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I have about 60 miles on my new (to me) mountain bike. Frame, fork, rear shock, and wheels (rim width) are all different and I'm finding myself trying to tune several things at once.
Curiously, does anybody have a system or an order of items you try to tune to get good results quickly? I'm focused on suspension and tires.
Seth
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Suspension first, set sag, then rebound to a middle ground by googling the suggested settings.
Then set tires to the right pressure, SRAM TyreWiz has a good app to help set pressure based on bike weight, rider weight, and tire size. I was surprised how low they suggested, but trusted their general values based on some videos I've watched, like BC Bike race "what tires are you running and what pressure do you run".
This is your base line to work from, and then only adjust one thing at time. I try to keep the tires the same thought the whole suspensions set up, and work on fork them rear suspension.
Multiple runs on the same trail with altered settings are best, but if it's not practical just do portions of a trail.
If I feel that my rebound needs adjusting I ride a small section with the rebound full open, and a small section of the trail fully closed, this way my mind knows what those 2 extremes feel like, and when I adjust the rebound one or 2 clicks (at the most) i know if it feels more like the way I want to go.
I use some masking tape on the fork and shock body to write down my initial setting, so you can always go back to them, its easy to get lost clicking away.
Once fork and shock are dialed this way, you can start playing with the tires. I find that if i like my suspension feel and adjust the tires, it's easy to then adjust the suspension to match the feel you want with newly adjusted tires.
Tires: run them at whatever pressures you've run in the past. Drop 1 psi at a time until you start noticing tire roll or start getting flat tires.
Rear shock: set at manufacturer's recommended sag. If you can't find a recommendation, set at 30%. Set rebound by riding off a flat curb, seated. The shock should cycle once (compress, decompress, and then settle back to neutral without further bouncing). From there, adjust rebound a few clicks in either direction to preference. Start with compression settings wide open. Dialing those in is more involved and nuanced - the internet will tell you how.
Fork: Set at suggested pressure for your weight. If no suggestion, go with 20% sag. Set your shock rebound first, then set the fork to match, so when you bounce on the bike, both ends feel similar. Start with compression settings wide open. Read internet articles to dial things in.
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Toast's recommendations are good. I'd add that you can shortcut the rebound setting by looking at the manufacturer's charts depending on the pressure you find by setting sag. That should get you a starting point to go do the curb test. Speaking of sag, set sag with compression all the way open (counter clockwise).
For compression, the best thing to do is to find a section of descending trail that you feel is pretty representative of what you typically ride. I use a trail nearby that starts with some easy jumps, then goes through some berms, a steep g-out, and ends with a couple hundred feet of 6"+ deep brake bumps and ruts. I can lap the whole thing (including climbing) in about 20 minutes. Do a lap down it with compression all open (fully CCW). Close it 2 clicks (turn CW), do another lap, and think about if it felt better or worse. If better, turn it another 2 clicks CW, and do another lap. If worse, turn it 1 click CCW, and do another lap. Repeat until you're bouncing back and forth between 2 settings. Do this for your shock first, then your fork.
I can't believe we don't have one of these threads yet.
toast nailed it.
Out of the box, I like to start on the 'maybe a little too active' side, and work my way toward damp.
I find fork sag nearly impossible to measure.Quote:
Originally Posted by toast2266
I kind of agree. I guess I should have said 20-ish percent.Quote:
Originally Posted by funkendrenchman
And really, I find the proper fork sag (much moreso than the rear shock) depends a lot on what fork it is, how many tokens are in there, where I'm riding, and what my compression settings look like. But that's all well beyond a basic starting point for the setup.
Great tips on setup.
Then, for me, there's always intermittent tune up steps that basically go something like "goddamn it, I was way too loose today, flopping all over the place. Definitely had nothing to do with being tired and hung over and riding poorly. I better tighten up my shocks and dampen things up." followed by "goddamn it, that ride felt so harsh today, I was getting bucked all over the place and jarring my teeth. Definitely had nothing to do with being tired and hung over and riding poorly. I better loosen up my shocks and get some more rebound going."
Repeat back and forth a few times per season. I find it helps keep things fresh.
Thanks all. Good info here.
