steer faster which is great for racing and twisties but not so much for long distance touring.

Correct.  And that is where experimenting with different settings and personal preference comes into play.  I ride about equal amount twisties and rural highways, the fork height that works/feels best for me was +7mm.

Experimenting is half the fun because you start to see which setting has what effect on the bike, the same with all of the suspension settings, I NEVER leave home without my flat blade screwdriver or 13mm box wrench (for Penske shock compression knob) and make small tweaks from time to time.

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Interesting settings.  Still thinking about what to do going forward with the suspension.  I like sport riding when home but then go on long solo trips with luggage.   Right now I've dropped the front 7mm and it seems to work well for me.  I'm a little lighter than the OP but not much so I find his settings intriguing.  I may change the oil in out this spring and see how that works but for the street riding I do I'm happy.  I am a bit surprised at max front preload.  I'm just a bit over the stock setting ( listed in manual) and not that far away on compression and rebound.  Last time I was checking front brake dive it was not too bad IMO.  But then there is the extra 5 pounds (or more) from sitting around too much over the winter.

EDIT:  I did spend some of my suspension budget on a Tracx Flux 2 smart trainer so I can get rid of the extra weight.

Edited by PhotoAl
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Wow you got forks raised way up in the clamps ,but then maxed out the preload and the comp. witch extends the forks back out. looks like a very hard riding front and maybe on the twitchy side to me ,IMHO. But to each his own ,whatever works for you. 

MIKE

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8 hours ago, GTO MIKE said:

Wow you got forks raised way up in the clamps ,but then maxed out the preload and the comp. witch extends the forks back out. looks like a very hard riding front and maybe on the twitchy side to me ,IMHO. But to each his own ,whatever works for you. 

MIKE

I agree this does look extreme but I have to have faith that the tuner knows what he's doing. I figured that this is just how it is for my weight on this soft factory suspension to get it to normal. I did ask for optimal settings for sporty street riding and touring and the bike feels a lot more planted and easier to turn.

The front now has 31 mm static sag and 47 mm race sag. Out of 137 mm maximum travel the preload seems optimal to me, wouldn't you agree?

I still have to really understand compression and rebound. I get the theory but went to the tuner to not make mistakes so I hope that this is ok. I don't like the sound of twitchy front end so I will pay closer attention but up till now that is not how it feels to me. The only thing I know for sure on this topic is that when pushing the bike down hard and fast from the middle, front and rear now react/recover exactly the same.

 

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