Ask Pinkbike - Crank Woes, Coil vs Air Shock, and Which Nukeproof?

Oct 7, 2014
by Pinkbike Staff  
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Here at Pinkbike we get inundated with all kinds of questions, ranging from the basic "Can I have stickers" to more in-depth, soul searching types of queries like if you should pop the question or what to name your first child. Ask Pinkbike is an occasional column where we'll be hand picking and answering questions that have been keeping readers up at night, although we'll likely steer clear of those last two and keep it more tech oriented.



Crank Grief

Question: Pinkbike user wrovmtb asked this question in the Downhill Forum: I have a 2012 Mongoose Fireball that I use for 4X racing, but the bike's non-drive side crank comes loose every time that I ride it. The guys at the bike shop said that the cranks, Duros from Suntour, are worn out and that I should replace them, but I can't find any good Octalink cranks... should I buy a new bottom bracket as well? And if so, what type?


bigquotesThe short of it is that the bike shop is correct when they told you that your cranks are worn out, and that you'll have to replace at least the non-drive side crank at a bare minimum, although it'll be like winning the lottery if you manage to track down a shop that has a spare non-drive side crank in their parts bin. The mountain bike version of the old Octalink bottom bracket uses a steel spindle with eight splines that are each 9mm long, and the matching aluminum crankset sports the opposite shape that mates to it when the arm is pressed onto the spindle as you tighten the crank bolt. The issue boils down to this: the spindle is steel, the arms are aluminum, and you accidentally rode the bike with the crank bolt a touch loose. The non-drive side arm lost the battle because aluminum is way softer then steel, and the result is a deformed shape to the mating surface that means the arm will never stay tight for long again. The thrifty route would be to track down a new or used Octalink crankset, but I'd take this ''opportunity'' to upgrade to something else, like Zee cranks from Shimano or Gravity's Gap Mega Exo arms that go for around $200 USD. - Mike Levy

Shimano Zee DH Crankset 2013

Shimano's Zee crankset is a worthy upgrade if wrovmtb isn't lucky enough to track down some replace Octalink compatible arms.



Coil or Air Springs for Enduro?

Question: Hecop wrote: in the All-Mountain and Cross-Country Forum: I want to change my Fox Float CTD shock to a Cane Creek Double Barrel coil for my Intense Tracer 2. They have the correct coil shock for my bike's travel, but I don't know if this change will benefit my bike's response going downhill. Is a coil shock better than an air shock for an enduro bike?

bigquotesThe simple answer is "yes." A coil-sprung shock with both high and low-speed damping controls will be your best option for downhill performance. The advantage that a coil spring has over an air-sprung shock is mainly in the first 30-percent of the suspension travel where a coil offers a smooth, linear rate and an air-spring is making the transition from the effects of its negative spring. The difference is small, but most good riders can feel it. There are valid arguments in both camps about the benefits of coil vs air springs in the last 25-percent of the suspension's travel, because the air spring naturally ramps up, while the coil type shocks must depend upon a rising-rate linkage or an end-stroke booster to achieve the same effect. If one checks out the Rampage bikes, the end-stroke winner appears to be the air spring, but I digress. That said, it's the first half of the suspension travel that provides traction and control, which is where coils rule and why DH racers use them.

Where coil shocks disappoint is in their versatility. (negative commenter warning: you may want to read a little further here.) An air spring with high and low-speed damping controls can be firmed up for park riding, softened for loose, gravelly descents, or set up as a compromise between good pedaling for trail use while banking enough DH performance to enjoy the downs. All from the same shock. Coil springs are one-shot deals. You must select one spring rate that suits the style of riding that you like most and then live with the compromise should the terrain or trail require a different setup. Cranking up the preload won't stiffen the spring - it just makes low-speed hits harsher and reduces sag. So, to answer your second question: "No." A coil-type shock is not the best choice for enduro. An air-sprung shock like the Cane Creek DB Air is a better solution for a bike that must be ridden fast and hard in a wide variety of terrain and trail situations. If one considers that most of the top enduro racers have histories as pro DH racers, the fact that almost all of them choose air-sprung shocks should be evidence enough. - RC

cane creek double barrel shock details

If you race DH or ride the same type of trails every day, a coil-type shock (pictured) will deliver the best performance on the downhills. Those who need a shock that can be tuned for a wider variety of situations and still want to rip the downs, should choose an air-sprung shock with a full range of damping adjustments like the Cane Creek DB Air





Nukeproof Mega AM or TR?

