Ask PB: Zero-Extension Stems and Air vs. Coil Suspension

Jun 9, 2015
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.




Zero-Extension Stems

Question: Edfire asks in All Mountain & Cross Country Forum : I'm currently riding a Specialized Enduro Pro, and Im wondering: I'd really love my bars a couple centimeters back from where they currently are, and I'd like to know if is it possible or feasible to have your bars directly over your forks? (Rock Shox Lyrik) And if so; are there any reasonably affordable ones around?


bigquotesI spent a day riding with Fabien Barel in the French Alps when he was designing bikes for Mondraker. He had just released his "Forward Geometry" concept with its super-extended top tube, short chainstays and a special, ten-millimeter stem. The concept, which has recently become the vanguard of enduro-inspired fashion, was proven by Mondraker's Summum DH bike, which featured similar geometry and a zero-extension direct-mount "stem" on its dual-crown fork. Mondraker's team did well aboard the Summum, and it remains in production. When asked why he stopped ten millimeters short of a zero-extension stem for Mondraker's all-mountain Foxy and Dune models, Barel said that the zero-extension stem made the bikes steer and handle unpredictably. He then mentioned that after testing a number of extensions, from negative ten through thirty degrees, he found that ten degrees was the shortest he could use while retaining the steering precision and stability which he believes are the key elements of Mondraker's Forward Geometry designs. Mondraker has since updated the Summum with longer stems, ranging from ten to 30millimeters, presumably for the same reasons.

At least three makers offer zero to ten millimeter reach stems that fit standard steerers. all clamp over the top of the fork's steerer tube, with the OEM Mondraker Onoff Stoic 10mm stem being the best looking of the lot. The Mondraker stem is priced around 89.95 Pounds in the UK, and is available at Mondraker dealers. PDent is another option. Designed by inventor Kirk Pacenti, the founder of the 27.5-inch wheel movement, PDent is a handlebar and stem system that clamps the bar in the conventional way, and achieves stems as short as 25 and 15 millimeters by denting the center of the handlebar, so that the fork steerer and bar can occupy the same space. Pdent is going to be pricey, because you will be purchasing a bar and a stem, but it solves the short stem equation without adding unnecessary height to the handlebar. - RC
Emmeline Ragot s Mondraker Summum pro team bike. Her bike frame is thus far a stock frame there have been no shortcuts on tubing or custom geometry tweaks. Mondraker does put a special custom paint job on each of the team bikes for MS-Monderaker.
Emmeline Ragot's Mondraker Summum team bike.

Onoff stem
Onoff's Stoic 10mm extension stem was designed for Mondraker Forward Geometry trailbikes.

Mondraker Dune Photo by Colin Meagher
Mondraker's Dune performed very well during Pinkbike's Sedona test sessions, surprising us with its technical climbing skills.




Air vs. Coil Suspension

Question: leibbi asks in the All Mountain, Enduro & Cross-Country forum:I have a 2013 Specialized Enduro EVO and my fork is giving me hard times. Can I change the coil fork out for a air fork and will it be OK for the performance and handling or will I ruin the handling of the bike ?
bigquotesYes, you can swap out the coil sprung fork for an air air sprung fork without any issues, and as a bonus you'll likely save some weight as well. You'll want to make sure you install something with a similar amount of travel or risk altering the bike's geometry enough to affect the handling, but otherwise there should be no problems with the proposed switch. Coil sprung forks are often praised for their superior small bump sensitivity, but the last few years have seen the performance difference between air and coil become negligible, and the fact that an air spring is easier to fine tune to a rider's weight makes it a better choice in most cases. If you need further convincing, take a look at the bikes of the top World Cup DH or Enduro World Series racers you'll see a number of them using air sprung forks matched with coil sprung rear shocks. - Mike Kazimer

Specialized Enduro Expert EVO
The 2013 Enduro EVO came with a coil sprung fork up front, but switching to an air sprung option shouldn't affect the handling at all.



