Front Susension

[the razor]

I have an 07 CBR1000RR. I had the suspension tuned up on may of this year, but I noticed that my front suspension is bottoming out on me. Started happening like a month ago. I do not want to take it to the place that did the tune up. I just want to see if one of the readers can give me a hint of why it is happening and what should I do. Should I let up the compression and how much. Also, what effect will it have on my front suspension. Thanks to you for your input. By the way, I bought the bike new with 0 miles out of the dealer. as a matter of fact I picked it out of the Box. November will be a year old.

55 and stay alive.

The razor.

[khp]

I have an 07 CBR1000RR. I had the suspension tuned up on may of this year, but I noticed that my front suspension is bottoming out on me. Started happening like a month ago. I do not want to take it to the place that did the tune up. I just want to see if one of the readers can give me a hint of why it is happening and what should I do. Should I let up the compression and how much. Also, what effect will it have on my front suspension. Thanks to you for your input. By the way, I bought the bike new with 0 miles out of the dealer. as a matter of fact I picked it out of the Box. November will be a year old.

55 and stay alive.

The razor.

Razor,

 

There are amble room for questions here - first, what did the shop do to tune up the suspension?

Are we talking road or track riding here?

Also, how have your riding style or speed changed since you had the tune-up done?

What is the current setting of the front fork compression (how many clicks out from maximum damping)?

Do you know why you're bottoming out the fork? (harder braking or simply riding harder everywhere?)

 

There are at least two venues of changes: adding compression damping, and adding oil to the front fork.

Adding a couple of clicks of compression damping will make the front fork dive less under all situations where the weight it transferred forward. This could be detrimental to what you want/need in the mid-stroke.

 

If you want to keep the damping profile in the mid-stroke, adding a bit of oil (say, 10mm) will make the force required to compress the front fork more progressive.

 

Regards, Kai

[ozfireblade]

I have an 07 CBR1000RR. I had the suspension tuned up on may of this year, but I noticed that my front suspension is bottoming out on me. Started happening like a month ago. I do not want to take it to the place that did the tune up. I just want to see if one of the readers can give me a hint of why it is happening and what should I do. Should I let up the compression and how much. Also, what effect will it have on my front suspension. Thanks to you for your input. By the way, I bought the bike new with 0 miles out of the dealer. as a matter of fact I picked it out of the Box. November will be a year old.

55 and stay alive.

The razor.

Razor,

 

There are amble room for questions here - first, what did the shop do to tune up the suspension?

Are we talking road or track riding here?

Also, how have your riding style or speed changed since you had the tune-up done?

What is the current setting of the front fork compression (how many clicks out from maximum damping)?

Do you know why you're bottoming out the fork? (harder braking or simply riding harder everywhere?)

 

There are at least two venues of changes: adding compression damping, and adding oil to the front fork.

Adding a couple of clicks of compression damping will make the front fork dive less under all situations where the weight it transferred forward. This could be detrimental to what you want/need in the mid-stroke.

 

If you want to keep the damping profile in the mid-stroke, adding a bit of oil (say, 10mm) will make the force required to compress the front fork more progressive.

 

Regards, Kai

 

 

Agrees with Kai.

Just a couple of questions. The bike is an 07? so the oil is really 3 years old and the fork seals weren't moving in the box for 2 years? check your fork seals and is there any leaks or puddles under your bike in the morning? Or drop your fork oil may just be old?

 

Initally (cold) does your suspension feel fine then as the day goes on feels like its bottoming out more? This may be because the fork oil is heating up, from riding hard and working the forks more, becoming thinner making your suspension softer causing the bottoming out. If this is the case maybe a half turn off compression may help, when the bike has warmed up or throughout your session.

 

Not a suspension guru may help though

 

Dylan

[the razor]

Thank you guys for your input. The setting is, if I am not mistaken, 1 3/4 turn out for compresion and 1 for rebound. It just happens when I break hard and after a few miles. I do most of my riding on the street. The forks are not leaking. (seal); But I think the setting was for turning fast. (track).

I am going to do 1/4 of a turn out for compresion and see how it works. I have 6000 miles on it. I will let you know how it feels when I go riding this weekend. Also my riding improved (a bit faster) since I took level one in August.

Much better on the corners. Thanks again Kai and ozfireblade (Dylan). Any other comment will be appreciate.

I will keep you posted. I will have the oil change next year since I have maybe 2 more month of riding and then I will store it. The razor.

[johnnyrod]

The oil will be pretty bad by now I should think, so yes do change it at the start of the season. Before you start on damping, check the spring weight is correct for you (typically the stock springs are good for up to around 200lb rider),and also check the sag (preload) is set right. There are various ways to do this but the simplest check is that it compresses by just over an inch with you sat on it (from fully extended). If this is more or less right then you can start worrying about damping but really unless you brake hard then odds are the spring side (spring weight and preload) needs checking first.

