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Author Topic: Fork tuning for full travel  (Read 2805 times)

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scooter

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Fork tuning for full travel
« on: December 13, 2007, 10:32:06 PM »
Hail, I took the Trance out for her second ride today and have been playing with air pressure in the Reba fork. I put a tye wrap on the fork to monitor max travel during the ride. Ride #1 was 120 psi and all but maybe 5 mm travel was used. Today ride #2 used 130 psi and used only 85mm of the available 100mm of travel. Both of these rides were at Boyette and consisted of several passes thru the Abyss and Pandemonium trails to ensure the Reba was getting a good workout. 130psi is obviously too much and 120psi seems perfect other than the fact I am leaving 5mm on the table. So what I am pondering is when it is said you want to access all available travel does this mean getting the full 100mm? At 100mm, is the fork bottoming out? is this detremental to the fork? Is that 5mm I am not using a good saftey? or should I consider running 115psi?

Offline Garry

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Re: Fork tuning for full travel
« Reply #1 on: December 14, 2007, 08:51:37 AM »
You don't want to bottom out of all of your travel.  The 5mm should be fine for that day when you hit a drop a bit harder than you normally do.  Besides, for most all of what we ride in Florida and much of Georgia you only really need about 80mm.  It's nice to have 100mm, but we don't often hit stuff like what is found out West or up in the northern mountains.  I would set it so that out of my available travel I still have room for a big hit without bottoming out.

Offline Gregg

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Re: Fork tuning for full travel
« Reply #2 on: December 14, 2007, 10:51:06 AM »
I have my Reba set for 80 psi up and down......The factory recommendations are WAY to high. Not only have I personally experienced it, but if you read the reviews on MTBR.com, you will hear that this is a common experience. Once you get it dialed.....Reba is so sweet! ;)

scooter

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Re: Fork tuning for full travel
« Reply #3 on: December 14, 2007, 11:44:47 AM »
Yeah, I remember the time at the boat ramp you let me tool around on the Kona and it felt like a ridgid fork to me, almost like it was locked out. I think you said you were running 110psi positive that day not sure what negative pressure you were running so that and all the feedback I have gotten on the web told me I would need to decrease the Rockshox suggested psi settings. I first tried the sag set up which put me at 120 psi. At this pressure the fork was super plush and even at 130 psi it is still a very plush feel. It seems on my Reba the Rockshox suggested pressures are dead on. I found that if I ran to low a negative pressure the fork became to ridgid and after some touchy feely I think 10 psi less in the negative chamber than what I am running on the positive side gives me what I am looking for. I think what Garry said about not botting out the fork makes perfect sense so 120psi is probably a bit low since it only allows for another 5mm of travel in the case of a BIG hit, so I will think I will play around with 130psi positive and 120psi negative. Next comes dampening tuning, buts thats a whole other topic ;D

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Re: Fork tuning for full travel
« Reply #4 on: December 14, 2007, 03:04:27 PM »
I have never bottomed my fork out.

That day that you rode it, I had just gotten it back from the rebuild, so I was playing around with the pressure. I brought it down in 5 psi increments, until it both felt plush and was firm enough that I wouldn't bottom out on features like the whoops on bridges. I am not sure if the ride characteristics would change a lot if there was suspension in the rear, like you have. Perhaps Garry would know that since he rides both a hardtail and a fully.

I also have the rebound set on the quicker side.

scooter

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Re: Fork tuning for full travel
« Reply #5 on: December 14, 2007, 03:08:27 PM »
Yeah, I am currently half a turn back from full RABBIT ;D rebound.

Offline Leons_Bad_Side

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Re: Fork tuning for full travel
« Reply #6 on: January 08, 2008, 12:28:44 PM »
I'm running a Reba on my S-Works Enduro and I was wondering what weights(not trying to get personal) you guys are approx. I'm about 170 and was trying to set up my fork. I don't want it to soft but of course I want to gain some benefit from it. Also I'm curious in what situation would the lockout feature be useful on the front. I can understand the usefulness of the lockout feature on the rear especially while climbing but I'm a little shaky on the front lockout.
Pete
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scooter

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Re: Fork tuning for full travel
« Reply #7 on: January 08, 2008, 01:27:41 PM »
Hey Leon, I pretty much have mine dialed in. I go about 175 pounds currently. and am running 130 psi on the top and 120 on the bottom of my Reba. This left me just a small amount of unused travel my last couple of outings. Try what I did, put a tye wrap around the fork stantion ride hard and when you get home check out the amount of travel used. I want to leave a little in reserve in case I take a big hit.

Offline Leons_Bad_Side

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Re: Fork tuning for full travel
« Reply #8 on: January 08, 2008, 02:33:34 PM »
Thanks Scooter I'll try that. I think I was going to much by what the book tells me and I had to much pressure in both the pos and neg sides of my fork.
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Offline Leons_Bad_Side

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Re: Fork tuning for full travel
« Reply #9 on: January 08, 2008, 06:49:58 PM »
Ok now a couple of other questions. I have two high pressure pumps for my fork and shock. If I pump my pos side on my fork to 130psi and take the valve off and put it back on it comes up to about 100psi. Same on the neg side if I pump it up to 120psi and take the valve off and then put it back on I end up with about 85psi. Is there a way for me to take the fill valve off of the stem without letting so much pressure out? Do I just need to figure out how much escapes and put it up that much more? Also I see that you are talking about the Reba having 100mm of travel but I can adjust mine from 85 to 115mm. I have it set to full travel 115mm.
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Offline Garry

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Re: Fork tuning for full travel
« Reply #10 on: January 08, 2008, 07:25:52 PM »
Also I'm curious in what situation would the lockout feature be useful on the front. I can understand the usefulness of the lockout feature on the rear especially while climbing but I'm a little shaky on the front lockout.
Pete

The lockout on the front offers a stiffer, faster climbing ride. When approaching a climb lockout the fork.  Climbing causes you to lean forward and lose power from the active suspension of the fork.  By locking the fork and rear out you are able to lean into the climb and power through each pedal stroke and then make it fully active again on the down side to absorb all of those fast bouncing decents.

scooter

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Re: Fork tuning for full travel
« Reply #11 on: January 08, 2008, 07:59:09 PM »
I think you should try finding that travel sweet spot I talked about earlier with your particular pump. I wouldn't focus so much on a psi # as 130 psi on my gauge could 120 on yours. In other words find your pumps psi that delivers your travel sweet spot and top it off every preride to that pumps psi#

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Re: Fork tuning for full travel
« Reply #12 on: January 08, 2008, 09:01:36 PM »
I set both of mine a little harder than recommended because I like a little stiffer ride.

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Re: Fork tuning for full travel
« Reply #13 on: January 09, 2008, 07:23:35 AM »
About the pressure loss with the pump, I don't have an air shock in the front but I do in the rear. I could be mistaken but the pumps are positve retention release ( I think that's the term),so the pressure remains the same as you release the pump. When you screw it back on it fills the pump and that's where the pressure loss comes from. The same thing happens with my Rear Fox shock. When I asked Chainwheel Drive about it that was what they told me.
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Offline Leons_Bad_Side

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Re: Fork tuning for full travel
« Reply #14 on: January 09, 2008, 08:01:16 AM »
Ok, cool. That makes sense.
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