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


89 Comments

  • 48 3
 Those stems just look odd to me...
  • 37 1
 PB standard response: the shorter the better for stems, just make sure your bars are at least 800 mm.
  • 7 0
 I had Vector expert bars on my BMX race bike in the late 80's. They had a quill stem but the bars were welded right to the quill giving 0mm reach. there was a slight angle to keep the bars rising vertical. They had about a six inch rise. They were definitely lighter than a bar-stem combo, but they also handled strangely. Much like if the front tire was skipping along the ground and never really digging into the turns. Like most trends and innovations in mountain biking, there comes a point of diminishing returns.


"http://bmxmuseum.com/forsale/9806"
  • 1 0
 @ChampionP I hear you. A zero reach stem is a bad idea, no matter ow you look at it, especially for a BMX. The deal is, the tires on bicycles are not that heavy and the momentum they keep is not that high, causing a lot of bump translation to the handlebar. As you said, the feeling that the tire is actually not touching the ground sounds like a perfect explanation.
XC has longer stems for control because of, you know Smile DH has shorter fr quicker turning and better response, but there is a limit.
  • 6 1
 I've got one of the 10mm stems on my Foxy XR, and while it does look a bit odd when you are side on to the bike once you are on and riding it...
a) I doesn't look crap at all from that angle.
b) Makes the handling awesome with the 800 wide bars (once you are used to just how much leverage you have!).
c) Just ignore the haters as you whip off into the singletrack!
  • 6 1
 at some point won't lots of people wish they had more reach adjustability than 0 to 30 mm?

that's part of the reason modern geometry is desirable -- with 80-40 mil stems you can actually fit the bike to your weird body. I somehow doubt that a few frame sizes can account for all the bio mechanical differences from person without being able to adjust reach and stack with stems and spacers. but since even this is an imperfect pseudo-science...I hope I'm wrong. I'm no sports scientist...just a bike rider.

with bikes like the summum...you have one shot at making the fit correct and buying the appropriate size...can't shorten the freaking top tube.

we can't all afford to make these sorts of mistakes---however a pro rider like Ragot gets a fit and a new frame if need be. doesn't have to worry about the grand or so they just wasted.
  • 18 0
 Here's a better 0mm stem design.
Also sporting some super short chainstays!

i.imgur.com/okIJr2j.jpg
  • 5 2
 This does depend a bit on where you are at in your riding style, but the general rule is that the stem is a bike handling device and not a bike fit device.
  • 2 2
 Well... just from my own practical experience, a stem does have a huge effect on bike fit....and my handling changes from bike to bike, accommodating that particular stem, within reason of course.
  • 3 1
 Also depends on the bike and the style of riding.
  • 4 0
 Pinkbike standard stem comment: put 800mm bars and the shortest stem possible on whatever bike you got.

Even if it's an XC/Trail rig and you're not descending like a madman. Even if it's a trIAls bike (oh the comments on Lenosky's bike post!)

Even if the reach is too short because most bikes are too short.

Even if the person has narrow shoulders.


*sigh*


It's the equivalent of roadies saying slam that stem.

While there's a reason it's popular and there is value in it for many, the gross generalization needs to stop because there are many riders (or rider/bike combinations) where it's a bad idea. There is no one size/approach fits all when it comes to bike fit.
  • 1 0
 Well, im going to try a 20mm first i reckon, seeing as how the RSP stem im currently on is 50...
  • 3 0
 @dontcoast It's a common complaint because bikes are still coming off the showroom floor with 80mm stems & ~700mm bars. most riders will have a better experience with bars wider than that, & if you specc something wider, it can be trimmed later, but you can't make bars that are too short longer.
  • 4 1
 I did make the disclaimer about riding style. Most XC guys feel comfortable locking their shoulders and elbows trying to consentrate on making perfect circles... so yeah, long stem narrow bars makes sense for that riding style, because they are actually turning the bars and not leaning. They "need" the stability of a longer stem.