Question: PB user Giladgu asks the following in the All Mountain, Enduro & Cross-Country forum: Hey PB, I was looking at both the Nukeproof Mega AM and TR as a new frame but can't decide if I need the 160mm travel on the AM (I will be running a 160mm fork on both). I ride mostly trails in the Northeast (NY and NJ) and once or twice a year at Mountain Creek. I just don't know how much pedaling efficiency I lose with the AM. I am also thinking of maybe racing a bit this year and I'm kind of worried whether or not the 130mm of the TR would be able to handle some enduro events.

bigquotesThe number of bikes in the 160mm category continues to grow, but that doesn't mean that everyone needs to rush out and buy the longest travel bike they can find. To a certain extent, the terrain that you're riding most often should dictate the bike you buy, and in this case I'd recommend the TR version of the Mega. It shares the same link-driven single pivot suspension design of its burlier big brother, so the actual pedaling characteristics should be similar, but its lighter weight and reduced travel will help with the steep punchy climbs that the East Coast is filled with. It'll still be able to handle a few days in the bike park without much trouble, and the same goes for the occasional enduro race, especially since you're planning on running a longer travel fork up front. There are some bikes in the 130mm travel category that are more XC oriented, but the Mega TR isn't one of them, with geometry numbers that are geared towards aggressive riding as opposed to leisurely cruising down gravel roads, making it a good choice for your intended usage. - Mike Kazimer

Nukeproof Mega AM 275 review
The Nukeproof Mega AM is highly capable, but it may be more bike than PB user Giladgu needs.


Have some unresolved tech questions? Jump in the Pinkbike Forum and we'll look to answer it for next time.


101 Comments

  • 75 2
 Where's the lockout on my Fox 40?
  • 162 2
 Use a hammer to bend the stanchion, it will lock it.
  • 32 69
flag harrisonscottson89 (Oct 7, 2014 at 2:16) (Below Threshold)
 You just went full retard bro.
  • 44 7
 Never go full retard.
  • 45 2
 I just bought a downhill bike and was wondering if my Kmart helmet will work?
Also I set the tire pressure to 50 psi does that sound right?
  • 129 0
 Try setting tire pressure to 49 psi on the left and 51 on the right to compensate the weight of your drivetrain.
  • 21 0
 make sure the bolts on your linkage are tight, REALLY tight.
  • 50 0
 How hard should I hit the valve stem with my hammer to increase tire pressure?
  • 15 3
 How to fix any creaky component in two steps:

1. Tighten until threads just start to strip. Tighten 1/64 turn, no more.

2. Back off exactly 3/32 turn. This is the critical step!

Torque wrenches are a scam perpetuated by the tools industry!
  • 14 0
 Race plates add 32 horsepowers. Gold components add another 3 horsepowers each.
  • 7 9
 Torque wrench industry did not take into account the weight winnies and their alu bolts. Rhythm is a dancer.
  • 5 2
 @faul not everyone has acsess to the dual chamber tires with left and right man. That's a bit hardcore
  • 9 0
 I have this problem as well. I have a Fox 40 on my roadie and pedaling efficiency is garbage.
  • 24 1
 The choice between Shimano Zee or gravity gap cranks should be a no-brainer. Zee has a better interface with the bottom bracket (which is where 90% of crank failures are going to happen....as the initial problem to this response shows) and I'm pretty sure they are going to be lighter as well.
  • 6 0
 I bought the Zee too, and i am 100% satisfied with it. Good serviceability, stiff enough for my downhill use, and it was 107USD converted from my currency, here in Hungary. It is definitely a cheap and good solution. The biggest withdraw is the paint on the cranks, they strart to dissappear, but this should be the biggest problem.. Smile
  • 7 0
 To combat the paint problem, you can get crank decals off of slik graphics to protect or freshen up the crank
  • 7 0
 or just helitape/clear plastic coat the crank arms, OR buy SLX, if you're not a monster clydesdale then you won't notice the stiffness difference, and the polished arms don't scuff.
  • 7 11
flag MattGreenwood (Oct 7, 2014 at 2:10) (Below Threshold)
 @blitz66 i did, noticed the stifness from slx to xt (slx is marginally stiffer) and xt to zee (zee is way stiffer) and im not a "monster clydesdale" at 88kg and 5'9
  • 6 0
 Just in case the guy does accidentally track down a random/spare non-drive side Octalink crank arm (or a set), it should be pointed out that there are two versions of Octalink, V-1 and V-2. For Shimano cranks the V-1 fits XTR, and road cranks from Tiagra level and up. The V-2 fits mtb cranks from XT on down, and road cranks starting at Sora level and down. Non Shimano Octalink compatible cranks will be V-2.
  • 9 0
 fair enough @MattGreenwood the SLX isn't as stiff as Zee, but it's barely noticeable, and coming from almost any octalink the new SLX will be a significant upgrade in stiffness, not to mention disgustingly light as well
  • 2 0
 Zee is also cheaper than slx
  • 6 2
 Hell Deore Hollowtech 2 cranks will be a step up from the Suntour Duros, but I like how its an "opportunity" to spend $200 instead of $25 for a replacement crank arm.
  • 3 0
 i have been running $100msrp deore's since 2009. Replaced the bb once, and everything is all good still. Holding up better than my truvativ holzfeller oct's somehow.
  • 1 0
 @Martynich94 its too late Big Grin the left is bare metal at some places, now im thinking to take it to a friend and sandblow the colout of it, and use as "metal coloured" it should be nice too.. Smile
  • 2 0
 Thanks for the advice!
  • 2 1
 Zee and slx are the same crank with different options.
  • 4 1
 Zee and old deore you mean...
  • 2 0
 Shimano now offers the hollowtech 2 option down to the Alivio group level, and they're plenty stiff enough for 4x racing.
  • 1 0
 They also don't look that bad. The silver finish looks great in person.
  • 3 6
 Alivio cranks definitely look nicer and ironically seem more expensive than latest XTR, which lands somewhere among touring offerings from Suntour
  • 17 0
 Plus gravity gap cranks weigh about 400kg.
  • 17 1
 To the Northeast guy, get the 160mm bike. Its all rocks and more rocks.
  • 2 0
 This.
  • 4 0
 i owned both loved the 26" AM and never really got along with the 26" TR
  • 3 0
 From an East Coast guy who rode and knows all the trails you probably do... Go with the bigger bike. I'm sure the 130 is capable. But with all the big rock features, drops, rollers, etc., you need the travel in the rear. Not to mention that Mountain Creek will chew up the TR and spit it out after one day of runs. I know... I rode my Trek Remedy there for one day and it wasn't pretty.
  • 11 0
 RC - When are you going to do another one of those articles where you feature a bike from the 90s? I saw a guy riding a Nishiki Alien at the grocery store the other day. You could still make our your signature on the (elevated) chainstay.
  • 3 0
 Dirt Rag does that every issue.
  • 3 0
 I'm not even a good rider and I can feel the negative transition in the first 10mm of my dbair.... If it wasn't so damn light and so much more adjustable than the stage 5 it replaced, I wouldn't have bothered. .. oh, and the 300 bucks extra for an rcs ti spring didn't help the elka's fate either
  • 4 1
 I also had to chose between the Mega AM and TR, I took the TR and would do it again. Perfect for enduro and even with just a 1x9 Drivetrain with a 36 tooth chainring and a 32 tooth cassette it climbs the steepest trails. I also took it to a race of the German Downhill Cup as my second bike next to my Big Bike, but then I rode the whole weekend on the Mega and archieved a better result than I thought ;D
  • 2 0
 I have the Mega TR. And absolutely love it! Really challenges me to go faster as a rider and soaks up everything i throw at it pretty much! Perfect for trail centres and kills it in the air too... The only time I've struggled with the lesser amount of rear travel was when I took it to NZ last year, when riding Queenstown bp the blacks got pretty intense, and when the trail had been super chewed up with braking bumps. But to be honest that would be the case on many a bike. TR all the way.
  • 1 0
 Regarding the nukepoof megas
I own both, well i have an am 275 & the 26" TR & race enduro in the UK on both
The AM275 has 160mm Pikes & the 26" TR has 160mm 2015 fox 36's

