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Posts Categorized: Leo’s tech blog

Näyttökuva 2017-06-21 kello 15.10.07

How to set up your Pole

by in Leo's tech blog

Watch the video below

1. Check the tire pressure

Tire pressure plays very important role how your bike handles. A harsh ride can be caused from over inflated tires and also you may lose traction. Your tire pressure should be set as low as possible without puncturing tires, damaging rims, burping tubeless or tires rolling sideways. Huck Norris is a great product that can help you to get tire pressure lower without damaging tires or rims.

2.Firm Pole is better than soft Pole

Your bike should be responsive. If your Pole is set too soft, you will have performance issues like bike is using too much travel and you are loosing speed or the worst case scenario is excess nose dive in breaking or hucking. When you increase spring rate you need to remember to add more rebound damping. If there is not enough rebound damping the bike feels like a jumping stick and if there is too much rebound damping the bike feels dead underneath. In between these scenarios is a setup that is responsive, stable and playful.

3. Set your seat according your riding style

Your riding style determines where your seat should be set. If you are riding uphills your seat should be as front as possible and if you are running on flat sections you can push the saddle a bit backwards to get better balance for pedaling. If you want more upright posture for ergonomic reasons, just push the seat in front. If you ride only riding lift assisted rides your saddle should be nose up because your bike’s front end is pointing more or less downhill. If you are riding flat, your saddle should be parallel to ground. If you are riding up and down the mountains your saddle should be nose down. The reason the saddle position is nose down is that in uphills you can save a lot of energy when your bum is not sliding off the saddle.

4. Check Your handlebar height and position

When your seat is positioned correctly handlebar height determines how much your body weight is distributed to the front wheel. If you feel that your front end is too light and you feel twithcy when ascending, just move one 5mm at a time from under the stem to top of the stem. This is a good indicator that gives you the right handlebar height to the descending as well. The more upright you can stand without losing traction on front wheel the better it is.

Make sure that your handlebar’s backsweep is pointing right direction. The most common mistake is to turn the handlebars so that the backsweep becomes upsweep. The handlebars should turn towards your body

5. Other tricks and tips

If regarding all the above you encounter loss of traction in front, try to add one or two clicks of low speed compression. The reason behind this is that your fork is giving out too early in the corner. On long bike you can not load the front end that strongly so it’s easier to add more compression damping.

If you are riding very steep sections it helps if you lower the seat 20-30mm from the ideal position. Because we have a steep seat tube angle the saddle sometimes comes in the way when you are turning really tight switchbacks. This trick works also in singletrack trail riding where you very seldom want to extend your telescopic seat post all the way up. Let’s call this as a trail setup.

Check your brake lever position. They should be more level than pointing downwards. This helps your arms to relax and takes off your weight from front when braking in descends.

 

Pole-EVOLINK-140-2017-savonmaki

The 2017 EVOLINK

by in Leo's tech blog, News

Our EVOLINK frames gets some new features on 2017. Here’s the changes we did and stories behind them.

1. Rear hub standards

The BOOST rear hub standard has been around for a while and we are convinced about it. Also, we know that people still have 142 wheels. We designed a clever system which allows the user choose which standard he wants to use. The adapters for each standard are designed so that there is no compromise on stiffness and there is not a complicated bolt on systems that eventually come loose or even drop off. The system has a new hanger which works as an adapter as well. On the non-drive side there is a press fir adapter and for the 142 two 3mm washers for the I.S. mount. We think this design is so clever that possibly some other brands will copy it later 😉

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Leo_Laajis_EVOLINK150_2016

Where did the new school geometry come from?

by in Leo's tech blog

If you are a bike designer from a competitive bike company, you should stop reading because I will explain the past and the future of mountain bikes here 😉

First we need to understand where the mountain bike industry comes from. The bicycles were firstly intended to be ridden on man made surfaces. At some point someone wanted to ride the bikes on trail. Here is where it gets complicated. The rider experiments a lot of problems and tries to resolve them one by one. The first thing is to make the tire air volume bigger to make the riding safer and comfortable. After that we have seen a huge variety of new innovations from high end suspension to a electric drivetrain, yet still simple new innovations makes the riding easier and safer. A good example of a simple innovation that makes descending safer is a dropper post. What comes to bicycle geometry it has developed on DH bikes but for XC bikes it has not changed a lot throughout the years. The reason might be that people got used to a certain geometry and it’s not easy to learn new stuff. Although the riding has become more progressive and people are looking for a different thrill. I believe that the XC geometry has been adopted from road bikes.

