|We can go as long, low and slack as needed - it's all about finding that happy place. If you put the rider in their happy place for their speed, style and location, it will all come together. Faster riders with steeper and looser trails on their doorstep will benefit from more extreme geometry while other riders who perhaps find themselves on less progressive terrain might find that such geometry is too extreme for their style and trails, and will ultimately make them slower. The bike needs to disappear under the rider and become an extension of their body.|
The advantages of such extreme geometry allows riders who regularly find themselves on demanding terrain, the ability to ride with the kind of speed and style they always dreamed of. The drawbacks are that they climb a little slower than a bike with traditional geometry and the front end tends to wander more than it would do on a bike with a steeper head angle. As long as the bike is confidence inspiring and encourages you to take the most aggressive line that your mind can envision, then we are on the right track, providing, of course, that's what you want and need.
Ultimately though, I think it's all coming together. On the whole, riders are getting better as well as the quantity and quality of the trails out there, which in addition to all the frames and components, which are also getting stronger and lighter as well. I think it's a combined effect and geometry is merely catching up. These new evolutions are another tool to put the end user on the best possible bike for their needs. If someone wants to ride a certain trail in a certain way then we need to cater to those needs. For me, living in the Alps with Champery on my doorstep, a longer, lower and slacker bike suits my riding style and the spots where I like to ride. I love trying out extreme setups to see if I can push harder and get through sections with more speed and control and in the right situations and where such attributes are a huge advantage. I think we - as an industry - are not even close to the limits. Sure, there are a few examples out there, but overall we are creeping towards these more extreme geometry setups. However, moving forwards, we will probably have to steepen up the seat tubes to keep them climbable as there's far more to extreme geometry than just slack head angles, low BB's and long front centres. The evolution continues...
|Bikes that are both longer and slacker handle better than those that don't. It's as simple as that. Bikes with slacker head angles roll faster and are as stable around corners as much as they are in straight lines. The extra length allows the rider to weight the wheels independently and focus on being more dynamic on the bike. Such bikes also allow the rider to be more pro-active with their steering, removing that nervous twitchy handling sensation we've all experienced. But here's the problem. You can't simply fit a steep seat angle (for climbing!) and a slack head angle into a frame unless you grow the bike in the first place.|
A limit may exist as to how long and steep we can go with bike geometry, but we haven't gotten there yet. Why don't we turn the question around and ask where the limit sits for bikes that are too short and steep? There are limits in both directions, but right now, we're at the sh-t end of the handling spectrum, especially when we exist in a more fashion-focused world. A world where I've seen 29ers with steeper head angles than some road bikes. I've heard some people say that this 'new' geometry is only for experts. So we should let the novices, beginners and weekend warriors all ride the sh-t bikes then? Are we (the industry) trying to kill our customers? Experts and beginners alike can all benefit from a bike with a more dynamic geometry design.
The biggest misconception surrounding this subject is that it's merely a trend. It's not a trend. A trend is 'this season's' pastel shade of pink or blue and wearing goggles and an open face helmet. Making bikes handle better should be at the heart of the MTB industries efforts right now, but seemingly not many people actually designing bikes, understand how they really work. There are however many people in the industry who understand exactly how high their socks should be this season or whether they should have stickers underneath or on top of their helmet peak. Geometry is engineering not fashion.
|We could make a statement that today's bikes, which are increasingly longer, lower and slacker, represent "modern MTB geometry" as we know it. Looking back most of the old school bikes were in stark contrast short, steep and tall, with slack seat angles, which ultimately made them very awkward going both up and down, especially on steep terrain.|
Looking at a solution to counter these performance shortfalls is not just a matter of going longer, lower or slacker, but about getting the best compromise for the application at hand, be it XC, trail, enduro or downhill, At Mondraker we started to experiment with the original idea of 'Forward Geometry' back in 2011 by just going longer in the front center and maintaining everything else as is, which proved to be a good approach five years ago.
We initially started experimenting with the Foxy, our mainstay trail / AM chassis, welding an XL top tube (which was 60mm longer) onto a medium sized bike. This would normally have a 70mm stem, but utilising a super short 10mm stem instead helped offset the growth in reach gained through a longer front centre. Doing it this way allowed the riding position to remain the same, but the level of control, handling and confidence evolved to a whole new level. On the Summum DH bike with Forward Geometry, we had Damien Spagnolo finish 2nd at the 2011 downhill world championships in Champery, Switzerland, proving the concept worked in the most demanding of environments.