There is a big difference in the ride between these bikes in that the 275AM seems to effortlessly barrell through and smooth out everything, where the TR feels fun and playful, but like a hard tail when things get rough.
I have raced enduro on both & all my best results have come on the 26" TR, but this is in the UK where the courses are quite pedally and not very rough. I have also ridden DH tracks on the TR and it surprised me how quick i could go to. If i could only keep one it would be the TR as it is more fun to ride.
  • 1 0
 Having ridden most of the Northeast, I would go with the AM. The area that he rides (especiallly north NJ - Jungle, Wayway, Ringwood, Mooch), has very little flow, and relentess rocks. I have yet to meet anyone who laments having too much travel. Sure 5" is good, but 6" is better if you have the choice. I think that the MC Bike Park may be one of the few places he finds flow. I'm also guessing that he is relatively new, since if you've ridden the area it would not even be a question, you would know what you want.
  • 1 0
 ^^^THIS^^^ ...regarding bike selection.

SlowdownU, there actually are quite a few spots across the river in Westchester, NY (Sprain, Graham, Blue Mountain, etc., etc.) that have more flow than I've found most other places, particularly in the South West, where I now (regrettably) reside.

Just in case you're in the area again... you gotta check the aforementioned spots.
  • 1 2
 So you dont have to read all the stuff below this comment when you preload the spring you push the piston (the shock part not the spring) up extending it all the way. So when you sit on your bike the spring and piston still move but they go back to the original position they started at before you preloaded they spring. I'm only thirteen but this seems way simpler then all the stuff below this. Anyway who cares what the shock does as long as you can shred on it its golden
  • 1 0
 Dear RC.

regarding coil vs.air: I am still trying to wrap my head around something. maybe you can clarify that for me

You state that one advantage of coil is that they don't ramp up

a little further down you state: You can change the sag with the preload on a coil spring.

So a linear Spring rate basically means you need X amount of force, or weight to keep it simple, to compress a spring for a certain distance. for example 400pound per inch is a very common rate. So if you sit on your bike, depending on the links and leverage ratio your bike sinks in because you apply a force or weight to the spring, right? lets say you are 200 pounds and your frame has a 1:2 ratio. this meas you end up with 1inch of sag. correct?

If you now preload your "linear spring" lets say with 100 pounds the spring changes its length. The spring on the shock will be a quarter inch shorter the shock length stays the same though as does frame and suspension geo.
So if you throw your 200 pounds back on your bike now, remember the 1:2 ratio this means 400 pounds on the spring.
As its a linear that means it will sink one inch further into the travel and your bike will be exactly the same as before.
even if you would but 10.000 pounds on the spring before adding 400 to a linear spring with a spring ratio of 400pounds per inch means its length will be compressed for another inch, no matter ho much weight or force you put on before.