Where did Pole start from?

I had a huge crash at Jyly 2011. My grip slid off the handlebars when I landed a step down too short on a downhill track. I dislocated my hip and had to recover from that. I had to ride a XC trail bike for a while and the bike just felt wrong. A DH bike is a nice bike to handle even on flat but it’s seat angle is just wrong for pedaling. XC bike feels wrong for me in any way (by no offence to anyone). I think that the normal XC bike is just too much of a road bike. On a XC bike I feel that I’m on a juggernaut-cannonball posture even you are riding less than 25km/h and at downhill I’m scared because the front wheel is too close. This posture is not good on a technical trail because the balance is not easy to keep when your hips are bent. What I did was altered my K9 DH001S so that it was more to my liking. I installed a 140mm fork and put the slackest headset (-2°) to compensate the head tube being lower. This made the bike’s seat tube more upright so that you could pedal the bike. This video has been filmed on 30.9.2013 at Jyväskylä Finland. In the process I started to love uphill climbs and Enduro competitions.

Why big companies are not following us already?

Big companies are not interested in things that are not easy to explain. I see many reviews where it’s said that the bikes are slacker and lower but they really aren’t. The big companies want something that is easy to sell to masses. New school geometry is not like a new standard like boost or 27.5″ which is pushed to the market. A new thing is going to be pushed to market if the dealers see something that is easy to sell. Ebikes are a good example of new stuff what is easy to sell because you can make anyone climb a mountain with a help of a motor. That expands your market and you hardly need to learn anything new. The dealers are even selling the illegal kits to make the bicycles to motorbikes to make a sale. A new geometry is hard to sell because you need to learn new stuff. For big scale this is hard because there will always be something lost in translation. This is one of the reasons why Pole is not going to be sold by anyone who wants to. We are very strict how our products are sold.

So why don’t people demand the change from the big companies?

Many riders are not engineers and they don’t know about mechanics, physics etc. Also you need to have a desire and passion to push these ides forward. Also many of the bicycle engineers are not riders so they can’t understand the riding as well. Engineers tend to focus on making the bike lighter and cheaper to manufacture. Also it’s about history and what people are used to. You could ask as well why XC is not catching slacker head angles? For XC bikes the slack geometry should be a no brainer. Most of the XC bikes are steep. Why is that? The XC bikes are pedaled most of the time on gravel roads anyways and there are no tight turns what so ever. So that’s that with the short wheelbase if anyone still thinks the long wheelbase is too hard to turn. The aerodynamics does not have a big role either. Every now and then you see a video of a racer who enters the “technical section” of the track. The racer is in trouble because the bike has rather a road bike geometry (short and steep). The stem is long and the weight is on the front. He tries to put his weight to the back but because the short wheelbase, the bike’s angle on a drop is too steep and the bike slings the rider over the bars because he’s arms are stretched out. The other scenario is that the front end does not give him a hint where it’s going because the short trail and the handlebar turns suddenly 90°. We need to remember that road bike geometry is defined by UCI and there is not much wiggle room there to get innovative. I would not imitate road bike geometry on mountain bikes. How many of these OTBs would have been avoided by longer and slacker bike?

What’s the big deal then?

It’s just a simple solution to a problem that most of the riders don’t even know that they are struggling on. By changing the geometry of the bike, we move riders weight to a right position between the axles and change the posture of riding more upright. This makes it easier and safer to ride. Safe + easy equals to more speed, it’s that simple. Sometimes innovations are not very complex. Actually, the best innovations are simple, just like Huck Norris.

Does the new school geometry fit anyone?