I personally run an 805mm/40mm bar stem combo and a dropper on my XC hardtail single speed. Every corner I go into is with my seat dropped, leaning my bike, steering with my hips, ripping it as hard as I can. Seeing as PB is a more DH/Enduro specific site, they are typically spot on with recommending wider bars/shorter stem on bikes to open up the potential for this riding style.
  • 3 0
 Well...most of the top xc riders I've seen are very fluid and still lean a bike. They hit jumps, rock gardens and turns at speeds that many would be scared to ride on their 160mil trail bikes. They might lock their shoulders and elbows sometimes, but usually use their arms to absorb shock. A bar can be too wide, a stem too short, a combination thereof terrible or excellent for an intended purpose.

So I just try to stay away from predefining what I will do, because so many things change all the time. I mainly want to be comfortable cos I ride a fair bit. @Thustlewhumber 's 805/40mm combo might be perfect on another bike, but not my current trail bike and trails. Cheers!
  • 28 0
 Way to throw Pacenti under the bus! lol

("the founder of the 27.5-inch wheel movement")
  • 25 1
 If you keep up on maintenance for Fox 180 Van should feel like butter all day every day. I just had mine serviced and it's amazing.
  • 49 1
 "If you keep up on maintenance"

This is something people often forget. Don't run your shit in to the ground and then complain it doesn't work people!
  • 9 1
 It's just like buying a brand new car, not putting any gas in it and then complaining it doesn't want to go forward...... Some people, I tell you man!
  • 60 1
 I just bought a brand new bike and put gas in it and it still wouldn't go faster on the uphills. Felt heavy too.
  • 11 37
flag rigodon777 (Jun 9, 2015 at 21:57) (Below Threshold)
 And is your dick stuck in a toaster too?
  • 8 2
 @grgsmith: I think you put in the wrong type of fuel. Make sure you put in UNLEADED fuel and not Diesel.
That could be your problem.
  • 4 0
 @GOGRANDE How often do you have to do oil changes and servicing? I have a Marzocchi 55 RC3 and barely ever have to change the oil, its very reliable. I've heard stuff about fox maintenance and their crazy intervals on the manual, but how often do you really have to service them?
  • 6 0
 Also not addressed in the article: get the right spring for your weight. If the fork is "giving you hard times" there's a good chance it isn't set up right for you. A coil fork with a too light or too heavy spring is going to feel terrible. (Well, too light might feel great until that first drop...) The correct spring should feel amazing. It's also much cheaper to try a few different springs before shelling out $1000 on a new air sprung fork for the Evo.
  • 1 0
 @Revanchist it really depends on what you ride and how much. I crush the parks all summer and ride aggressively. I try to aim to service every 6 months because I ride a lot. I think for a lot of people once a year before the riding season starts is enough.
  • 36 20
 Air springs are better than coils? What's next, 29ers are better than mountain bikes?
  • 12 14
 If they sucked you wouldn't see em on pro level DH and EWS bikes.
  • 22 9
 Coils are underrated. They are so easy, buy the right spring kit adjust the preload and rebound rate and you're done! Air fork seem to be continuous fiddling with pressures and you never seem to get it just right.
  • 11 20
flag jaame (Jun 9, 2015 at 22:45) (Below Threshold)
 Of course, all those pro riders are using air because they want to right? Or is it because they are getting paid to do so? Honestly I don't think there is much difference in performance between air and coil when serviced, but you don't need to service coil!
  • 9 6
 @jaame all forks and shocks need to be serviced at the same intervals.
  • 9 18
flag jaame (Jun 10, 2015 at 0:34) (Below Threshold)
 In theory maybe, but not in practice
  • 13 30
flag jaame (Jun 10, 2015 at 1:04) (Below Threshold)
 Why are you downvoting me for telling the truth you bunch of bananas?
  • 17 2
 This is going to go against everything that PB'ers rave about - like buying the most high end $$$$ and latest tech etc etc. But low and midrange coil shocks (and we're talking real life mid-range, not PB midrange) are surprisingly maintenance free. You can get away with never servicing them, and they can still work pretty damn well. Sure they perform a bit better if you service them every 2nd ride, but even if you never service a low end coil, most usually stay quite ridable - maybe not butter, but soft serve ice cream. Try that with a rock shox monarch, and well...kiss fun goodbye.
  • 10 0
 ^^ best insult
  • 6 0
