The rider of this bike is about 185 lbs and has approximately 18 hours on the bike. No attempt at any suspension changes had been made until yesterday.

The bike did seem to be hitting a little hard on landings, especially the front, and the rider complained of arm pump from vibration and shock thorugh the handlebars. Keep in mind, this rider is almost hopeless at describing what he likes or doesn't like about suspension settings.

First order of business was to check the sag. Book says 105mm, but his was around 70mm. The stock purple spring is installed.So we adjusted it for 105mm. It was way too soft. It appeared too soft, rear ride height was way too low, and rider complained he wasn't getting the air he wanted over jumps. So more adjustments were in order and he eventually felt comfortable with it set to about 85mm.

1/ My question is if this 85mm sag is common, or is he just so used to the old 70mm of sag, so he can't get his head wrapped around the recommended setting of 105mm?

And since I'm posting, I'll add that no changes have been made ot the rear shock, but we did play around with the front fork settings. Compression started stock at 11 clicks, trying 13 proved too soft, but he liked 12.  (Personally I wonder if he can tell, but i have to go with his feedback regardless). Rebound, which is stock at 11, he seemed to prefer 10. He seems to like a little kick up of the front and doesn't like the mushy feeling of when the front wheel stays planted on the track (which seems confusing ot me, but i don't race).

2/ Bascially, I'm open to suggestions and would like to hear opinions and any recommendations on all suspension settings. Please include your weight though, so I have an idea of how to compare things.

Thank-you.

Suspension is individual to a rider and machine.  There are some guidelines to get you close, but what one rider likes, another may hate. I think the stock springs are for a 160 lb rider so heavier springs may be the first place to start.  Check Race Techs web site. They have a spring calculator to help find what rate he should have. And like I tell my riding buddies. don't be afraid to turn the clickers.  You can always turn them back.  I have an 06 and only trail ride, but I turned all my clickers two settings softer (weird how it worked out that way) ,comp and rebound, and I love the way it handles. I bought the bike used so I don't know if any suspension work was done, but it works for me.

Seems strange. I was able to set sag on my 2010 and my 2012 with the stock shock spring. Ive ranged from 180-190lbs. The stock shock on my 2010 was Yellow and 2012 is red, didnt know they did a purple spring, but if its stock i should allow adjustment of the recommended sag for his weight. 70-80 mm of sag seems like way too little. Id try and set it at 100mm+ and get him used to riding it like that for a week or two.

i have had similar experiences as Mike's, setting up a 2010 rmz450 for a 170lbs rider. i had to drop the spriong rates front and back and lose some oil in the forks to make him happy (clicker settings differ depending on track conditions). the stock stuff should be good for 175 to about 185lbs depending on your speed, so springs should be good. are you measuring the sag with rider sitting on bike in attack position (race sag) or are these static sag measurments (bike sag without rider aboard)? 70mm is WAY too little and will cause the shock to "top out" too soon on bumps and loose traction under acceleration. 100mm of race sag is minimum for track IMO. the spring rates are good for his weight, so try first dialing in the shock and then moving to the forks. what level of riding is he at? i have also never heard of a purple spring (purple paint on the spring is more plausible)

Well, well, well.... Lots of replies. I must have my auto e-mail notification disabled, so this is a nice surprise.

I do agree that the rider needs to give the full 105mm sag a chance, but on the other hand, when he's on the bike, it does give it a nose up attitude. He was out today with it at 85mm, and came back happy. So he's getting used to it in the right direction anyway.

It really seems I'd have to do somehting to shorten the front forks with the rear spring set to 100mm of sag. Not sure what to do there... if anything.

As far as the spring colour goes, it actually appears more red than purple. If I had to call it a name, I'd say burgandy. But in the page below, you can see the stock spring is labelled as purple, and there is no red spring.

I am setting the sag as shown on the page below. Rider has some weight on pegs, and is sitting forward, almost to the gas tank. Maybe that is the trouble and he ought to sit back a bit.

Thanks for all the replies. Gives me lots to consider.

Edited by Eggbert, 14 May 2012 - 05:15 PM.

the color you are reading is the marking paint (a dab of paint on the spring which indicates its stiffness) and usually rubs off easily. the stock spring itself is red. get him to sit neutral on the bike (sorry about suggesting attack position as this is a far forward position) neutral basically means sitting in the middle of the seat with both feet on pegs (get someone to keep the bike balanced and not falling over as you do the measurements). what are your static sag measurements? get him to 100mm without telling him and get feedback. If he indeed is sitting too far forward during your measurements then maybe you are actually close as he sits more neutral on the bike (body position on bike can make quite the difference in measurements). is his weight 185lbs with or without gear? trust your manual and the guys on here when the say that 100mm is where you should be at. 85mm is going to make the bike unstable in the rough and break traction under hard acceleration. what is your riders level? beginner, novice, intermediate? what style of track are your guys on? (low speed with lots of jumps and rhythm sections "supercross", or long fast straights with rolling jumps and terrain "motocross") look forward to your reply...