Short andswer: yes. Some people catch on the geometry immediately but some people need a couple of runs or more. We changed a lot of things along the way when we started to find the new school geometry. Because we changed the bike overall the riders needs to change their riding style and timing. The rider’s body movement on a longer bike should be more up and down from the center of the bike. The idea is to stay between the axles and don’t hang back. If you need to rise your upper body on a steep track, you can put handlebars higher. Some people would want to shorten the chainstays but that hardly helps because it just takes the weight off the front wheel but your body is still on the same posture. This means unstable ride. The right thing to do would be to make the bottom bracket lower but this is mechanically quite hard without changing the bike too much.

Suspension needs to be more sensitive and differently tuned for a longer bike because your weight balance is just different. It makes a huge difference on the weight balance between the axles when we push the rider a few centimeters forward in the cockpit and make the front center longer. Of course we compensate this also by adding more length to the rear center as well. All together there are many things you need to look differently but it’s not as hard as it sounds like. Beginners get on with this geometry very fast.

Why Pole is using the stock offset on forks?

If you don’t know what fork offset is, you don’t necessarily need to read this part, but if you want to understand, read this first. I tried different offsets and what I found was that the short offset makes the bike unstable in slow corners. In fast speeds it’s ok but I rather add more wheelbase than make it shorter. The short offset works if you have good stamina and power on your hands but when you are descending long your hands gets tired and when you enter some tight and slow switchbacks it’s harder to stay on the bike. Therefore I rather made the head angle slacker and take the 51mm offset for the 29″.

Pole EVOLINK 150 plus 29

I think that the 29″ is a no brainer. The traction is awesome and it just makes the bike go over a lot of stuff easier, which means faster and safer rides. Last summer I experimented some crazy options as well but I feel that the 29″ on both ends is more consistent and it makes your life a lot easier not to have to deal with different tire sizes. I’m trying to find simple solutions to make the bike easier and safer to ride because that equals faster rides. My fun comes from reliable rides. I’m trying to make the bike feel like you are flying a fighter jet. One line rather than skipping all over the places.

After Seb Stott mentioned the longer stem length on Bikeradar review of the EVOLINK 140 I have been asked a million times, what stem length should you choose. My take on this is that if you don’t have grip on your front wheel, you need to add support to the front. This means that if your SAG is right you need to add low speed compression. The reason you don’t have grip on front that the fork does not give you support when you are pushing it. The stem length depends of your height and your arm length. I changed my stem from 35mm to 40mm on a size M bike. This is a minor change but I’m between the L and M so this change gave me the best balance between the sizes. Seb is over the L size so he definitely should add some reach to his bike.

Here are some clips from various levels of riding on Pole bikes (Pole means “pedal!”). You can spot Matti Lehikoinen riding there as well.

0:08 Santeri Siltala (Men Elite) – EVOLINK 140 L
1:14 Onni Rainio (14yrs) – EVOLINK 150 XS (1st)
2:38 Kaisa Härkonen (Women Elite) – EVOLINK 140 S (2nd)
2:54 Suvi Vacker (Women Elite) – EVOLINK 150 S (1st)
4:19 Leo Kokkonen (me) (Men Elite) – EVOLINK 140 M (3rd)
4:46 Juhani Kettunen (Men Elite) – EVOLINK 150 M with 29″ wheels (4th)

And a very tight Switchback from the same competition.

My guess is that we have five years until the entire industry adopts our geometry.

Pole new School of MTB

New school bicycle platform

by in Leo's tech blog, News

 

POLE BICYCLES PRESENTS GAME CHANGING SLACK BIKES

If you want to design your own bikes and test ride them thoroughly then Finland might not be the best place to do it. Especially during the winter months as the weather is a mix of rain, snow, cats and dogs. So we decided to pack our bikes and head to Spain to test our prototype models. I met a bunch of French guys at the Switchbacks in Bubion village. They had started their mountain biking in the seventies by removing the motors from their mopeds, pushing them to the top of the hill and enjoying the ride down on steep alpine slopes. I was amazed by their commitment to the sport and technical skills on the bike. They called us, who are not boys anymore by any standards, as the “new school”. I was intrigued by their definition as I have never thought as classifying myself to any type of riding, just riding my bike the way I know and enjoy the most. Their definition of “New school” was going fast all the time, jumping over the technical stuff and dressing stylishly. I wasn’t too sure of the last point, but the description of riding was spot on.

