mountain bike fork

Is It Worth Upgrading MTB Forks? Fork Suspension Upgrade Guide

mountain bike forkI remember my first time deciding to do some upgrades on my bike. This was the only bike I had at the time so I was trying to make it into something it wasn’t supposed to be. I guess that’s a mistake a lot of people do, judging by the bikes I’m seeing around.

But the most difficult question was; Is it worth upgrading MTB forks??

Judging by the value you get, a suspension is always within the top few upgrades to recommend. Especially, if a fork suspension you have can’t keep up with your skill level. Fork suspension will increase the capabilities of your bike way more than upgrading, for example, the drivetrain would.

Importance and value

The first thing to consider when upgrading a bicycle part is, always to replace the most insufficient part.

Usually, on new bikes, these would be tires. I would advise always to choose the most suitable tire for the terrain you are riding the most and make them tubeless. No question this will give you the most value possible, however, a new fork can change your bike from a mediocre one into a fully capable trail machine.

Your rides will certainly benefit the most from a better suspension. The only reason I wouldn’t value this the most is that it can cost a lot of money.

I won’t go into more details about tires and other upgrades, that would require a whole different article. If you have already decided that fork is your next upgrade then stick around and let’s see how to choose the proper one.

What Are The Best Forks?

When I’m talking about good suspensions, I like to consider only the market-leading manufacturers like Sram with their Rockshox forks, Fox forks, or some smaller but still very much competitive brand like Manitou forks. However, in terms of competitiveness on the market Manitou’s forks can be valued only in low to mid-tier suspension forks. Other than that I couldn’t talk about them as they are simply not represented nearly enough in the MTB world.

The reasoning behind taking into account only these brands is that most of the other brands haven’t even shown any tendency to improve or come up with some decent innovations for their suspensions.

Even those that tried simply failed in quality and longevity. I know that some of you might not agree with picking only these three, but that’s the realistic state of today’s bicycle suspension market.

Some manufacturers simply copy their technology but don’t let that fool you into thinking those are viable options to choose from. For the sometimes lower price, there will be some drawbacks in ride quality or durability.

Low-end Vs. High-end Mtb Fork

Both Sram and Fox have forks to suit all the possible needs.

If you have the will and time, always do the complete research. These technologies are evolving year after year and it’s way worth the time invested in research.

When upgrading within these brand’s fork ranges, you should thoroughly compare and research everything. The reason being they have so many forks that seem similar on paper but the key details can be such game-changers for different types of bikes.

Even when you see the product descriptions differentiating in only like a lower weight between low-end and high-end forks, in reality, it’s so much more than that. Lower weight always comes with better materials and even better performance.

Manitou’s forks, on the other hand, may lack some high-end tech but they offer all the same tech as Rockshox in their lower and mid-tier forks for a bit lower price. For example, I’ve been using Manitou Markhor for some time on one of my bikes. Switched to it from a crashed Rockshox Recon RL and to be completely honest, Markhor has better upper-end travel, it soaks each and every small bump on the trail better than any Rockshox in the same price range. No matter how good you adjust it.

Can You Increase Fork Travel?

Travel is the most important feature to consider when changing forks. Ideally, you should keep the same travel distance your bike came with.

You probably already know there are several commonly used suspension travel distances for all the bike types but here are the examples.

  • XC/Cross country – 100-120mm of travel
  • Trail riding – 120-140mm of travel
  • Enduro/All mountain – 150-170mm of travel
  • Downhill riding – 180-220mm of travel

There are 80mm travel suspensions which are considered cross-country suspensions but I would not consider them at all for any semi serious-serious XC riding. Your average XC trail these days is much more technically advanced than it used to be some years ago and 80mm simply isn’t enough.

Travel distance increases with the increasing technicality of trails. And while downhill trails don’t look as technical as some others at first, they require the most speed carrying through the trail. That together with the high-speed stability, requires the most suspension travel.

Increasing suspension travel means you will have some tradeoffs. First of all, the handling capacity will be greatly reduced. It will feel a lot more sluggish. The front wheel and fork are angled more in front of you and that will greatly decrease turning capability.

High travel distances impact pedaling. You are simply losing pedaling force by suspension going up and down. This means it’s much harder to pedal at high speed, and don’t let me even start about how hard is it to climb.

How Does Increasing Fork Travel Affect a Bike’s Geometry?

Now that we mentioned some tradeoffs, keep in mind that you shouldn’t even increase travel distance for more than 20mm above the factory setup.

In theory, you can do that but keep in mind that there can be some severe consequences for your bike.