So dear RC you can choose now from two answers: 1) a coilspring is not really linear either
2) you can not control sag with spring preload.

what do you think is the right answer?
  • 2 1
 My first reaction is that this is an oversimplified argument. Preload gets the shock into hypothetical "negative travel" (I don't know what else to call it) where there is spring compression but the shock cannot move. For example, if the coil is at exactly zero preload and the shock fully extended no sag or spring compression exist. For an example of my theoretical negative travel, we will use an extreme amount of preload: a number of turns equal to 1" of shock shaft travel. The shock cannot extend anymore because it is topped out, but in theory it would extend 1" if it could. When you add the 200# rider, the shock will return to the zero shaft load position without actually moving. It will still be topped out, but without load against the top-out bumper. All the rider's weight has done is "undo" the theoretical negative travel that existed and return the shock to an unloaded state at full extension.
-This all assumes you have a bike with a 1:2 ratio that is exactly fixed somehow.
-The error in the above is that adding preload is a different vector than adding weight to the bike.
-I currently believe that both statements in the OP are correct unless someone can change my mind. A linear wound coil is linear. Increasing preload will decrease sag.
  • 2 0
 Check out this PDF:
www.sram.com/service/rockshox/443

Page 5 has a spring rate graph
Page 7 Shows how preload affects the shock
Page 9 Shows an air spring curve
page 11 show the difference with air pressures vs volumes
page 12-13 talks about negative spring

Hope this helps!
  • 1 0
 Nice link! To be read during a quiet spell at work. Consider this preload example:

Wind on preload equal to your weight (let's ignore frame ratio, front suspension taking some of your weight etc) The coil is compressed but not the shock. Now get on the bike. The coil is compressed between the preload collar and your weight on the end of the piston, ie it is compressed just the same as before, and the shock doesn't compress. So, preload does control sag.

Or look at it another way. No preload. Get on bike. Shock compresses. Winding on preload uncompresses shock.
  • 1 0
 Terryotomy
You are right it is simplified. but still hard enough to understand i guess.
Whenever RC is writing about tech stuff i get the shivers. Apparently he must taken physics classes at Pokemon university or something similar... I would like to give it some time see if RC might give us honor before coming back to your points but whatever...

-you are wrong. if you preload a number of turns equal to 1" of travel an than ad 200 pounds cause by a rider. Your resulting weight (actually its a force) compressing the spring is your 400lbs spring is 400lbs through preload+plus rider= 600lbs which will result in 1.5" of total spring deformation considering its linear or in other words in 0.5 inches of sag measured on the sock. however you twist an turn it, with linear you will always come to the same result.

-you are right it will change the properties in negative travel, a higher preload will cause the rebound to get faster as a higher force is pushing the shock back in its extended position. more force means higher acceleration means moving faster by the time you top out.
-you are right, the ratio is not fixed as long as you have a rear moving on a circular bearing. RC actually states that correctly. it does not however influence the sag as when you only preload the length of the shock does not change but stays at fully extended length. meaning your linkage will start moving from the same position hence same ratios will apply as without preload an can therefore be taken out of the equation.
-nope, the force vectors are the same. your shock is designed to accept only one direction along it longitudinal axis.
- correct both statements are well lets say not exact...but then again i just repeat what RC wrote...
  • 2 0
 Michibretz: if you have 400lbs of preload, and 200lbs from the rider's input, the schock won't move because you need to overcome the preload.
400lbs of preload = the spring is already "pushing" 400Lbs when the shock is fully extend.
  • 2 0
 You all should check out page 7in the link above, the graph explains this very well.
  • 1 1
 hell why would the shock not move? if you have a spring long enough and you put a weight on top of it it will be compressed. lets say 400lb deform the spring for and inch. a fact that we can all agree on right?

if you now put even more weight on it it will compress further? right? 200lbs extra will press the spring down another 0.5inch to 1.5 inch total.. its called hooks law.

You are saying it only starts moving again if you put on more than the wight you put on at first?

check out the preload graphic on page 5 of the rock-shocks document crazbiker4 shared.

no mater if you take the light blue or the dark blue line as soon as you ad 200lbs this translates in 1" of travel at their 200lbs spring ratio.

now the difference is that the spring contains more energy which while significantly change the way the spring pushes the shock back into its extended position.
Imagine your spring with the 600 lbs on top. release the spring from the weight and it will take of like a rocket. With only 200 lbs it will probably take of too but will not fly as high... its like slingshot the harder you pull the further it shoots or coming back the harder your bike will kick back and the higher your bunny-hops will be...
  • 4 0
 There is a 100lbs preload on the graphic on page 7. If you put less than 100 lbs, it won't move.

