Fox f29 36 rl 100mm fork problems...

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Fox f29 36 rl 100mm fork problems...

Postby stuntbikejustin » June 19th, 2013, 1:31 am

so i just picked up a hifi and it came with a fox rl.. i set it at 75 lbs as im 180 and it has bottomed out on every trail ride ive gone on. granted ive hit some small jumps but i feel like since ive bumped it up to 105 lbs it shouldnt bottom anymore but it still is... anyone else have this problem or know how i can change the compression damping?
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Re: Fox f29 36 rl 100mm fork problems...

Postby c0nsumer » June 19th, 2013, 6:51 am

Did you set the sag on it to ~25%? If so and its still bottoming out, perhaps it's having problems?
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Re: Fox f29 36 rl 100mm fork problems...

Postby iamkickstand » June 19th, 2013, 7:00 am

c0nsumer wrote:Did you set the sag on it to ~25%? If so and its still bottoming out, perhaps it's having problems?

using sag as a measurement for setting your front suspension is ridiculous. do you set it by standing on the pedals with precisely x% of your weight on the handlebars? sitting on the saddle? someone helping you balance the bike? rolling on a smooth surface? pedaling, not pedaling?

set it by riding. adjust it as necessary. It matters not one bit how much air you put in the fork to make it work for you.

UNLESS you have so much air in the fork it is unreasonably harsh over small bumps yet is still blowing through its travel.

I am not extremely familiar with the fork mentioned, what external adjustments do you have at your disposal?
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Re: Fox f29 36 rl 100mm fork problems...

Postby c0nsumer » June 19th, 2013, 7:04 am

iamkickstand wrote:
c0nsumer wrote:Did you set the sag on it to ~25%? If so and its still bottoming out, perhaps it's having problems?

using sag as a measurement for setting your front suspension is ridiculous. do you set it by standing on the pedals with precisely x% of your weight on the handlebars? sitting on the saddle? someone helping you balance the bike? rolling on a smooth surface? pedaling, not pedaling?


I do it by compressing the fork a few times to ensure the seals aren't sticking, straddling the bike using two milk crates to stand on, pushing the O ring (or cable tie) down against the seal, pedaling very smoothly around the lot in my usual riding position (with pack on), then gently rolling to a stop between the milk crates and standing back up, getting off the bike, and measuring.

If I need any brake I sit up and only very gently use the rear brake trying to avoid fork dive. It takes a few tries to get a technique down for one's self, but this works pretty well for me.

This is very similar to what Fox describes here.
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Re: Fox f29 36 rl 100mm fork problems...

Postby iamkickstand » June 19th, 2013, 7:07 am

stuntbikejustin wrote:so i just picked up a hifi and it came with a fox rl.. i set it at 75 lbs as im 180 and it has bottomed out on every trail ride ive gone on. granted ive hit some small jumps but i feel like since ive bumped it up to 105 lbs it shouldnt bottom anymore but it still is... anyone else have this problem or know how i can change the compression damping?

Can you feel the fork bottoming? Does it feel soft while riding or are you only noticing you are getting full travel at the end of a ride?

If you don't have an external compression adjustment the only way to change compression is to change the damper internally.

High speed compression is used to resist bottoming out. Low speed compression is used to resist pedal bob or "fork bob" while standing and climbing but will descrease small bump sensistivity.
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Re: Fox f29 36 rl 100mm fork problems...

Postby iamkickstand » June 19th, 2013, 7:08 am

c0nsumer wrote:
iamkickstand wrote:
c0nsumer wrote:Did you set the sag on it to ~25%? If so and its still bottoming out, perhaps it's having problems?

using sag as a measurement for setting your front suspension is ridiculous. do you set it by standing on the pedals with precisely x% of your weight on the handlebars? sitting on the saddle? someone helping you balance the bike? rolling on a smooth surface? pedaling, not pedaling?