 Thanks fatenduro. I replaced a monarch plus rc3 with a DSP dueler at approx half the price. Monarch had to be serviced twice in the first three months, kept losing rebound damping and developed a click on compression. I sold it after a year and three services. The DSP has now done 3 years and two sets of bushings without a service, and still works close enough to like new for me to not notice. Also my marzocchi dj has had one service in five years, which did not make any discernible difference to performance. Air shocks are easier to set up for weight, but are not as sensitive. They are lighter, but in my experience at least they rarely work properly and need servicing too often. Service isn't a problem if your're a pro on the black box program but I'm not.
  • 10 2
 @jaame.. Because it doesn't really matter if you're telling the truth.. The neg button is a one-shot pistol for keyboard cowboys, with no repercussions. So you're bound to get shot every now and then. I applaud you for getting negged. Loving the 'bunch of bananas' too, very descriptive.
  • 6 1
 IMO.... Air shocks need servicing roughly every 12 seconds of riding....
  • 5 0
 Feel free to disagree, but according to Craig at Avalanche DHR, tons of pros run air fork bodies with coils swapped in, because they want the coil feel, but their sponsors want to show off their high end air forks that their customers buy. and apparently fork makers like air forks so much because that means they don't have to stock hundreds or thousands of 3 or 4 different weight coils for each fork that they make, in each distribution center in every country they service all around the world. that's millions of dollars of parts lying around when an air fork doesn't require any of that. so, according to Craig, it's purely a matter of economics, not performance
  • 4 0
 Sounds about right. Isn't it always about economics? (Read: the bottom line)
On another note, you've just outed Craig as the cycling industries Edward Snowden. Smile
  • 2 0
 heh- he's pretty open about his feelings about how the industry operates, but he also wouldn't have a job if these fork manufacturers weren't so terrible at theirs Smile
  • 1 0
 ... and then you get your new coil fork/shock and the stock spring is too stiff so you buy the slightly softer one and you bottom out all the time so you're stuck between a rock and a hard place, leaving you unsatisfied with the bike. Air is really cool for that, especially when you need to adjust it on the fly.
  • 1 0
 That's what the preload is for. To be fair I have only have RockShox springs but with these a medium spring with the preload wound right off, is about the same as a soft spring wound down 2/3 on the preload.
  • 4 0
 Pro riders have mechanics and an unlimited supply of parts. So yeah if it only had to last one race run or a weekend then yes run air for the weight saving but in the real world you want coils. Way more reliable, take way more abuse, service less often and work better.
  • 2 1
 Like I said, air works very well fresh off a service. Five hours later... Not so well.
  • 1 1
 I think it's ridiculous to generalize so much over coil/air. Maybe if you run a coil marzo fork its going to feel great forever with 0 maintenance but my rockshox coil forks only feel fresh for like... one run and the seals inevitably start barfing oil after barely a few days riding. Meanwhile, my F36 fork has a pretty consistent feeling and can be ridden quite a while before it shows signs its ready for maintenance. I'm not sure I could say the same about the 32s though.
  • 14 3
 Instead of a new fork, just drop an air spring into the current one. Easy and cheap.
  • 3 2
 I put a Talas 5 cartridge in my 2011 van rc2 and I it feels great. With all the negative spring advancements air is feeling pretty good!!!
  • 2 0
 Cost is about $260... but I bet he needs a rebuild
  • 20 0
 This is usually not advised as the coil spring wears the inside of the leg and provides a sub standard surface for the air seal to slide against. Air to coil is fine, but the other way isn't recommended.
  • 3 0
 However the new Talas 5 is a separate drop in cartridge and does not seal against the inner part of the stanch tube. Also, do not forget to remove your hydro bottom out in the damper side or you will not be able to achieve full travel. Now if you wanted a float then you cannot do that because it seals against the inside of the stanch tube.
  • 1 0
 What about the Marzocchi air assist on 2006 dirt jams and so on. The same is on the Manitou Circus Expert, not an air cartridge, but air cap to put some psi in the leg to help out with damping. I'd try and just put one of the suckers if it would fit the thread. Just my too sents Big Grin
  • 10 0
 I want to go the other way and Ropelato my enduro with an Ohlins. Pls donate.
  • 8 0
 If you're just looking to give away that Fox Van... :-)
  • 11 3
 good answers.. lame questions...
  • 18 3
 Good Answers.. Lame Comments...
  • 35 0
 Lame good.... comment answers.
  • 1 1
 Good lame answer comments.
  • 1 1
 The first two were good but it looks like you are just fishing for props 2020.
  • 1 1
 Cracking answer, I now know more than i did at start of today...