Forward Geometry was later officially introduced into production bikes in 2013 and today's Mondrakers share the same principles of the original ones: longer, but not the slackest or the lowest. Geometry as a whole, for any bike, needs to be proportional to the task at hand. We have seen other brands go crazy slack on the on some of their trail or enduro models, but doing so sacrifices performance on everything except steep downhill trails.That is unless you only ride downhill trails and rely on shuttles or chairlifts to get you back to the top. But how far can you push things? Is a 65-degree head angle too slack and a 13" BB too low for a trail bike? It just depends on the bike, the rear suspension design, its intended use, plus a whole host of other factors that make modern geometry more complicated than simply adopting a longer, lower and slacker approach. At Mondraker we do believe that Forward Geometry inspired other brands to follow suit and that is something, that as a small bike brand, we are really proud of.
|The premise of the question supposes that all things must go too far in a given direction, and then reverse back to some "perfect solution." But it's nowhere near as simple as that. This is something evolutionary that riders and bike designers explore and influence together.|
Bottom bracket height dictates only the height of the BB (not the handlebar) and choice comes down to a balance of rider preference versus terrain. Some riders prefer increased clearance over cornering stability while others will trade pedal strikes for that rad drifty control and only the rider can make that judgment call. If your BB height's so low that you're on the limit of clearing features on your home trail - then that's probably low enough.
If a rider doesn't have enough front wheel traction to corner effectively then maybe the bike is too slack for their riding style. Slackness impacts other considerations such as the ability to climb certain terrain or navigate switchbacks for example, but on the whole, we're noticing traction as the principal driver behind head angle choice.
At least no one is trying to ram new head angle or reach standards on anyone. If you don't like the geometry of a model or size you don't have to ride it. Our job is to make bikes people feel good riding. It's about enabling riders to find their own specific preference or sweet spot and not forcing people to like the same thing that I do.
Take the Syndicate for example. The V10 we custom built for Peaty's World Champs win in 2009 was considered "huge" by our standards back then, with a whopping 431mm reach - that's medium Bronson territory these days. Shortly after, Greg won two World Championships on the new XL size with a 446mm reach. In 2015, he won World Cup races on an XXL V10 with 470mm of reach. So one could assume longer is faster right? Not quite. Josh Bryceland is almost identical in height to those guys yet chooses to race on a large V10 frame with 424mm reach. Those guys choose the reach they feel most comfortable with. The more comfortable they are, the more fun they have, The more fun they have the faster they go. And that's about the only thing we can all agree on.
|This is a great question and it's something I've been thinking about for some time now. Mountain bike geometry has come a long way in the past few years and my gut tells me that there is still some way to go. Will things get longer? Most probably, but I don't think we can go any lower as we still need to pedal these things after all. It's the issue of a slacker head angle where it gets really interesting and it's where I also think we need to look at this question as (initially) being more category specific.|
In the 200mm (downhill) category, where geometry is generally being pushed more than any other category, I can't help but feel we are reaching the limits of steering geometry already. I think bikes might continue to get a bit longer here, but I think future DH improvements are coming, but from somewhere else.
For the 150-170mm (enduro) category we have seen significant advancements over the past few years, and modern 'enduro' race bikes have geometry that is starting to approach that of DH bikes. The biggest thing holding back steering geometry in this category, are fork offsets. With current fork offsets we can't push head angles (slacker) without negatively affecting the ride experience. It all comes down to that trail number!
Now the 140mm (let's call it 'trail') category is where I see the biggest opportunity for geometry improvement. Most people would look at me like I was crazy if I pitched a 120mm travel trail bike for the masses with a 65-degree head tube angle. But hey, why not? Think about that one for a minute...
|With more purpose built trails and better bikes these days, people can ride faster than ever before. A direct result of that extra speed is the need for longer bikes to increase control. Longer wheelbases are good for better stability and delivering a smoother ride on fast and rough trails, help to reduce the risk of going OTB when it gets steep, and keeping your front wheel planted when climbing. That makes longer setups not only beneficial for DH or enduro, but for short travel disciplines too. It also doesn't matter if you're a first timer or an experienced rider.|
But length should only increase relative to the speeds being ridden. We need to find the right balance between agility and stability while also ensuring that the center of gravity is positioned evenly to both wheels. We can't simply keep extending the front center because you still need to apply enough pressure through the front wheel - otherwise, cornering becomes a problem.