When you preload a sprig with 400lbs, the spring is pushing 400lbs. It can't take his initial lengh because of the schock body taking 400 lbs of the preload when in top out position. If you put 200lbs from the rider, the shock will still push 400lbs, but there will only remain 200lbs in the shock body. but the shock won't move before the rider input is over 400lbs. If the rider put 800lbs, there is no more lbs in the shock body, and the shock has move. The shock has move 1 inch from his initial position, but the spring itself has moved 2 inches: 1inch from preload and 1 inch from schock movement.

I hope someone will understand what I just wrote.
  • 2 1
 The key thing to realise is that the preload collar only compresses the coil if the other end of the coil is fixed, ie the shock is fully extended. Once you get on the bike and compress the coil and shock, the preload collar doesn't add to the coil's compression, it just moves the whole coil and so extends the shock and alters the sag.
  • 1 1
 that's the point @lochussie
  • 2 1
 @michibretz The simpliest way to clear your doubts is to state that "linear" does not have to mean a horisontal graph, you are talking about. If you immagine a graph presenting spring progression, a coil spring graph rises along a straight line, and an air spring rises along some parabolic shape. So if you have a 400lbs/inch coil spring, it stays 400 only without any preload. Applying preload the numer increases. All manuals state that there should be no more than two full rotations of preload, so I am guessing that this would be no more than 50lbs because there is 450lbs spring available. Here: linear means that one rotation would be equal to 25lbs/inch ADDED to your basic 400lbs/inch.

Adding preload increases the force, this way rebound damping should be increased as well. I use a 650lbs coil spring and high viscosity oil in damper, so my seals do not last too long. I preload the spring to have something around 660lbs/inch. Applying my immense weight on the spring with the right sag and some heavy landings, the oil pressure inside gets so high that I often change blown seals.
  • 1 0
 jedrzeja, i actually wanted to provoke a reaction from the author, RC, yes i admit i don't like the marketing text he posts... anyway it was fun with you guys too...
  • 1 0
 I should not be here anyway.
  • 1 1
 you've already read all the stuff above this but this is my opinion when you preload the spring you push the piston (the shock part not the spring) up extending it all the way. So when you sit on your bike the spring and piston still move but they go back to the original position they started at before you preloaded they spring. I'm only thirteen but this seems way simpler then all the stuff above this. Anyway who cares what the shock does as long as you can shred on it its golden
  • 3 0
 I have a better idea: go out to your garage and wind in sixteen turns of preload. Then get on your bike and see if it compresses. Then f*cking neg prop me.
  • 1 1
 @yetikid,
When you preload the spring it has absolutely no affect on the "piston". Your spring and preload is completely independent of the piston/dampening section of the shock and vice versa. The spring holds your weight, the piston and dampening affect the shaft speed while the shock is moving through it's travel. They work hand in hand but not even remotely like you're describing.
  • 1 0
 When I read your American "innocvtions", I am wondering how on Earth, you are still alive. Nothing prolongs under preload, even if it belongs to a thirteen year old enthusiast. Springs shortens and eye and eye stays constant unless a rider is on a bike.
  • 1 0
 Hope I am not too late. Maybe a little physic can help understand you what is going on with spring preload...

A spring exert a force according to that very first order and linear equation: F=k*d
F is the force (in Newtons)
d is the length the spring is compressed (in meters)
k is the spring constant in Newtons per meters (N/m). It is constant. It does not change according to the rain, the sun, the compression , the leverage or whatever else (except is it gets weaker as it gets older, just like us).

Any mass (pounds, kg), excert a force down toward the ground that is measured in Newtons also. So, your body weight exert a force in Newton down toward the ground. Invertly, a force in Newtons can be expressed in pounds. We will allow us to use Newtons and pounds alltogether to simplfy the explanation.


The force excerted by the spring basically fights against the rider's weight. When two forces are equal, there is no movement in any direction.