Good comments too.... mainly Wink
  • 6 0
 A bar with more back sweep will put your hands just as near to the centre line of the steerer with a short stem just as any other of these new fangled products
  • 3 0
 Good point, don't know if it actually works but its not a bad idea
  • 1 0
 It definitely works, since the steerer doesn't care where the bar is mounted, only where your hands are applying the force. The physics would be identical, but it's possible some people just wouldn't like the feel of the back-swept bar fit-wise.

@wobbem but what if you need your hands BEHIND the bars, like on this speed demon???? goo.gl/ezCGdo

For real though, there are limits to the benefits of short stems. I think if you're mounting the bars on top of your steerer with these hideous high-rise stems you're probably about at the limit. Do people care so much about getting the "feel" of a 10mm stem, but somehow don't care about the feel of raising your bars upwards by an inch??
  • 2 0
 I use a 9* back sweep flat bar on a 35mm stem, its ends come up about 10mm in front of centre of steerer.
  • 1 7
flag xeren (Jun 10, 2015 at 10:17) (Below Threshold)
 @bkm303 i'm not sure i agree with the physics of it. lets take an extreme example - what if you had a 10 foot long stem, attached to a bar with a 10 foot backsweep that put the bars in your hands as if you had a 0mm stem. that thing is still going to require a ton of effort to turn the handle bars

again, it's an extreme example, but it illustrates that the physics are not the same either way
  • 5 1
 The only reason that would take a ton of effort is because your 10 ft stem and bars would have a ton of mass and a huge moment of inertia. Since there's effectively no difference in mass or moment between a 40mm stem with backsweep vs a 10mm stem without, the rider would feel no difference. For leverage and steering speed, what matters is the vector from the hand to the steerer.
  • 1 0
 However much backsweep there is on the bars, the handling would be affected at where its anchored (ie: stem), wouldnt it?
  • 9 0
 Whores
  • 4 0
 I understand the value of zero length stem on downhill section but on flatter sections isn't this going to take too much weight off the front wheel making the bike feel unstable?
  • 4 0
 Eh, that's a tradeoff that people already make (compare techy climbing on say an SB5 and a XC-trail 29er full squish bike ). On the all mountain super bikes there is much more tendency for the front to lift and it's harder to track straight on very steep climbs.

These ultra short stems just take it on step farther (so yes you are right).
  • 3 1
 a coil with the correct spring will be more plush than an air spring, all else being the same. Some springs are better executed than others, of course. air suspension is better for the OEMs because it's lighter and there's no coil swapping, but for the rider it's not so clear cut.
  • 1 0
 How does one get around the inherent linearity of a spring????

Progression seems to be good, most of my customers used to add tokens/spacers to increase the ramp up and improve the sensitivity off the top, but you can't do that with a coil. How do you get that feel?

