Trek Rail with Fox DHX2 coil

[zaykay]

I'm beginning to have doubt's about coil shocks.

Does anyone find that the DHX2 bottoms out too easily? I have have been experimenting with different springs and still think the shock goes through the travel too fast. I'm about 87 kg fully equipped. I started with a 450 spring. That was obviously too light. So I tried the 475. And then the 500. It helped some, but it still felt like the shock had too little reserves on rough/fast stuff. So much that it made me slower. So then i tried the 550. And it still bottoms out on 70cm drops. It rides higher in it's travel and feels more composed on rougher terrain, but now some of the "smooth coil feel" starts to get away. This is very noticeable while climbing. With the softer springs, I could just sit and comfortably pedal over stuff, but now with the 550 spring it starts to feel like the air shock.

I need to experiment more with HSC/LSC, but I'm starting to wonder if I'd be better served with an X2. There might be a reason as to why the pro's don't all go coil shock.

You need to close LSC clicker more (and also HSC). I have been using same shock in Santa Cruz Nomad and due to less progressive nature of Rail’s linkage it requires a lot more damping. I have learned it works best with clickers being on the heavier damped side of Fox’s recommendation table. Also you need at least 500 spring. I’m about 6-7 kgs lighter rider and use 475 spring. I could not go any lighter and most propably could also ride 500.

 

[Doomanic]

due to less progressive nature of Rail’s linkage

Have you got the Rail linkage curve? Most Treks are progressive.

 

[Supernils]

You need to close LSC clicker more (and also HSC). I have been using same shock in Santa Cruz Nomad and due to less progressive nature of Rail’s linkage it requires a lot more damping. I have learned it works best with clickers being on the heavier damped side of Fox’s recommendation table. Also you need at least 500 spring. I’m about 6-7 kgs lighter rider and use 475 spring. I could not go any lighter and most propably could also ride 500.

Thanks for input!

If I'll have to ride with a 550 spring and a lot of damping, I would say some of the benefits of using a coil disappears.Anyway. I gave up, and am going to sell the coil. I have a X2 2021 on the way.

 

[zaykay]

Have you got the Rail linkage curve? Most Treks are progressive.

No, this is based on the feeling and knowing Slash curve. Imo compared to other manufacturers Trek’s are on middle ground usually.

 

[zaykay]

Thanks for input!

If I'll have to ride with a 550 spring and a lot of damping, I would say some of the benefits of using a coil disappears.Anyway. I gave up, and am going to sell the coil. I have a X2 2021 on the way.

If plush is what you are looking for you will find more of it with DHX2 than X2. They share the same damping circuits. Air spring will add more progression but also stiction.

Right spring with right amount of preload will feel good and damping is used for preventing bottoming. Running compression clickers more open does not necessary mean more plush ride. How it impacts depends how deep in the stroke you are. If more compression prevents blow through and helps you to stay in the first part of the linkage curve more it can be felt more plusher.

DHX2 has a lot of adjustability. After finding the right spring and preload I would keep searching. For stiffer spring you need also more rebound damping. Rail works really well with it when setup right. From both plushness and bottoming resistance point of view. I have been able to ride it in bike park and trails with more or less same clickers. In case of you happen to be from Scandinavia I rode it in Hafjell bike park last summer in Norway. You must know how fast the place is and what kind of jumps there are.

 

[Supernils]

If plush is what you are looking for you will find more of it with DHX2 than X2. They share the same damping circuits. Air spring will add more progression but also stiction.

Right spring with right amount of preload will feel good and damping is used for preventing bottoming. Running compression clickers more open does not necessary mean more plush ride. How it impacts depends how deep in the stroke you are. If more compression prevents blow through and helps you to stay in the first part of the linkage curve more it can be felt more plusher.

DHX2 has a lot of adjustability. After finding the right spring and preload I would keep searching. For stiffer spring you need also more rebound damping. Rail works really well with it when setup right. From both plushness and bottoming resistance point of view. I have been able to ride it in bike park and trails with more or less same clickers. In case of you happen to be from Scandinavia I rode it in Hafjell bike park last summer in Norway. You must know how fast the place is and what kind of jumps there are.