If you turn-in the preload collar, you compress the spring which respond by forcing the shock to uncompress. You are not on the bike yet but the shock is already trying to uncompress the shock. Eye-to-eye distance of your shock cannot stretch any longer and the shock sustain that force.

Now you sit on your bike. The force you exert on the seat-frame-linkage-shock must first counteract the force exerted by the preloaded shock. If the spring is preloaded to 100lbs, the first 100lbs applied to the spring will generate no displacement (no compression). Every other ounces will compress the spring/shock.

That is how preload allows you to set the sag.


Now, go out and ride!
  • 1 1
 Way too late and the answer was given in a correct and very short way further up in n easy 3 sentences... thanks anyway this was an experiment gone wrong... thread closed
  • 1 0
 If you're excited about enduro, definitely go with the AM. I rode my AM at the Plattekill enduro and appreciated every mm of that rear shock. It also rode great in a downhill race at Blue Mountain. You can enjoy the AM on single track, but I'm not sure the same would be true of the TR on the enduro courses I've seen in the northeast.
  • 4 0
 Pretty disappointed that ccdb air cs/inline can't fit my slash8 2015
  • 1 0
 RC, perfect response to the Air vs. Spring shock question. I am looking to get an air shock so I can change the sag quickly depending on what I am riding for the day. Same goes for the fork as well!
  • 1 0
 This always confuses the heck out of me. I realize you cannot change the spring rate of a coil shock without changing springs, but you can still dial in the desired sag with the coil spring without changing springs. Does this imply that changing air pressures on an air shock also changes its spring rate, while at the same time varying suspension sag?
  • 2 0
 Yes..... The springs job is to support the riders weight. Think of it the same as a car tire, if you put 15psi in it then it looks like its sagging low and its soft, if you put 32psi in it then is looks “right”, but its harder. This is the same thing as an air spring. Say for example you are going to rip at the bike park all day, you want your sus to be more plush to give you the traction and soak up the small stuff then you can lower your air to the recommended sag %. If you are going to ride trails then you may want the sus to not bob as much for pedaling efficiency, so you set the sag a little higher. Remember, you want to be able to use most of the travel so you would only be switching back between 20-35% sag if you go more either way then the bike will most likely bottom or bounce the crap out of you. There is other adjustments that help… high/low speed dampening. For example if you want to run 25% sag all the time but want the suspension a little more plush then you could run less compression so the shock is not slowed down too much. Or if you know when you are going to pedal for a while you can ramp up the low speed compression to keep the bike from bouncing during pedal strokes. Or if you have a shock with a climb switch, lock out, CTD ect… then that is the same thing as adjusting the compression settings but with the flick of a switch on the fly. I think a climb switch is the way to go these day for anyone trail riding most of the time.
  • 1 0
 If you want to use a coil shock then you will need to most likely switch out a spring if you want to go from 20% to 35% sag. On my bottle rocket I can run a 450lb spring or a 500lb spring, however when using the 450lb spring I need to max out the preload to get the sag right. If I use the 500lb spring then I do not need to preload the spring at all and can just adjust the dampening from there. Maxing the preload changes the feel of the shock in the top end, so I like to get as close to what is needed for my weight. Like RC said if you are doing the same thing over and over again then you a spring shock will work really well.
  • 3 0
 Check out this PDF:
www.sram.com/service/rockshox/443

Page 5 has a spring rate graph
Page 7 Shows how preload affects the shock
Page 9 Shows an air spring curve
page 11 show the difference with air pressures vs volumes
page 12-13 talks about negative spring