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Bicycle dynamics and pedaling efficiency

by in Leo's tech blog

Pedaling efficiency in suspension bike depends from many variables. There’s nothing really special about the physics to person who is educated in physics and mechanics. If you want to market something the message has to be simple. That’s why companies, media and riders have made the bicycle dynamics very confusing. The full suspension market is also very young and there is a lot of young persons for market the stuff, which makes it tending to make stuff sound cool.

I want to break this loop by explaining the bicycle dynamics. The rider is the engine and the bicycle is a vehicle, that’s it. There is no magic. I’ll rule out the rider skill because a good rider can adapt to different systems and ride fast with any bike. In the previous blog I explained how the Anti Squat works. Anti Squat is a term for suspension engineers to determine how much the suspension mechanism itself is resisting suspension compression. AS resists the pedaling forces from compressing the the suspension.  We need to look at the loads and forces which are involved in the cycling.

Pole VOIMAT illustraatio

Weight and suspension

In the first part here I’ll rule out rider weight distribution and I’ll just concentrate on the up and down direction forces. In bicycle the engine is the rider. In any vehicle the motor needs to be attached to the frame. On bicycle the rider is attached from the handlebar, and from the pedals. When rider is creating force the support comes from the handlebars only. If the rider is not holding the handlebars the rider is using some of his energy to lift himself up when accelerating. This can be implemented by trying to accelerate stationary bike without hands on the handlebar. If the rider pedals optimally he’s body remains stiff and only the legs are doing the job.

When rider is on the bike the rider mass creates a force down (because of the gravity) to the bike and the bike creates a force back (Newton’s third law) . In suspension frame the suspension compresses as much the spring is set. In the fork the leverage ratio is 1:1 (without leverage) and in the rear the optimal leverage ratio is between 1:3 to 1:2 and the leverage ratio in rear is changing through the travel because all the bikes are using rotary leverages. When bicycle accelerates, brakes or hits an obstacle the mass of the rider and the bicycle are resisting the change of the speed. The suspension is designed to absorb the hits and convert the energy of the mass and speed to heat.  The forces and the bicycle works with these rules when bicycle is coasting.

Pedaling forces

When rider pedals the bike he’s creating forces from his body with muscles which get energy from food. The rider takes support for the pedaling from the handlebars which are attached to the frame through fork and headset this makes the front triangle and the rider together a closed system. The force transferred to the pedals create a force to the rear wheel through chain and the force is delivered to the ground by wheels and tires. All the energy can not be delivered to the tire because there’s friction from the chain and the bearings and the frame is twisting the energy to heat as well.

Weight, suspension and pedaling forces

Now we are getting to the interesting part. Because we are talking about a mountain bike it’s not reasonable to assume that the bike is traveling an smooth surfaces. There is always a bump or two on the way and this is why the suspension is there for. There is two scenarios when the rider is pedaling. 1. Accelerating 2. Keeping up the speed. Every pedal stroke is accelerating the vehicle because the pedaling motion is an oscillating motion and the friction from the world around is slowing the bicycle down all the time. The more continuous is the output force, the the better pedaling technique rider has. In uphill the rider is constantly accelerating the bike on every pedal stroke because the bicycle speed is dropping between every pedal stroke. In our experiments (and the basic physics) the rider and the bicycle loses energy most is when accelerating.

Where the energy is lost in pedaling

1. Mass resits the changes in movement.
2. Suspension is compressing (Anti Squat <100%) and generating heat from the damper
3. Suspension is extending (Anti Squat >100%) and the force is used to lift the rider from the SAG position
4. Frame is losing energy in friction and flexing
5. Bad pedaling technique (fe. hip is rocking sideways)

How suspension works

The idea in suspension is to eliminate the obstacles effects to the rider mass as less as possible. Spring carries the load and the damper takes out the unnecessary movement. If the spring is too stiff compared to the rider mass, speed and the strength the suspension can not compress enough to use it’s full potential. If the spring is too soft the suspension doesn’t carry the load and the suspension sinks too deep in it’s travel. When this happens there is not as much travel in suspension to use and the damper is not working on the optimal area. If there is too much damping the suspension converts the speed to heat. If there is not enough damping the obstacles effects the rider mass and speed slows down. There is a certain sweet spot between all these setups.