You guys won’t start with bar position, saddle rails and cockpit/controls width before messing with suspension? Seems like I’d start with stock pressure charts then go right to tweaking my stem length and spacer height, bar rotation angle, brakes levers position (maybe even grip position if bar is too wide for short arms), saddle fore aft and angle ... and only THEN I’d start tweaking suspension after learning how the frame likes to be driven from a body position perspective. Maybe even tweak chainring and cassette gearing before suspension (hopefully your crankset is the length you want). But this is just an armchair perspective as it’s been years since I built my last bike (but I do have a new to me one coming in 3 days).
Well yeah, but he said tune, not fit. So I think we all assumed the bike fit him.Quote:
Originally Posted by SchralphMacchio
For fit, you start with saddle. Make sure you have your chosen crankset length if you were considering changing this. Get the height and fore-aft right. Get close by having the heel on the pedal with the crankarm in line with the seatpost and the saddle height giving you a straight leg in that position, with your heel still touching the pedal. Adjust saddle fore and aft by having your pedals at 9 and 3 on the clock, then dropping a plumb line from the bump just below your kneecap so it goes straight through the pedal spindle. Then get the nose up to the right height - high enough you don't tilt forward, low enough that it doesn't smash your junk. Cutout saddles, soft saddles, hard saddles all modify this slightly. And since all of those settings slightly move the previous one, you sort've do it in a cycle a couple times to dial it in. (Notice that if you are even close to factory recommended pressures your saddle dimensions are barely impacted by shock sag variation.)
At this point, if you have a relatively normal body, you are close. Not perfect, but close. There are some good fit videos that can help you dial it tighter.
Once the saddle is done you can do your cockpit. Some personal preference here, so figure out how wide you want the bars, how tall, how swept back, and stem length preference (not a lot of variety for this one on modern frames.) These are a bit more impacted by shock pressure, so try to get it closer before buying new parts.
Then figure out what color streamers you want.
Fair. I just think on a totally new setup you don’t want to get too deep into suspension until you really have fit setup and ergonomics dialed. And we don’t know if the OP has done all that.Quote:
Originally Posted by beece
My approach with the fork is to do the sag guesstimate to start, then just adjust the pressure based on how much travel I'm using. If I'm not using full travel when I should be, I take air out. I almost always end up taking air out, relative to the sag guess.Quote:
Originally Posted by funkendrenchman
^ Yes, agree.
Then next step on the fork: If you are blowing through travel but have to add so much air to avoid bottom out, that (a) you're too high in the fork's stroke most of the time or (b) it just feels too firm even with LSC & HSC wide open, then add a token spacer, subtract 3 psi air and try again. If you aren't ever able to use full travel unless you take out so much air the the fork is too soft/wallowy/slow even with rebound fully opened, see if you can remove an installed token, then add 3 psi air and try again. This applies to equalizing / single-pressure-setting forks ... don't follow this advice if you have an MRP or something fancy.
Depending on your shock you may have the same tuning option via volume-reducing spacer shims (Fox) or polymer bands (Rokshox).
Same here or I just start at the recommendations.Quote:
Originally Posted by panchosdad
the cannondale prophet came with a little card with all the settings how much air/how many clicks for your weight just set it all and perfect
I've never found manufacturers recommended settings to be all that close when it comes to suspension, especially forks.Quote:
Originally Posted by XXX-er
As far as fork sag, someone here posted a video that set fork sag at 30% by putting all of your weight on the bars, standing and balancing feet off the ground. That got me pretty close and is easier to replicate than trying to sit in the "attack position."
you have probably never ridden a lefty either
the settings were spot on, when we rode the bikes at interbike they asked how much you weigh and did all the settings it was pefect, other bikes not so much ferinstance the 1st Giant reign I ever seen or rode had a clapped out 5 inch fork that was leaking its way around bootleg canyon
Fork setup determines ride height, which plays into bar height. I have found that I usually iteratively tweak both.Quote:
Originally Posted by SchralphMacchio
The rest of the stuff you mentioned is more of a fit/personalization thing and happens to a large degree before the bike even hits the dirt.
Lefty was easy to setup because the damping was so terrible the settings didn't matter. :D
Taken in the context of what was around 15 years ago it was pretty good, certainly better than some leaky sacked out fork from one of the big companent makers of that time, giant puts a bike dealer on a bike with a piece of shit on the front end of the bike and the dealer just has to hope whatever shows up in the spring doesn't suck
edit: I had the lefty max so 140mm with SPV and it was pretty good, I duno what the rest of the leftys were like