I do it by compressing the fork a few times to ensure the seals aren't sticking, straddling the bike using two milk crates to stand on, pushing the O ring (or cable tie) down against the seal, pedaling very smoothly around the lot in my usual riding position (with pack on), then gently rolling to a stop between the milk crates and standing back up, getting off the bike, and measuring.

If I need any brake I sit up and only very gently use the rear brake trying to avoid fork dive. It takes a few tries to get a technique down for one's self, but this works pretty well for me.

This is very similar to what Fox describes here.

Setting sag still only gets you in the ball park.
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Re: Fox f29 36 rl 100mm fork problems...

Postby c0nsumer » June 19th, 2013, 7:32 am

iamkickstand wrote:Setting sag still only gets you in the ball park.


Of course, but it's the first step. If the OP hasn't done this there may simply be too little air in the fork making blowing through all the travel trivial. That's why this needs to be done / checked first.
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Re: Fox f29 36 rl 100mm fork problems...

Postby iamkickstand » June 19th, 2013, 7:39 am

c0nsumer wrote:
iamkickstand wrote:Setting sag still only gets you in the ball park.


Of course, but it's the first step. If the OP hasn't done this there may simply be too little air in the fork making blowing through all the travel trivial. That's why this needs to be done / checked first.

His 75lb number to start with seems rather low. Really depends on the fork though, so yes he should set sag to start with. His fork should also have some sort of literature that should give him a baseline to start with also.
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Re: Fox f29 36 rl 100mm fork problems...

Postby 300hp » June 19th, 2013, 8:58 am

c0nsumer wrote:Did you set the sag on it to ~25%? If so and its still bottoming out, perhaps it's having problems?



I'm with Consumer on this. Sag and compression should do different things. Per fox techs and ride camps, the way to set sag best seems to be have someone straddle your front wheel, stand up, bounce the bike, then measure sag in an aggressive, standing riding position. Consistent, repeatable, and, above all, simulates your weight distribution when you want your fork to work best.

This makes sense, as when you want the most predictability out of your fork, you're probably standing in a tough section.

Sag for weight, compression for ability and riding style.

PS chad, I'm not saying you are wrong, because on most low and mid range suspension compression and spring rate (psi) are linked, so more psi = more compression.

Suspension really just works better with a certain amount of sag (20-25 for the front) to let it do its thing.
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Re: Fox f29 36 rl 100mm fork problems...

Postby meangreen » June 19th, 2013, 9:03 am

Everything you could want to know about your fork is here:
http://service.foxracingshox.com/consumers/index.htm
Look under Service - Forks - F Series... and so on. I believe on most Fox forks Max pressure is 200PSI. Also, this is an XC fork, and it's going to bottom out on jumps unless you raise the pressure significantly above Fox's reccomended baseline. It's designed to soak up chatter from roots/rocks and moderate bumps - not really for big hits. The RL only has Rebound adjustment and Lockout. If is has an open-bath damper, you can change the compression by fiddling with different shim stacks/springs/heavier weight oil... etc - or you could pick up an F29 RLC damper - though I think the adjustment is for low-speed compression only.

You might be better off trading up to a Talas/Float which are more suited to jumps/drops etc.
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Re: Fox f29 36 rl 100mm fork problems...

Postby iamkickstand » June 19th, 2013, 9:09 am

300hp wrote:
c0nsumer wrote:Did you set the sag on it to ~25%? If so and its still bottoming out, perhaps it's having problems?



I'm with Consumer on this. Sag and compression should do different things. Per fox techs and ride camps, the way to set sag best seems to be have someone straddle your front wheel, stand up, bounce the bike, then measure sag in an aggressive, standing riding position. Consistent, repeatable, and, above all, simulates your weight distribution when you want your fork to work best.

This makes sense, as when you want the most predictability out of your fork, you're probably standing in a tough section.

Sag for weight, compression for ability and riding style.

PS chad, I'm not saying you are wrong, because on most low and mid range suspension compression and spring rate (psi) are linked, so more psi = more compression.

Suspension really just works better with a certain amount of sag (20-25 for the front) to let it do its thing.

The problem with setting sag on a fork is its wildly incosistent based on how you do it, even if you follow directions like you stated.