Ahh... that explains the colour mystery. I'm sure it's the stock spring, as he's the 1st owner of the bike. And Yes, rider position may be the snafu here. We wern't sure, so he sat forward, up to the gas tank. I'll bet if he sits in a more trail-riding position, the sag will be a lot closer to 100mm. We'll test that tonight. Oh, and he was wearing his riding gear including helmet and boots for the sag adjustment. He's 185 in his shorts, so the gear adds some weight.

I recently set the sag for one of his friends who's light weight and rides a Honda 125 2-stroke. That worked out great, and from what i remember, the young lad did sit more in a trail riding poistion.

I'll have to check the static sag. It was pretty neglible when the spring was factory set and yielded only 70mm of race sag. There's undoubtedly more now.

I'll check static sag and re-positioned seat sag this evening and get back with the results.

He only started racing a few years ago, and last year switched from a RMZ250 to the 450 for the Fall season. That's MX Junior for 450 4-strokes and 250 2-strokes.

For just starting a few years ago, he's not bad, but he performs much better during practise than during a race. There's an intimidation factor as most of the other riders have many more years of experience. Anyway, the following video gives an idea of the type of tracks and his abilities, although as I mentioned, he's much more impressive when he's relaxed on a practise track (which is likely the reason for his arm pump).


He's number 427, and this must be on his 250, as it's from 2010:

Edited by Eggbert, 15 May 2012 - 05:15 AM.

i myself have only started racing about 4 years ago so i know where he's coming from, since i have a job i dont go nuts at the races but i do decent. if i can make an observation from your video, he looks a little stiff on the bike (not moving around) and is sitting a lot. i think that sitting is fine if the track is smooth enough but the purists will say that the only time you should be sitting is at the appex and out of a turn. otherwise for starting so late he doesnt look bad, seems to carry momentum well, will justy have to get more saddle time to get those nerves under control.

back to the suspension, gear will add about 15 to 20lbs to the rider weight (so about 205lbs for spencer) which may indicate the need for stiffer springs. regardless, getting him to sit in a more neutral position (much like in the video) should yield a good sag measurment.

Yes, he does sit too much, although he knows that and is working on it. He has improved since the video was made. He rode Beginner in 2009, MX Junior 250 in 2010, switched to MX Junior 450 half way through 2011, and wil be racing in the 450 class again this year.

He likes the 450 as he does a lot of fun woods running and gravel pit stuff with his friends and likes the extra torque and power of the 450. Based on MX racing, he likely does better with the 250. I like to see him in the 450 class as he's usually racing against only 15 riders or so.  When he was racing 250's, there was usually about 36 to 38 riders, and I never liked watching the start. After about a 1/2 lap or so, things start to thin out and I'm comfortable watching.

We checked tonight and when he sits around the middle of the seat, (a typical trail riding position), I get 90mm sag, which is closer to the recommended 105mm. From this, I know the adjustment for 105mm sag will not be nearly as soft as when I adjusted it before (rider sitting near fuel tank). So that seems to be most of the problem. The rest is likely him not being used to it.

The static sag surprised me. 35mm static. The 90mm we are presently adjusted for, is made up of this 35mm plus another 55mm once the rider climbs on board.

Thanks for all the replies. I appreciate them.

Edited by Eggbert, 16 May 2012 - 01:52 PM.

your static sag is about right (but this measurement is somewhat unreliable due to binding of the shock linkage/bearing) some get an average measurement by first lifting the rear of the bike and letting it drop slowly and take a first measurement. Then they will compress the shock and slowly let it release for the second measurement. averaging the two values is supposed to yield a more accurate static sag measurement. irregardless the more important measurement is your race sag, you dont have to go all the way to 105mm, you can try 95mm and see if that's the best compromise for him. (im of course assuming the measurements are being made with him in full gear). once the sag is setup up, it will be time to play with the clickers and fork height.

i can relate to the 250 class, my last race had 36 riders on the gate in my class alone (250B), 450B had 19. its not too bad on the track, the starts also intimidate me and i always let them go since i cant afford to get hurt and miss work. however the 250 will teach you to keep your momentum going. i am going to consider moving to the 450 class myself either next year or a the year after.