How Anti-Squat loses power in pedaling

Read this article first. Everything starts when the rider climbs on the bike. The rider creates sag to the system and then the suspension is compressed. When the rider starts to pedal he’s grabbing the handlebar and pushes the pedals one by one until the bike reaches it’s desired speed. When the desired speed is acquired  rider uses rotary motion of the cranks to keep the bike moving. The biggest energy loss is always in the acceleration phase.

>100% AS in acceleration

If the system has AS more than 100%  the suspension is generally extending in the acceleration. The power transfers easiest to the extending movement of the shock because of the spring potential. Only force resisting this is the rebound damping. The suspension extends because the rear wheel has resistance due the friction of the tire-ground contact and because the rider and bicycle mass is resisting the movement forward. When the bicycle is accelerated very fast and the force from the rear wheel is greater than the rider-bicycle mass  leverage force, the bicycle and the rider rotates around the rear wheel because it’s the easiest way to deliver the energy. Wheelie depends of the forces resisting the rotation which are combined from the leverage ratio of the rider and bicycle mass-centre drawn vertical between the tires and the mass resisting the movement and the friction between the tire and the ground. Wheelie is needs as well support from suspension so if the forces are greater in suspension to hold the body from compressing or extending the wheelie is possible. When the >100% AS is extending the compression at the same time as the bicycle wants to make a wheelie the rider-bicycle mass leverage is weaker.  The energy is lost in lifting of the rider mass the front end is lifted or the AS is lifting the rider weight. Rider can compensate the wheelie by leaning forward but in uphill it can be difficult. There is also the downsides from the >100% AS pedal feedback which are explained in the previous blog post about Anti-Squat and Pedal-Kickback. There is also possibility to loose grip in accelerating because the suspension is not active in this scenario.

<100% AS in acceleration

When bicycle has less than 100% AS the suspension is compressing in the acceleration. The compression can be controlled by low speed compression settings and the spring load. When the suspension tends to compress no undesirable weight transfer in the acceleration and no weight is lifted by the suspension in the acceleration. The compression in the suspension will returned by the spring so there’s no energy needed to get back to the SAG-position. In this setup there are not as much defects from the pedal feedback. The grip is also good because the suspension is active.

How to determine how much?

The energy loss can be measured with power meter, heart rate monitor and a stopwatch. This is a good way to estimate how much energy is lost in the process. If we compare the time, energy used and energy put in to different systems we can say which option is the best for the rider and the terrain. We only test by stopwatches because there is no room for guessing. Time doesn’t lie.

What is Anti Squat and pedal kickback

by in Leo's tech blog

I’ve been part of many discussions about how Anti Squat (later AS) effects the suspension. I’ve noticed that it’s not an simple way to explain this but I’ll try.

Anti Squat (AS)

Anti Squat is a term for suspension engineers to determine how much the suspension mechanism itself is resisting suspension compression. Anti-squat is suspension’s mechanical resistance to compression due to forces from the engine (on bicycle the engine is human). Over 100% of anti-squat (AS) means suspension will extend under acceleration. With 100% AS suspension won’t neither extend nor compress. Under 100% AS means tendency to compress under acceleration. It is determined based on actual linkage instant center (IC, pivot point is also used), chain force line and center of mass height.

Over 100precent Anti Squat

Over 100% of anti-squat (AS) means suspension will extend under acceleration.

What we’ve learned from our testing is that, if the AS is more than 100% it needs more effort to pedal uphill since the pedaling effect wants to lift rider weight. Also the suspension is harder to tune for downhill riding because of the extending forces of the AS.

Under 100precent Anti Squat

Under 100% AS means tendency to compress under acceleration.

We’ve learned that if the bike has less than 100% AS it’s easier to control the forces with shock tuning.

With 100% AS suspension won't neither extend nor compress.

With 100% AS suspension won’t neither extend nor compress.

100% of AS is impossible to maintain. The bike can have 100% AS in one point of travel but it can not maintain it.