The first thing you may lose is geometry. Geometry is the most important feature of any bike, period. Manufacturers spend millions of dollars developing perfect geometry for each of their bike models and it has everything to do with how easy the bike is to ride and how good it feels. Not the mention the riding efficiency, which is the most important for racers.

Increasing the suspension travel increases the fork angle and moves your seating position back. Since your bike is designed for a specific type of riding, changing its geometry won’t adapt to another category but in most cases, it will simply destroy the bike’s capabilities.

For example, If you try to make an enduro bike out of a trail bike by increasing travel by too much you will have a bike that can’t properly ride any of the two. It will become unsafe to ride, as your position and control over the bike will be severely reduced.

Any serious manufacturer will make their frames in a certain quality for any specific riding type. From cross-country to downhill frame quality gradually increases, meaning if you turn your bike into something that it isn’t supposed to be, the frame won’t be durable enough.

It can result in head tube breaking and most likely some broken bones for the rider. Not something I would ever advise anyone to do.

Most bicycle brands take away your frame warranty if you do this. I guess it’s completely reasonable on their part.

The safest option to do is buying a fork with exactly the same suspension travel. And if you really want to increase or reduce travel distance, don’t go for more than 20mm and try to keep it in the same trail category which I mentioned above.

Wheel Size

Choosing the right fork for your bike comes down to several important things to check and match first. The first and easiest is the wheel size.

There are 3 wheel sizes in today’s mountain biking.

  • 26-inch wheels
  • 27.5-inch wheels
  • 29-inch tires/28-inch wheels

Mountain bikes in recent years are slightly moving towards 29-inch tire size. 29-inch tires are actually fitted on 28-inch wheels and the 29-inch wheel doesn’t exist. However, there are some brands that manufacture wheels and name them 29-inch wheels but those are 28-inch wheels adapted for some specific 29-inch tire sizes. Just mentioning that so it doesn’t confuse you.

27.5-inch wheels are still pretty common among most bike types, while 26-inch ones are a dying breed. The advantages in bike geometry and suspension travel today mean that you can keep the same stability with bigger wheels and increase the speed at the same time. A win-win situation if you ask me.

So, there are forks specific to each wheel size and you need to buy the one that fits your wheel size. Great thing is, this won’t usually affect your choice because manufacturers usually offer the same forks for all wheel sizes.

Steerer

There are two different types of steerers. Older bikes usually had the threaded steerer which used a different headset locking system than we are used to seeing today.

If that is the steerer your bike has, consider that it probably isn’t even worth upgrading. Unless, of course, it’s a matter of sentiment and you want to upgrade it with new parts.

The non-threaded steerers are commonly used today. However, things are changing and improving here as well so you need to check on a few things.

Manufacturers developed something called tapered steerer. It’s a steerer that’s wider at the bottom. Normally, we used to have straight steerers which were 1-â…›” all the way but in recent years, trails have become more and more technical.

More technical terrain means you need to use your bike’s capabilities closer to the limit, and every mistake you make puts a pounding on your bike, especially, fork suspension. When it bottoms out in those situations, the steerer and the head tube are the only two parts that keep your bike from breaking apart.

That is when the need for a tapered steerer arose. People started breaking head tubes more often and this was an easy solution.

Why I’m explaining all this? While you can’t fit a tapered steerer in a 1-â…›” head tube, you can fit a straight steerer into the tapered head tube.

Is it a good idea? No.

A bit longer answer is that there are adapters that allow you to do this but they are not nearly as safe as they are claimed to be, nor they are effective at what you want to achieve. These adapters can never keep the 1-â…›” steerer stiff inside a tapered head tube. And that’s the whole point, stiff steerer and suspension doing all the work.

My advice is, identify which steerer your frame is made for and go with that. That way, not only you won’t do any damage, but you will end up with a much better performing bike.

How Do I Know What Headset Fits My Bike?

For each steerer type, there is a matching headset. That means if you have to change your headset because of the bearings being worn out or damaged, you will probably change the whole headset. You don’t necessarily need to, but it is recommended. 

Worn out or damaged bearings can put a lot of stress on the head screw and star nut. It’s perfectly possible to remove star nut from an old steerer and put it into a new one. However, considering it probably won’t be as stiff as a new one, you might not want to risk anything for a couple of bucks.

As a bike mechanic, I can tell you, most people damage their bikes with worn-out headsets.

So, if anything looks even a bit worn out, spend a few bucks more and change the whole headset. Be careful when choosing headsets, there are lots of complications and differences regarding frame type. You can learn more by checking one of the extensive articles on google as it is too much to explain in a few sentences. My favorite article to check up when I’m not sure which one is needed is the one from Park Tool (Park Tool).