For me, enhancing a bike's stability through its front center is more about hitting the right compromise between reach and head angle in relation to cockpit length and width, in addition to chainstay length. Extending reach, slackening head angle and fitting a short stem with wide bars delivers extra stability from the front center, handling agility from the cockpit, plus enough pressure on the front wheel. By altering chainstay length we can either increase stability or agility depending on whether you go longer or shorter. The most important thing while playing around with these different factors is to ensure that the center of gravity remains central.
|Everybody is using the words "modern geometry" right now and over the last few years there has been some noticeable changes with regards to angles, BB drop and reach. To say how far it's possible to go with these parameters is - I believe - not possible. Depending on the bike and its intended use (defined by the travel) we will always have to consider that that there will be no pair of riders with the exact same physical measurements. But there is also such a big diversity in riding skills amongst consumers who all buy the same bike making it even harder to presume how far is too far.|
Granted, a racer can benefit from a longer reach, but the average rider might have problems. As a frame designer, I always have always worked to find the best balance between these parameters to get the best possible bike for (nearly) everyone, but in the end we all want to sell bikes. However, looking at the diversity of the different bike categories available, it is more or less possible to evolve a bike in a certain direction. An enduro bike, for example, can be more extreme in its geometry than a trail bike due to the smaller group of possible buyers. On a downhill bike, these parameters can be more extreme yet again, but there are limiting points. At the moment, everybody is experimenting with these parameters and I think that most of the products that are available on the market now are within these borders, but perhaps not all.
We must also not forget that these geometry changes came from extreme riding conditions and with that in mind, we might not get the same (positive) results across the board. This is evolution, plain and simple and done by trial and error. So geometry improvements are more or less a steadily on-going process that will probably not end. And there are so many parameters that influence this process such as the trails we now ride and the advances in kinematics and suspension technology we now have at our disposal. We're all riding so much faster now as well and with that speed comes the need for more control, especially when things get too nervous on the front end, needing more effort to get it around a corner for example. Currently I see most of the extremes on the market being focussed towards a small group of customers and their preferences.
|Long: It seems there's still some room to go longer. It used to be that you'd want to keep the wheelbase short to get around tight corners. Today, suspension is allowing us to go faster and the trails are being built specifically for mountain bikes. That means that the cornering radius are larger and you don't need that tight wheelbase to snake through turns.|
Low: Looking at static BB height is not a very complete picture. What really matters is where it's going to be when you're riding and it's not as simple as where you set sag. Some bikes that have a very flat spring rate through the middle of the travel are going to have you between 25 and 75 percent and cause a lot of pedal strikes. A frame with a more progressive spring rate will keep you closer to the sag point more often. That means it will have less pedal strikes even if it has the same or slightly lower static BB height.
Slack: Just talking about head angle is over simplifying things, as 'trail' is the most important number. How much trail you want depends on what speed you want your bike to be optimized for. The trail on the HD3 and LS for example are around 100mm - more than that would make the steering feel more stable at even higher speeds, but feel way too slow at low speeds. If speeds get higher and trails get straighter we'll add more trail, but it's all a compromise.
|Today's downhill bikes established the current limits for both head tube angles and wheelbase lengths. These are now pretty similar to off-road motorcycles and I think it's safe to assume that DH bikes aren't going to get much slacker or longer. This progression has established the operating limit for head tube angles at around 62 degrees, but I also think that head angles in the range of 62-63 degrees will be used on any bike where stability and speed are important.|
Away from DH bikes, the growth in 'reach' has been driven by the increasing number of capable 160mm travel bikes (you can call these 'enduro' if you like) that have flooded the market. These bikes use slack head angles similar to a DH bike, but unlike a thoroughbred DHer, need to pedal efficiently uphill as well. The bar and pedal position (stack and reach) are what counts when you're pointing downhill, but for an AM bike, the seat position - which is important for climbing - adds another element to consider. Utilizing a steeper seat angle helps to keep weight over the front wheel when climbing and prevents the front wheel from wandering - especially on a bike with a slack head angle.
Lowering the BB helps to keep the center of gravity nice and low, which is great for going downhill, but at the same time, can adversely affect an AM bike thanks pedal strikes. Because of this issue, BB height is limited by a rider's tolerance to catching their pedals - I think that the average 160mm bike can get quite a bit slacker and longer, but I don't think there is really a need to go any lower. Reducing the center of gravity can be accomplished in a lot of other ways such as thinner pedals or even thinner shoe soles for example. As a frame designer, I look at the BB drop relative to the rear axle instead of the actual height of the BB from the ground.
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