A couple of questions:
-Right preload? From what I have heard/read, you shall use as little preload as possible.
-I think you are the first person I have ever hard saying that more compression can result in a plusher ride feel. Is this your experience or just some kind of "philosophy"? I think you might be right, but only to a certain extent. With the right spring rate, a lot of HSC and LSC will result in a harsher, less plush ride.

Anyway. Got my 2021 x2 mounted up for å brief try today. It felt good! Really good.

 

[zaykay]

A couple of questions:
-Right preload? From what I have heard/read, you shall use as little preload as possible.
-I think you are the first person I have ever hard saying that more compression can result in a plusher ride feel. Is this your experience or just some kind of "philosophy"? I think you might be right, but only to a certain extent. With the right spring rate, a lot of HSC and LSC will result in a harsher, less plush ride.

Anyway. Got my 2021 x2 mounted up for å brief try today. It felt good! Really good.

About spring preload. As little as possible without spring rattle.

What comes to the adding compression damping making the suspension feel plusher in certain circumstances is common knowledge among suspension tuners.

Damping impacts to dynamic ride height. Think about adding damping make fork or shock dive/bottom less. When hitting concecutive bumps the latter ones hit bumbs deeper in the stroke if there are less damping. This is also impacted how well rebound is set (packing or not).

The more deep in the stroke you hit the bumb the faster the shock shaft travels (due to progressive linkage). Same compression setting feels harsher than in the beginning of the stroke. Same with the spring. Coil spring is linear so it’s easier to see this with air spring.

As an end result there are situations that LSC, rebound and spring have not been setup correctly and adding damping might fix the issue. Especially in the rear where setting the rebound right is harder and some riders prefer overdamped dead rebound feel (which causes packing).

Great that X2 works for you. Emtbs heavy weight lessens the impact of stiction on air spring.

 

[zaykay]

About spring preload. As little as possible without spring rattle.

What comes to the adding compression damping making the suspension feel plusher in certain circumstances is common knowledge among suspension tuners.

Damping impacts to dynamic ride height. Think about adding damping make fork or shock dive/bottom less. When hitting concecutive bumps the latter ones hit bumbs deeper in the stroke if there are less damping. This is also impacted how well rebound is set (packing or not).

The more deep in the stroke you hit the bumb the faster the shock shaft travels (due to progressive linkage). Same compression setting feels harsher than in the beginning of the stroke. Same with the spring. Coil spring is linear so it’s easier to see this with air spring.

As an end result there are situations that LSC, rebound and spring have not been setup correctly and adding damping might fix the issue. Especially in the rear where setting the rebound right is harder and some riders prefer overdamped dead rebound feel (which causes packing).

Great that X2 works for you. Emtbs heavy weight lessens the impact of stiction on air spring.

And to make myself clear. Adding compression damping for sure does not make suspension plusher on every case. Sometimes it does, many times not.

 

[Supernils]

And to make myself clear. Adding compression damping for sure does not make suspension plusher on every case. Sometimes it does, many times not.

Thanks for thorough reply. Guess I just misunderstood your first post slightly.

 

[Tpicch]

is that a 2020 or 2021? 60mm or 65mm stroke?

57.5 stroke only 2021 will work due to resivor length

 

[albertoy]

A friend has a Bomber CR in a large. Fits!

Hi, can you confirm no issues with Bomber CR on a Rail size Large? Thank you!

 

[Tpicch]

I have only experimented with fox shocks I’ve run dpx2 dhx2 coil and float x2 all are 2020 shocks but the float x2 because resivor on 2020 float hits frame 2021 is much shorter resivor

 

[runjhike]

I have only experimented with fox shocks I’ve run dpx2 dhx2 coil and float x2 all are 2020 shocks but the float x2 because resivor on 2020 float hits frame 2021 is much shorter resivor

What model and size Rail have you tried those shocks on?

 

[magic82]

Anyone know if a Rockshox super deluxe coil will fit a XL 2020 Trek Rail 9.8 ? I'm looking to upgrade over the std shock and I can get SRAM parts a little cheaper.

Thanks in advance.

View attachment 46540

Hi all, somebody could you confirm that this rear shock with 230x57,5 is OK for mail Rail 9 alluminium size L? I have doubts that the piggy hit on the frame.

 

[bluewater87]

Somewhat progressive.

trek rail linkage design

 

[Hob Nob]

Somewhat progressive.

trek rail linkage design

Yep, it does lend itself ‘better’ to an air shocks natural progression, especially if you are a harder/faster rider.