How Do I Know What Size Axle I Need For My Bike?

It’s important that you get the fork axle that fits your front wheel hub. Be aware that some higher-end forks may not be available with all the axle variants.

Some people are forced to upgrade their wheels as well, in order to have a better fork.

Remember when I said upgrading your fork can get really expensive?

There are two most common axle types, 9mm Quick Release(QR) and thru-axle.

9mm is commonly used on low-end forks and hubs while thru-axle is much stiffer and better for front hub bearings.

While 9mm is simple, thru-axles come in several common dimensions.

The most common in my experience is 15x100mm thru-axle. It’s widely used in road cycling, and more importantly, mountain biking.

There is a 15x110mm axle as well. It’s usually called a “Boost†axle. Boost is the technology developed to strengthen wheel hubs and wheels themselves even further without turning to thicker axles.

Boost technology is a trail/enduro mountain biking replacement for 20mm thru-axles found in long-travel suspension mountain bikes, such as downhill bikes. These 20mm axles are always 20x110mm to give downhill bikes maximum stiffness.

There is a quick-release feature for thru-axles also. These are usually referred to as QR15 or QR20 so don’t let that confuse you, that’s not a standard QR which is 9mm but simply a QR system on a thru-axle.

Does Fork Offset Matter?

The offset isn’t really an issue these days, nor it necessarily ever was. The thing is 29er bikes gain a bit better handling with the 51mm offset which is referred to as G2 by some manufacturers. Mainly Trek because they were the ones to start with that.

In detail, 29-inch wheels have a longer “trail”. It’s a term that refers to the distance between the spot where the tire touches the ground and an imaginary line that goes through the head angle. The longer the trail distance is the slower turning will be.

Unlike the 46mm and similar offsets, a 51mm offset shortens the trail length and makes turning feel more like a 27.5-inch or even 26-inch wheel while keeping all the 29er benefits.

You can choose a simple path here and simply buy a fork with the same offset, but you can use this knowledge to make your turning quicker or more sluggish as well.

Some riders love sluggish steering because at high speed, especially going downhill, it gives you more stability.

Everything has its benefits.

Brake Mount

It’s really hard to find mountain bikes with v-brakes today. Disc brakes became a standard in mountain biking simply because of the stopping power they provide.

I’m afraid if you are upgrading fork suspension on a v-brake bicycle, you will have only some basic low-end forks to choose from. Forks used to feature both v-brake mount bolts and disc brake mounts but recently all the good manufacturers ditched v-brake mounts from their MTB forks.

For disc brakes, there are two mount types. The old one called I.S. mount required an adapter for every single disc brake size usually unnecessarily complicated things.

These days only post mounts are used on any decent fork. It still uses adapters but only for some disc sizes. In addition to being simpler, the mount is stiffer. How important that is with disc brakes I’m not sure but post mounts are, in my opinion, easier to adjust.

Coil vs. Air

Coil springs are usually found on lower-end suspensions while higher-end feature single or dual air springs.

Most people take away from this that air springs are better than coil springs, which isn’t true. They just behave differently and have different uses. Downhill fork suspensions, which are the pinnacle of mountain biking, mostly use coil springs.

There is a reason why low-end and downhill suspensions both use coils and that is because coils have linear compression. That simply means that coils run better on smoother terrain with less of those small bumps like small rocks, roots, etc. That also means they provide better stability, especially on jumps.

Low-end coil suspensions are usually used on everyday simple XC bikes which people use for the road as well, and that’s why coils are more than enough for them.

Unlike coil springs, air springs tend to compress more at the top and then get stiffer nearing the bottom end of their travel. This is extremely important for high speed rides with lots of small bumps because air spring will negate most of them, giving you a smoother ride. Stiffness at the bottom end prevents you from bottoming out your suspension and crashing.

I would recommend using air springs for any mountain biking except downhill. Even on everyday bikes because all the Rockshox or Fox forks have compression lockout which you can use to increase stiffness when needed. Simply said, for anything other than downhill, you get all the benefits with air springs. Not to mention, air springs are much easier to adjust for a rider’s weight.

Functions & Costs

Rebound Adjustment

The rebound adjustment is a feature you can’t ride any trail without. A rebound is the return motion after a fork has been compressed. This feature simply adjusts how fast that will happen. Different adjustments allow the suspension to better handle different types of terrain.

Trails are never the same all along, so perfect adjustment doesn’t exist. However, adjusting rebound speed can still make a fork handle bumps better.

A slow rebound will handle repeated bumps with less efficiency. A fork will often stay compressed more than it should, not giving the rebound enough time to return suspension to its starting position. Fast rebound, however, will make repeated bumps feel too bouncy and reduce your stability.

