I have a manitou sherman front fork. I am 180lbs. How much air should I have in the chamber. At least a point to start from. I rode yesterday, and on a 4' drop, it would bottom out. A friend said he thought it needed 50psi. I checked it and it was at 60psi. So I pumped it up to 80 and rode and off the same drop there was pretty much no difference. Same bottomage. I think something may be broken inside. I know these are not a very great shock but it has not much hard riding on it. What are common things that go bad with these? It is an 04 sherman slider. The headset seemed to loosen up too. I tried to tighten with not much luck.
How much air in manitou sherman?
- Thread starter lunendan
- Start date
I'm not much on Air forks but from what I've learned, you need to set your pressure according to the sag amount.
Ideally, you want a 20% sag (how much the fork compresses when you sit on the bike and don't move).
Quickest way to find out how much sag you have is to put a zip tie around one of the stanchoins, push it down toward the stanchion wipers(seals) and sit on the saddle with your feet off the ground (have a buddy or a wall help you keep your balance).
Set your air pressure till you get to the 20% mark. If you have a 100mm fork, you want a sag of 20mm, etc... From there you can dial into what feels best. Good luck.
Ideally, you want a 20% sag (how much the fork compresses when you sit on the bike and don't move).
Quickest way to find out how much sag you have is to put a zip tie around one of the stanchoins, push it down toward the stanchion wipers(seals) and sit on the saddle with your feet off the ground (have a buddy or a wall help you keep your balance).
Set your air pressure till you get to the 20% mark. If you have a 100mm fork, you want a sag of 20mm, etc... From there you can dial into what feels best. Good luck.
yep it is. Turn the volume adjuster knob in a bunch. Check to make sure your sag is <30%, and then just keep pumping up the pressure i guess? SPV shermans never feel good FYI.
i weigh 200 and ran 45psi with one turn of volume.
Retro, you weigh 20lbs more than me and run 45psi? So why does mine bottom with 60psi then 80psi? What are you turning that you talk about volume. I am used to the regular terms like preload, damping, rebound adjustments. What is volume? I only saw one knob on the bottom of the fork leg and it only turns about 270 degrees. It doesn't turn all the way around. I think it is the damping.
come on..the least you can do is go the mfg web site and find the owners manual and figure out what adjustments your fork has. Is it truely easier to post here and have 15 people give you 15 different and most likely incorrect answers??
Springs control sag as well as the force needed to move the shock/fork throught the travel. If you are bottoming, you need a stiffer spring. Forks come stock with a spring for an 'average' rider..ie 165lbs.
The air that you are putting into your fork controlls the SPV damper. The more air pressure, the more damping. There is a 16mm 'bolt' on top of the same leg that is a volume adjuster (of that same air) to adjust how progressive the dampiing is through the travel.
Manitou has good tech info on their web site. Go look up your fork and learn a bit.
i agree with dave p. if your not familiar with the functions of your fork than you really need to read you owners manual and check manitous web site for set up help. and yes i always ran 40 to 45psi in the spv. any more than that and it felt that it made it stiff feeling. but i run a travis 180 now and don't have worry about air pressures anymore.
Davep putting the smack down on my laziness. Right on. I actually did get the owners manual and repair manual off their site last night right around the same time I was posting. It wasn't the easiest site to find but I got it finally. I completely wanted to read up and learn about it. But I bought the bike used and got no paperwork. I have actually done a total rebuild to my cr250 front fork years ago but am new to these. I was just looking for a post like, this x broke, weak from factory, blah blah. I will read up and gain some knowledge. You downhillers are rough on newbies. Thats good though.
"Stay off my wave! Goon trying to drop in"
"Stay off my wave! Goon trying to drop in"
Well heres one for you...I have a sherman slider, weigh 145lbs, and have been running 120-140 PSI for quite some time, that was the ONLY way I could get it so I wont bottom it.
However, when I went to whistler I put it to 70 PSI so I could have quick rebound and better absorbsion on the brake bumps, but on most of the bigger jumps, like the 4X ones and double dimonds, the fork would bottom out just from the G's hitting the jump, and sometimes in berms too.
