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suspension travel query
hi all, after many years on an hardtail, ive finally upgraded to a dually. during my first ride i got a little overconfident and scratched the new bike (shock horror) and myself, but all in the name of funn. however im having trouble setting sag. using a ruler im setting at around 12mm in the rear shock - less than the recommended range but yet still seam to use almost all of the travel, this is on a mostly benign firetrail. or is this normal. as for the front i get only 4-5mm it seems - had it at around 100psi and decreased this to about 80 with nil effect on the sag in descent mode but stil using a lot of travel for the trail i thought in trail mode . also i noticed a clank when going of a gutter in climb mode- i forgot i was in climb at the time or could it be the rear derailuer which has the clutch? cheers. dom
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depends on the bike, but generally XC (100-120mm) 10-20% sag pending on personal preference, AM (140-160mm) 15-25% sag. But certain bikes have certain requirements due to their suspension design. So some more specs on the bike will help give a more accurate answer. A lot of it comes to personal perference also.
hey muvro, got a santa cruz bronson - 150mm travel - riding it feels very smooth compared to a hard tail, but wasnt hitting and big jumps or the like, just trail chatter and it seems to use a lot of travel. having said that, climbing was a lot easier than i thought it would be. have heard comments that for climbing speed nothing beats a hardtail, but i now disagree - felt it climbed better and faster than my old hardtail.
I've been riding duallies for a few years and bought my first brand-spanking-new one last month. The first few always had a few km on them.
Like you I've had some issues with getting the suspension the way I like it and I think part of it is stiction from bushes and wiper seals needing to bed in, although the fork in my case may need some attention from the distributor as it doesn't seem quite right. That happens sometimes it will get sorted.
Starting sag for a 4-5 inch travel xc bike should be around 25%. You can reduce that to 20% for pedaling efficiency on a smooth course like the Mont 24 or up it to 30% (less pressure) for more technical trails. If you're blowing through travel too easily you can up pressures too.
Another option is to insert a volume reducer so that it ramps up more in the second half of the travel. In the case of my Lefty that was ramping up way too much so took it out which has improved it considerably for now. You should expect to use full travel once or twice per lap. So long as the bottoming out is not harsh and you're just seeing the o-ring up the end of the shock shaft that should be fine.
It is also little known that increasing rebound damping (that is, slower) also increases compression too, so perhaps you should take a look at that as it may help the shock support you better through the mid stroke. It is better anyway to err on the slow side for rear rebound (and on the fast side for the front) unless you like going over the front off water bars
Hope that helps.
cheers hawkeye- wish i had of known about the rebound yesterday - it might of stopped me going otb - but prob not. on that remark - do you set sag with no rebound and set rebound after sag - or set sag on full rebound ?
Sag setting by those in the know.
http://www.mojo.co.uk/techtips.html
I always found that the front end way too soft despite the recomended amount of sag until I set it up using these guys method.
Just be aware the mojo tips are focusing on DH. The reference to a coil spring on the rear is the hint. You would use less sag for xc and endurance events/rides. But the points on body positioning and actual shock and fork stroke are good ones.
HIstorically I've got tended to measure mine with the rebound set where I ride it but I know others wind it fully off, set the pressures, then put it back. Just don't do what I did and forget to dial the rebound back up. Nice way to give yourself a serious fright
A volume spacer kit is the best money you can spent, even if it is $50 for 3 nylon spacer blocks. As Hawkeye said this can make a big different to the ramp up and progression of the shock. Really easy mod to do. Just done it to my high volume fox RP23. Plenty of info on the net.
HI,
I might be able to help a little more, but ill need some more info.
Im not sure if i missed something but I dont know what bike we're talking about ?
Also your weight would help, the fork and shock model ? evo, factory ? performance ? float ctd ? and what velocity tune the rear shock has..
The clank going off the gutter in climb mode code be a few things depending on the shock model, but most likely it was oil pushing through the shim stack.
Q. I understand exactly what it does but cannot fathom why every other person seems to recommend doing something to a brand new $6000 bike that so radically changes the behaviour of the suspension.
Surely the manufacturer (Santa Cruz in this case) spend a lot of time & effort in speccing the right shock for their frame.
Imo unless you are an unusually heavy or light rider or have a significantly different riding style to the norm shouldn't the shock work great as it comes?
Enlighten me
Just be aware that some VPP designs are quite notorious for air shocks blowing through their travel very easily over "normal" riding conditions. I've had to switch out to a coil shock (from a dhx air) on my nomad for that very reason. Although I note the online discussions have mainly been around the pre-2010 model nomads rather than other VPPs in general.
edit: VPP's rear axle arc moves rearward in the first 1/3 travel stage (the sag stage) and then moves in a forward arc in the "plush" stage of travel. the "active suspension" is really maintaining the distance between the axle and BB during the first 1/3 travel. Supposedly this means you should be able to use any shock instead of having to "pair" the suspension design with an appropriate shock.
Unfortunately the way VPP achieves this "S" rear axle arc is that geometrically, upward forces on the wheel force the lower wishbone to pivot before the upper wishbone, so the upper wishbone "holds out" until the bumps force it to "give way" - and once it does, it does so easily and quickly. Air shocks are the immediate "casualty" of this merely because they aren't as linear as coil shocks. I've heard SC have been trying to limit the issue, *possibly* by reducing the total wheel arc travel in the last 2/3.
Always set sag with rebound all the way off as well as any platform adjust e.g propedal etc.
Don;t get too hung up on it though - adjust your pressure until it feels "right". As long as youhave enough sag to keep the wheel planted on as the bike unloads you'll be fine.
When riding a hard tail I tend to land back wheel first unless there is a nice lander. This minimises the drop height.
However on a dually this can easily blow through all the rear travel and on a bad day alter the bike geometry so much the fork breaks rather than compressing.
Best to land front wheel first or both together.
On a 150mm dually I ran 30% rear 20% front (30mm) sag with preference for going down. Always set sag in attack position, standing on pedals with weight on bars (none of that XC off the back seat stuff otherwise fork will be mush or stiction will control sag not your weight). Rebound slightly faster on front than rear. Moderate amount of bottom out limiter. Compression damping set to control brake dive and to also hold the bike geometry through a rock garden.
If rebound is too slow you will also blow through all travel to easily as bike gets stuck down in travel.