I don't disagree its a good starting point, but thats about all it is good for in my opinion.

He says he's using all of his travel, but he doesn't state if he's feeling the bike bottom out. Big difference there too......
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Re: Fox f29 36 rl 100mm fork problems...

Postby c0nsumer » June 19th, 2013, 9:42 am

This is a bit off topic, but one thing that helped me really understand the need for sag was finally internalizing the word "suspension". When I first started riding I thought that a suspension fork was to absorb impacts, and that's it. While this may be true for some lower end forks and those used in jumping (I'm not sure of this -- I'm not a DJ guy), for most XC/DH type use it's wrong.

The point of an ideal suspension fork for XC (and AM and DH, even though I'm not a DH guy) is to keep the front wheel suspended so that it can travel both up and down, conforming to the terrain and helping maintain front wheel traction. Thus, sag is a very important setting, else your fork won't be able to appropriately extend from its normal riding position and keep the tire in contact with the trail.

My personal preference for setting up a fork for my XC riding is to have about 25% sag, use most (maybe 80-90%) of the travel during my normal riding, which includes jumping off of little things and taking small drops ala PLRA / Poto / Highland. I like it to go through its full travel and bottom out only when I do something dumb or particularly aggressive and I want the extra bit of squish to help keep me from going over the bars. This has worked out nicely for me.
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Re: Fox f29 36 rl 100mm fork problems...

Postby iamkickstand » June 19th, 2013, 10:00 am

c0nsumer wrote:My personal preference for setting up a fork for my XC riding is to have about 25% sag, use most (maybe 80-90%) of the travel during my normal riding, which includes jumping off of little things and taking small drops ala PLRA / Poto / Highland. I like it to go through its full travel and bottom out only when I do something dumb or particularly aggressive and I want the extra bit of squish to help keep me from going over the bars. This has worked out nicely for me.

This.

Maybe I overlook sag because I am more concerned about some of the other stuff, but I also have forks that have a fair amount of adjustment, so I can dial in both how my suspension feels over small bumps, as well as over large hits.

I like to use about 75% of my travel for normal XC riding and know that i have 25% ish left over for a big mistake.
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Re: Fox f29 36 rl 100mm fork problems...

Postby bergsteiger » June 19th, 2013, 3:47 pm

c0nsumer wrote:
The point of an ideal suspension fork for XC (and AM and DH, even though I'm not a DH guy) is to keep the front wheel suspended so that it can travel both up and down, conforming to the terrain and helping maintain front wheel traction. Thus, sag is a very important setting, else your fork won't be able to appropriately extend from its normal riding position and keep the tire in contact with the trail.
.


I get where you are going with this and land at in the same spot, but I look at it as the suspension is suspending you and the most of the bike, allowing the wheels to track the ground as well as absorb bumps/hits.

pre actual suspension, YOU were the suspension and you used your arms and legs to do all the work of absorbing and trying to have the wheels conform to the ground (or not either intentionally or not)

So yep sag is a starting point to allow the suspension to move in both directions from that point. And yes it can be a pita to do and can be difficult to do repeatability wise
But yes, everyone has good points, we need more info.
- bottoming out harshly during rides
- using up all the travel but not noticing, this is actually the general goal.
- ???

in the past on one fox I had I had to run it with a bit higher pressure to keep brake dive in check, this was with an R level so without cracking it open to play with oil weights. This was detrimental to the small bump compliance.
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Re: Fox f29 36 rl 100mm fork problems...

Postby stuntbikejustin » June 20th, 2013, 1:13 am

i set my sag that was 75 lbs.... that was in riding position... anyway i bumped it up to 110 psi and changed the oil and checked all the o rings..... its pretty harsh but i rode the poto today and used about 90% so i was happy... i might drop to 105 or 100 n try torn shirt on friday... but my sag is like 5mm at this psi.... sooo yeah i miss my reba... or i need an rlc theres no compression adjustment.. just pressure.... sucks dual air and compression is the way !
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