I need to do ALOT of adjusting to get it right I think...I just dont think Manitou designed the fork very easy to adjust.
However, when I went to whistler I put it to 70 PSI so I could have quick rebound and better absorbsion on the brake bumps, but on most of the bigger jumps, like the 4X ones and double dimonds, the fork would bottom out just from the G's hitting the jump, and sometimes in berms too.
I need to do ALOT of adjusting to get it right I think...I just dont think Manitou designed the fork very easy to adjust.
I read the manual and they say not to exceed 100psi. The amount of air controls the damping, not the preload. They sell heavier spring kits for the left leg for more preload. Then, the big nut around the air screw on the right leg controls the damping from half stroke to bottom. Turn it one way and it will be way less likely to bottom out. It will slow down the bottom half of the stroke considerably. Turn the other way and it will be plush/soft and likely to bottom out. I am going to try adjustments Thursday but I think I will need the 170-190lb spring.
Sorry, I did not mean to come across so agressive, it is just hard to explain this kind of thing if the user does not understand the workings or uses incorrect terminology....but you do have a much better understanding of the fork now..
In my experience, the springs in that fork was fairly soft, I think that will help quite a bit. (I am 185 and could never run the stock spring in my older sherman slider (pre SPV)). Play around with the adjustments so you can get a 'feel' for what they do. The fork could most likely use a change of bushing lube as well (might want to do at the same time as the spring)
Muddy, look at the tech articles for the fork. It sounds like maybe the spv valve in your fork is not working correctly (in my experience SPV dos an acceptable job of preventing bottom out (with propper spring), althought generally, it feels quite sticky and has poor low speed IMHO).
Sounds like the spv valve is stuck, causing a loss of damping (simple two piece gizmo with o-rings). This happens often and is a simple check/fix..all outlined on the site in the tech documents.
In my experience, the springs in that fork was fairly soft, I think that will help quite a bit. (I am 185 and could never run the stock spring in my older sherman slider (pre SPV)). Play around with the adjustments so you can get a 'feel' for what they do. The fork could most likely use a change of bushing lube as well (might want to do at the same time as the spring)
Muddy, look at the tech articles for the fork. It sounds like maybe the spv valve in your fork is not working correctly (in my experience SPV dos an acceptable job of preventing bottom out (with propper spring), althought generally, it feels quite sticky and has poor low speed IMHO).
Sounds like the spv valve is stuck, causing a loss of damping (simple two piece gizmo with o-rings). This happens often and is a simple check/fix..all outlined on the site in the tech documents.
Mine says it not recommended to exceed 150psi...and Davep, thanks...all my buddies who have tried the fork agree with you, and think something broken and not working how it should. I got the fork for free from Manitou though, to replace a kingpin I broke, so my guess is its a returned fork, or something.
I plan on taking it into my shop sometime, I'll ask some of the mechanic's at the one I work at though before hand.
Dave, no sweat on the razzing. I come from Massachusetts and ball busting is considered the norm. You are right, I should have researched first. I think soft spring is the biggest factor. I am going to play around tonight a little, but still order the harder spring. The drops are only getting bigger the more comfortable I get on the bike. I just thought something was wrong with it bottoming out from an easy 4 footer. I'm just too heavy for the spring, plus not adjusted properly. Thanks for the info fellas. I'll post some results after I play around.
I wouldnt worry to much about bottoming out though...like I was saying, I was in whistler 2 weeks ago doing all the trails (double dimonds, dimonds, ect.) and even though my fork bottomed out on about 75% of the stuff, it wasnt super bad. I just tried to not land to hard on my front and and that way the bottoming out didnt affect me/my hands to much.
de-evolve your fork. There are good threads out there on the process, which really is quite easy with some basic tools. I hated the feel of my Sherman before I removed the SPV check valve, and now it's actually responsive to smaller hits. If you're just running stunts / drops, then I guess the limitation of pedal induced bob afforded by the SPV is positive, but for general riding, my de-evolved fork is a huge improvement.