Certain coil shocks with hydraulic bottom outs are the way to go if you want to run one - I have had better results with that than a more normal coil shock, even with a progressive spring.

 

[Like a Boss]

A couple of questions:
-Right preload? From what I have heard/read, you shall use as little preload as possible.
-I think you are the first person I have ever hard saying that more compression can result in a plusher ride feel. Is this your experience or just some kind of "philosophy"? I think you might be right, but only to a certain extent. With the right spring rate, a lot of HSC and LSC will result in a harsher, less plush ride.

Anyway. Got my 2021 x2 mounted up for å brief try today. It felt good! Really good.

Hello Supernils. I bought a 2021 X2. My Rail has a trunnion re:aktiv shock. I have the bolts for the new shock, however I don’t have the spacers and pins for the shock. What part numbers do you use from Fox?

 

[Supernils]

Hello Supernils. I bought a 2021 X2. My Rail has a trunnion re:aktiv shock. I have the bolts for the new shock, however I don’t have the spacers and pins for the shock. What part numbers do you use from Fox?

I have the Rail 7, without the triunnion mount, so I could just use the same hardware. So I don't know. But someone else probably does. What is 'pins'?

 

[Stray cat]

Has someone fitted a regular Rock Super deluxe with Meg neg (or without) on a L size? Thanks

 

[Like a Boss]

I have the Rail 7, without the triunnion mount, so I could just use the same hardware. So I don't know. But someone else probably does. What is 'pins'?

Pins are what I am calling the shaft.....I understand that the top mount « pin » is 54mm, and the bottom is 40mm. Are your « pins » stainless steel or aluminum? Also, is the bottom offset (different sized spacers on either side of the shock eyelet)? What about the top mount, is that equidistant or offset?

 

[Doomanic]

The shock on the Rail is not offset.

 

[Like a Boss]

The shock on the Rail is not offset.

It would be cool
To see a photo of a pin mount (eyelet) mounted Rail shock. Trek told me that the shock is offset 10 mm toward the driveline on the bottom mount. The Rail diagrams do not show this because they don’t show the shock hardware. I can imagine this because my older Slash is offset on the lower mount. That doesn’t mean the Rail is the same (it’s not) but the they do use the same 230x57.5 shock.

 

[Doomanic]

Let me rephrase that.

The shock on my non-Trunnion Rail 7 is not offset. I am absolutely certain of this, not only because I've looked, but because I have changed the shock and had to modify the spacers which involved using a vernier.

 

[coregrind]

I bought a 2021 X2. My Rail has a trunnion re:aktiv shock. I have the bolts for the new shock, however I don’t have the spacers and pins for the shock. What part numbers do you use from Fox?

Upper: 10mm x 54mm 803-03-311
Lower: 10mm x 40mm 803-03-329

 

[Like a Boss]

Upper: 10mm x 54mm 803-03-311
Lower: 10mm x 40mm 803-03-329

Thanks coregrind. Can you say where you got them? I’m seeing discrepancies in different websites. Where did you get them, by those part numbers, and it worked?

 

[coregrind]

Thanks coregrind. Can you say where you got them? I’m seeing discrepancies in different websites. Where did you get them, by those part numbers, and it worked?

I looked at Trek diagrams and then talked to a gentleman at FOX. The part numbers above are what I ordered for the Rail and I believe these are the newest design for the hardware. There may be other part numbers out there that are for an older version of the hardware kits but are still possibly compatible.

What I found described at some online retailers was a generic statement about Trek and the lower hardware having an offset, without specifying a specific bike model. It’s easy to get confused and think the Rail has the offset similar to Fuel EX and some others, but it does not.

The upper shock axle (69mm), spacers (3mm each) and bearings (5mm each) are the same for 2020/2021 Rail and Fuel EX with the shock hardware being 10mm x 54mm.
The lower is where things get different:
• Rail shock axle (59mm), spacers (5mm each) and bearings (5mm each) require 10mm x 40mm hardware (no offset)
• Fuel EX shock axle (65mm), spacers (3mm each) and bearings (5mm each) require 10mm x 50mm with 10mm offset

 

[Like a Boss]

Thanks coregrind. Can you say where you got them? I’m seeing discrepancies in different websites. Where did you get them, by those part numbers, and it worked?
[/QUOTE

I looked at Trek diagrams and then talked to a gentleman at FOX. The part numbers above are what I ordered for the Rail and I believe these are the newest design for the hardware. There may be other part numbers out there that are for an older version of the hardware kits but are still possibly compatible.