Lockout

A lockout is a feature most forks have these days. It can completely lock or make compression almost completely stiff. It’s an amazing feature for smooth parts of the trail where you can lock compression and use that to accelerate faster by pedaling.

It’s useful when riding on the road as well. But what’s most useful is a remote lockout on your handlebars. That way you can lock it while keeping a firm grip.

Personally, I love the lockout feature. Once you learn when to use it, it makes rides with variable terrain so efficient.

Compression Adjustment

Compression adjustment is similarly painful to properly adjust as rebound adjustment. Needs some experience with a specific fork/bike to learn its ways.

Though, once you get a hold of it, it’s a perfect feature to have. Since not everyone can ride the same trail at the same speed, compression adjustment lets you set the compression rate for the speed you are comfortable with.

Travel Adjustment

While the first three features are not so expensive to have, travel adjustment is found only on some high-end forks.

It’s the best feature of all, allowing you to partially turn your bike from, for example, an all-mountain bike to a trail or cross-country bike by changing the suspension travel.

How Do You Change a Fork?

To change the fork first you need to have some knowledge about how to adjust the brake. Make sure you can do it by yourself because you will have to take it off the fork.

Necessary tools to change the fork:

The first thing you need to do is take the wheel and the brake caliper off the fork. After you have taken that off, you can proceed to unscrew the stem bolts just enough to get it turning. The top cap is what actually holds the fork in the frame. Make sure the fork won’t fall down while you completely unscrew the top cap. Once the top cap is removed, keep holding the fork inside and slowly remove spacers and headset washers. Remember how they were put together. I like to place them on the table in order in which they were placed so I know exactly how to put them back later on.

Once the fork is out use a ruler to measure and mark the length of the steerer. If you are certain that’s the steerer height you want to have, you can place the Park Tool SG-8 Carbon Composite Fork Threadless Saw Guide on the marker. Proceed by cutting it at that line with Park Tool Hacksaw. Make sure you have Stanley 15-412 Carbide Grit Hacksaw Blade 12 Inch installed on your hacksaw if you are cutting a carbon steerer.

Before you can put the fork on the bike, you will need two things.

One is placing the crown race on a new fork. Unless you are changing the headset as well, you need to first take it off the old fork. I prefer doing that with a flat screwdriver instead of wasting money on special tools. It’s not that difficult to take it off. A difficult part is setting it to a new fork without damaging it. For this, you will need a Park Tool Crown Race Setting System and a hammer. Make sure to apply some Park Tool HPG-1 High-Performance Bicycle Grease on the steerer bottom part before trying to install a crown race. Now, you can slowly place the crown race on the steerer and use Park Tool Crown Race Setting System to carefully push it down and set it in place.

The other thing you need only applies to aluminum steerers, not the carbon ones. Threadless steerers need an insert that holds the headset together. In the case of a carbon steerer, it’s a compression plug that can be reused each time. However, in aluminum steerers, there is a star nut that can’t be reused, so you need a new one. Use the top cap bolt and a hammer to carefully push it into the top part of the steerer. It’s enough to place it 1/8 inch from the top. Try to get it as straight as possible, which won’t be that difficult once it’s inside because it tends to get straight by itself.

In case you are reusing the old headset and bearing, I’d suggest cleaning it all thoroughly. It’s good to use this opportunity to check if everything is in good shape. To assemble it all back you will need to grease all the contact parts on the bearing or the whole bearings in case of the open bearing type. Don’t forget to put some grease on the crown race while you are at it.

Now you can place the fork inside the headtube and put all the headset washers and spacers back in place the same way they were before. Once done with that, you will need to put the stem back on and secure the fork bearings with a top cap. Make sure you are tightening everything to the recommended tension. For that, it’s best to use a torque wrench like Venzo Bicycle Bike 1/4 Inch Driver – Torque Wrench. If everything is put in place properly, you can tighten the top cap just until the fork steerer has no play in the head tube.

Only after the top cap is tightened properly, you can tighten the stem bolts. Once again, follow the instructed torque specifications.

Now, all you need to do is put the wheel and the brake back, adjust it, and you are good to go.

Winding Up

So basically, fork suspension shouldn’t be your first upgrade, mainly because of a high price. However, it’s an upgrade that will give you the most.

You can change a mediocre hardtail bike into an amazing bike, while full suspension bikes will require you to change the shock as well.

The ability to transform your bike into something it isn’t is something to consider as well, although following some guidelines is a necessity in this case.

If you’ve done those smaller upgrades like tires, pedals, etc., a fork is definitely the next choice in line. Even before drivetrain changes.

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