[the razor]

The oil will be pretty bad by now I should think, so yes do change it at the start of the season. Before you start on damping, check the spring weight is correct for you (typically the stock springs are good for up to around 200lb rider),and also check the sag (preload) is set right. There are various ways to do this but the simplest check is that it compresses by just over an inch with you sat on it (from fully extended). If this is more or less right then you can start worrying about damping but really unless you brake hard then odds are the spring side (spring weight and preload) needs checking first.

.

Thanks Johnny Rod.

The sag is the correct one for my weight. But I will double check it any way. Thanks for your input.

I will do the compression and see how it feels. Next year when I change the oil (fork) I will have it set up again.

Thanks again.

The Razor.

[the razor]

The oil will be pretty bad by now I should think, so yes do change it at the start of the season. Before you start on damping, check the spring weight is correct for you (typically the stock springs are good for up to around 200lb rider),and also check the sag (preload) is set right. There are various ways to do this but the simplest check is that it compresses by just over an inch with you sat on it (from fully extended). If this is more or less right then you can start worrying about damping but really unless you brake hard then odds are the spring side (spring weight and preload) needs checking first.

.

Thanks Johnny Rod.

The sag is the correct one for my weight. But I will double check it any way. Thanks for your input.

I will do the compression and see how it feels. Next year when I change the oil (fork) I will have it set up again.

Thanks again.

The Razor.

 

I just did an extra 1/2 turn out and it worked nicely. Thank you guys for your tips.

[faffi]

More damping will not prevent the suspension from bottoming under braking, it will only make it take a bit more time and also make the bottoming gentler and smoother (less chance of a rebound). It is the spring that supports the bike. If you have set the static sag correctly with a rider, there is no guarantee that the springs are stiff enough. You could preload the springs enough that the bike hardly settles on its suspension on its own, and then drops the required 1.5 in when you sit on it. That's a clear case that the springs are way too soft. Ideally, the springs should settle almost an inch on its own and then the final .5 in by our weight.

 

If you do need a stiffer spring but don't want to pay for it, you can upp the oil LEVEL. This will reduce the air gap above the oil, giving the trapped air less room. This will make the interanl pressure rise quicker, and since the air works as a spring, will make the fork stiffer and more progressive. At the most extreme you'll go into hydro-lock before you've used the whole travel.

 

There are typically two extreme schools when it comes to suspension; those who believe in realtively soft springs and lots of compression damping along with little rebound (BMW back in the old days, for instance, and racer Helmut Dähne who took it to the extreme back in the 70s) and those who believe the bike should rely primarily on springing to support itself with little or no compression damping and lots of rebound to control the stiffish springs. Most bikes sit somewhere in between the two extremes. I prefer the stiff spring/low compression damping setup, but only if you have two or three different spring rates (preferably not progressive springs, but springs with mechanical travel limits for each spring).

[the razor]

More damping will not prevent the suspension from bottoming under braking, it will only make it take a bit more time and also make the bottoming gentler and smoother (less chance of a rebound). It is the spring that supports the bike. If you have set the static sag correctly with a rider, there is no guarantee that the springs are stiff enough. You could preload the springs enough that the bike hardly settles on its suspension on its own, and then drops the required 1.5 in when you sit on it. That's a clear case that the springs are way too soft. Ideally, the springs should settle almost an inch on its own and then the final .5 in by our weight.

 

If you do need a stiffer spring but don't want to pay for it, you can upp the oil LEVEL. This will reduce the air gap above the oil, giving the trapped air less room. This will make the interanl pressure rise quicker, and since the air works as a spring, will make the fork stiffer and more progressive. At the most extreme you'll go into hydro-lock before you've used the whole travel.

 

There are typically two extreme schools when it comes to suspension; those who believe in realtively soft springs and lots of compression damping along with little rebound (BMW back in the old days, for instance, and racer Helmut Dähne who took it to the extreme back in the 70s) and those who believe the bike should rely primarily on springing to support itself with little or no compression damping and lots of rebound to control the stiffish springs. Most bikes sit somewhere in between the two extremes. I prefer the stiff spring/low compression damping setup, but only if you have two or three different spring rates (preferably not progressive springs, but springs with mechanical travel limits for each spring).

 

Thanks for your input Eirik. For the time being it is O.K. I just have two more month of riding.

Next year (spring time) I will have the oil changed along with the seals and the springs. I will have it set up again for my weight and style of riding.

Interesting comment though which is appreciated.

The razor.