Hope this helps!
  • 1 0
 Sweet, thanks a bunch for the input and info crazbiker4! One follow up question to your coil spring comment, and using your example as a reference: if you are at the borderline of say, a 450lb and 500lb spring, theoretically you should be able to get a decent sag range without having to resort to maxing out preload on the shock. So is the key to get spring weights that would get you at 20% and 35% sag without having to introduce much preload?
  • 1 0
 No problem... You can do either because it may be a personal preference. Refer to page 7 in the PDF.... In the graph you can see when the purple line is a higher spring rate then the blue line both start at 0lbs force. When you add preload (light blue line) you can see that the amount of force to compress the spring 1in is higer then the blue line but does not ramp up like 300lb spring. That preload force has to over come before the spring will compress. IMO, this may help pedaling but will beat you up on the small bumps. Not too mention if you take a big hit you may have your compression set to allow the shock to feel more plush but its not able to slow you down enough to keep you from bottoming out. So thats why I would go with the highest spring rate that I can to achieve the closest to my sag. On fox spring shocks you can only turn the preload adjuster 3 full turns before they say to go up one. So in the example they are preloading the spring an inch which you will never do that on a MTB. This goes back to why I think air is better because you can set it up for 25% one day for park riding and then 15% another day when trail riding. Just verify with the frame MFG on what the rec sag is for that bike.

If you are running a coil and want to check your spring rate, here is a calc to help you:
service.foxracingshox.com/consumers/index.htm
  • 1 0
 Thanks a bunch again! That really made sense. And those links are incredibly useful.
  • 4 1
 Pinkbike is correct, the Mega TR is more versatile than the AM. I have owned both.
  • 1 1
 Air vs coil: as much as there's more configurability with an air shock, if they weighed the same as a coil shock I would imagine the majority of EWS racers would be on coil?

It's the 3-400g weight benefit which I think is more significant than air offering better performance in differing conditions
  • 2 0
 I was planning on fitting a db inline to a slash 9.8 2015. Why don't they fit? No pripority shock hardwear anymore.
  • 2 0
 why are there so many crank/bb combos.. I can't even figure which ones to buy for my kona process... its mind numbing..
  • 2 0
 A shimano BB and pretty much any decent crank, except the new raceface cinch cranks, will work fine. I run a set of atlas fr on my 153.
  • 1 0
 really that easy?? do the bb30 ones fit? what is the spacing?
  • 1 0
 Found this yesterday when trying to find out which BB brands I could use with some gravity moto X cranks: wheelsmfg.com/complete-crankset-bb-adapter-guide

Should help you out.
  • 2 0
 @billybobzia - There are 3 major spindle standards - 24mm (Race Face EXI & X-Type, all Shimano and most FSA), GXP (Only Used by SRAM/Truvativ) and 30mm (Race Face CINCH cranks, SRAM/Truvativ BB30 FSA/Gravity BB30). Your Process has the BB92 BB standard, so just pick the BB92 for the spindle standard you want to run and you're set. Just remember if you get a GXP BB, then you can ONLY run SRAM/Truvativ GXP cranks.

Personally, I'd just go for any of Race Face's CINCH cranks and CINCH BB. The cranks have removable spiders and removable 30mm spindles, so they're essentially future proof. If you change frames or drivetrains, you can just swap out spider or spindle and you don't have to change your cranks (www.raceface.com/cinch).
  • 2 0
 If you end up rounding your non drive crank a bit you can still fix with epoxy resin and ground metal powder
  • 2 3
 Shitty MTB junk. f*ck the POS MTB crank & get a BMX crank, splined & pinched on both sides & you won't have a problem. The BMX industry figured out a long time ago how to do things right that the idiots in the MTB industry still seem to not know how to do. Either that or they engineer junk on purpose just to keep selling replacements.
  • 1 0
 I can't figure aluminum cranks, especially aluminum threaded inserts. They suck! Not worth the weight reduction if you want your bike to last.
  • 1 0
 I have a question about MegaTR to anybody who own one and rode it in harder than UK environment. Would you take one to Mega Avalanche and ride it?
  • 2 0
 Id go for coil with 3 different springs for different terrain
  • 1 0
 This 40 is pretty much locked for obvious reasons www.pinkbike.com/photo/10504239
  • 1 1
 is 300 psi in my shock enough to keep me from maxing out on a one foot drop? (:
  • 2 1
 Vivid air r2c for dh?
  • 1 2
 I'd go for the MEGA AM, more travel, more versatility.
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