I've never run coil, I'd be interested in trying it, but I don't understand how it would work.
  • 2 1
 coils are so awesome that you don't need to do anything.
  • 1 0
 I have a feeling it's done with the compression damping cartridge, but I'm far from savvy about suspension. Maybe someone will elaborate or possibly shoot me down for talking rubbish.
  • 3 0
 Actually.. I prefer eoin-j's reply.
  • 1 0
 Higher end coils usually allow you to add high speed compression (bottom out protection) without compromising small bump sensitivity.
  • 1 0
 There is such a thing as a rising rate or progressive coil. That alone can provide a softer more responsive feel in the early stages of travel while requiring more energy as you get deeper in. There are pluses and minuses of course. Check this out if interested.

automotivethinker.com/suspension/linear-vs-progressive-rate-springs

@justincs : It's really "the damper" or shock absorber (there inside the spring) that's going to provide low or high speed compression adjustment as well as rebound and ramp up or bottom out (if so equipped). The spring is a static (non-adjustable other than preload) part of a coil setup that is affected by fine tuning the damper.
  • 1 0
 I understand that, but the higher end dampening cartridges give you the ability to tune the fork such that it can remain quite plush without bottoming out, not exactly the same as rising rate, but I think better overall for higher speed/ rougher trails! The fact that most coil applications are linear and newer air systems are trying to achieve a more linear feel suggests that a more linear spring rate has a greater advantages for most riders!(maybe that's why I haven't seen any variable rate coils available for bikes) I can understand if you require more front end pop for jumptracks, or slopestyle, air forks will give a bit more pop, but a good coil fork using maybe one spring weight higher should be able to achieve the same outcome. just my two cents!
  • 1 0
 I'd disagree with you there justin, most people seem to be looking for less linearity in their air forks, reducing volume to get them more progressive. As for using the damping, you can do that on an air fork, but I'd rather use as little damping as I can get away with...
  • 1 0
 @justincs : I suspect the reason many (producers) prefer a linear rate on the spring is because it's more difficult to get a damper to work well at all points in the curve for a progressive spring. So why bother when you can use the damper or absorber portion of the unit to tune ramp up and compression.

That said, I agree completely about the offerings of higher end cartridges. I too prefer to set up (or try at lest) my stuff to be soft in it's initial travel then ramp up. I like a rather dramatic ramp up I supposed.
  • 2 0
 Aren't you confusing Fabien Barel and Cesar Rojo? I'm pretty sure it's the brainchild of Rojo, but it could well be both.
  • 2 0
 Fer shizzle! It's actually Cesar Rojo that did the bulk of the work there.

www.mbr.co.uk/how-to-2/tech-advice/mondrakers-forward-geometry-explained-323495

I like that the article points out that you can't just slap a short stem on a bike and call it good. Guys like Mark Wier went up a frame size then reduce the stem length (www.pinkbike.com/news/Mark-Weir-Bike-Check-2012.html). And that's the forward geo stuff in a nutshell. Increase the length of the front triangle then reduce the reach via the stem.
  • 1 0
 In other words: pushing the wheel forward without using crazy headangle like 60°. Well who knows, may be we get 60° on trail bikes 5 years down the road... Some DH bikes already have this value I think.
  • 1 0
 I think the slackest out there right now is the Scott Gambler. It comes with adjust-ability and is capable of being set at 61 degrees so pretty damn close to 60 there eh? :-)

But there has got to be a limit to how far out you can push the front wheel in front of you before traction (especially in fast sweepers) becomes an issues. You have to have weight on the tires for them to work after all. ;-)

I do remember Rob Warner during a World Cup broadcast stating that Brook MacDonald actually put a 50mm stem on his Mondraker to help get better traction out of the front end. I don't know if that helped or not.
  • 1 0
 @BDKR

Thats exactly my thinking.....

My frame is an L, and tried a M, it just didnt feel right...
  • 1 0
 @BDKR: I think the Gambler can also be adjusted +-2 degrees, which would mean down to 59!
I think Fairclough rides with 60.
  • 2 0
 Quite pleased to get so much good advice about the stem im using.. Proper nice community on PB.. Big up......
  • 3 0
 It was bound to come.
  • 2 0
 Pretty soon we'll all be riding 4wd Segways downhill.
  • 1 0
 Would love to see a Segway with a Fox Air shock lol

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