Pedal-Kickback

Pedal-Kickback means the result of chain growth rotating the cranks backwards during suspension compress. Pedal-Kickback effect is a byproduct of anti-squat characteristics of the suspension. When bicycle is designed to use AS the swing arm is on a  different axle than the cranks. The chain is connected between the chainring and the cassette. When the suspension compresses, chain needs to “grow” or give out from either end of the chain. I’m only talking about the top part of the chain. The lower part of the chain is another case.

 

Why speed doesn’t count

There is a general opinion that the faster you are going the less pedal kickback you are getting. There is only one thing you need to know: the compression takes place always at the same amount of rotation of the wheel. It just happens faster and with greater force if the bicycle is going faster. You will also hit some bumps while pedaling and then you are generating force at the same time to the system which means that you are same time fighting to get the rear wheel rotating and resisting the bike from compressing. Here is the theory behind the pedal kickback: Pedal Kickback Calculation

Pedal Kickback

Braking

We need to add one more thing to this equation. When you travel in speed you most likely brake every now and then. The braking also effects to the suspension. It either compresses or extends the suspension. When you hit those braking bumps on the trail and hit the brakes at the same time the suspension is not as effective it could be. When the rear wheel can not move the pedals need to move. This gives again pedal kickback and when the rider stands on the pedals it makes the damping harder. The braking is also generating either squat or rise. If the bike tends to rise and the bike has a lot of AS it’s generally called brake jack. With all these together the suspension becomes super hard.

What do I think?

Anti Squat is a good way to make the pedaling feel firm but all the results should be measured with a stopwatch rather than bragging about the perfect concept. We’ve learned that even the bike dynamics looks good on paper it doesn’t necessary perform on the trail. There is many other factors which effect the bicycle performance than AS. Geometry, derailleur, overall chain growth, rider style, tires, frame stiffness, leverage ratio, travel, shock type and aerodynamics. All this together makes the bike but the most important thing is the rider. We can make a bicycle which is easy to ride but we can not make the rider change their way of riding. The AS is good and bad at the same time but if we can control it’s effects reasonable it can be good. Modern bicycles are very effective but still Aron Gwin won in Leogang chainless = without AS and pedaling.

My first bicycle concept is the PoleLink™. Polelink is concentric which means that we control the squat effect with the shock tune rather than mechanical features. The pedaling forces are divided between the wheel and the shock. With good low speed compression settings the rear doesn’t squat much and the forces from the chain are not effecting the frame. This system also saves the need of chain device and gives longer life for the chain and the chain rings because the system is not under large stress on compression. This gives the suspension more freedom and makes the bike easy to handle. This bike is very different from the current market because the main thing controlling the AS is the 1X11 drivetrain This system is not safe for the pedal kickback because it’s kicking when the bike is decompressing but since it is slower movement than in compression so it’s not as harmful.  Our Polelink bike was reviewed in Pinkbike

Rinne Ylä Studio NDS

Future

We can build a bike which suspension starts from 100% of AS and when the bike compresses the AS will drop to zero through the travel and has minimum amount of total chain growth. Also it should have under 100% of anti rise. The leverage ratio should be progressive since the AS will resist at the beginning but when the bike goes through the travel the resistance fades out and the leverage ratio is lower. Low AS at the end of the travel is also good for the frame as it doesn’t have to be super stiff. Our insight is that if the bike has stiff rear axle and front triangle but can flex from the middle it handles easier. To fine tune this system I will use an air shock which air volume can be fine tuned to suit the riders preference. We’ve already made a prototype of this bike and we are fine tuning it at the moment. There will be five bikes with the same suspension layout.

Leo Kokkonen riding corners with the new Pole Evolution Concept.

Leo Kokkonen riding corners with the new Pole Evolution Concept.

 

Geometry

We have learned that long bike with generous reach is easy to ride fast. Short bike needs more skill to keep it balanced. With slack head angle it’s possible to ride corners like a pro. Longer chainstay keeps the long front centre balanced and keeps the bike stable in high speed. Long bike is not hard to turn. It just needs a new timing.

Laajavuori DH Cup Antti Lampen 6_2016

Antti Lampén racing at Laajavuori.

 

Leo kokkonen
Indutrial designer and founder of Pole Bicyle Company

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