What I found described at some online retailers was a generic statement about Trek and the lower hardware having an offset, without specifying a specific bike model. It’s easy to get confused and think the Rail has the offset similar to Fuel EX and some others, but it does not.

The upper shock axle (69mm), spacers (3mm each) and bearings (5mm each) are the same for 2020/2021 Rail and Fuel EX with the shock hardware being 10mm x 54mm.
The lower is where things get different:
• Rail shock axle (59mm), spacers (5mm each) and bearings (5mm each) require 10mm x 40mm hardware (no offset)
• Fuel EX shock axle (65mm), spacers (3mm each) and bearings (5mm each) require 10mm x 50mm with 10mm offset

Chris, you are Like a Boss. That is the most useful information I have found. Very well written. Thank you. I talked with Fox and Trek, and there is confusion all around. I ended up ordering the 10 x 54 and 10 x 40 kits from a place online that had them both in stock. I don't even know the part numbers now as the order confirmation only lists the sizes. As you probably saw, the part numbers, lengths given in mm and inches (39.88, 39.8, 40mm, etc), crush washers or no crush washers, five, seven, and nine piece kits.....it's all over the place. And with even Trek saying there is an offset on the bottom (via email and chat) shows that there is confusion on the matter. Confusion, and, a lot of these parts are out of stock. I did see where a guy on this forum said the old Rockshox hardware worked for his Rail 5 to install a Fox X2- I thought about finding that part number which is installed from the factory on Trek bikes.

There is a lot of variation in shock bushings and fits are not standard. Different shock manufacturers have different tolerances, ever so slight. I think the IGUS mounts were meant to simplify things, and reduce friction for most users. Old school guys may prefer aluminum bushings, or whatever, but I don't have a box of parts to try out. I need the bushings to simply, work.

I hope the parts I ordered to install this shock will do the job with no hassle. I had looked at a more local option and would have payed about $350 to install an Ohlins TTX coil on this bike, and that would have been a good option I think. The local guy with experience would have sorted all the shock hardware and such.

But I wanted to try air to try to get plushness, support, and some playfulness.

 

[davem85]

Hi, can you confirm no issues with Bomber CR on a Rail size Large? Thank you!

I had the same question and just pulled the trigger on a Bomber CR 230x62.5 coming from a 2020 Kenevo. Going to fit it next week and let you know if it fits. My Rail 5 is an XL but maybe this will help you anyway.

Right now I'm pretty unsure which spring to choose.
The pre installed FOX 425x2.80 is way too soft unfortunately - I'm about 265lbs fully kitted. Thinking about getting a MRP 600+ progressive spring right away. Or going cheap with a 600 or 650 Fox. Mrp 600+ is not (yet) available in Germany unfortunately - ordered directly from MRP US it's roughly 180€ shipped. That's a lot for a heavy spring.

Any ideas if these spring rates could match?
I ran the Tftuned calculator adding around 12 lbs for additional ebike weight, resulting in ~630 lbs.

 

[davem85]

First of all: In 62,5mm Marzocchi Bomber CR seems to fit (XL Rail 5 2020). I was just able to hold it side by side the stock shock - couldn't fit it unfortunately since it came with just one DU bushing installed.

And I'm a little bit confused about the stock shock mounting.
I removed the screws to get the shock out but these silver "axles" remain inside the top and bottom mounts of the shock - I think these are standard bushings between "axle" and shock mount but they won't rotate or move.

I think I have to reuse these since I couldn't find any Fox mounting kit with 54mm (total width for top mount).

A completely new Bomber CR obviously comes with those new Fox plastic bushings, so I thought to remove the single Du-bush and fit both top and bottom mount with these new bushings. There are complete mounting kits from Fox though but I neither know if I need this nor am I able to find it with correct size.

What am I missing here?
First time fitting a new shock - slightly frustrating.

Little help would be much appreciated ?.

 

[coregrind]

And I'm a little bit confused about the stock shock mounting.

What am I missing here?

You either need to completely remove and reuse the hardware, including eyelet bushings, from the stock RockShox shock or purchase new kits from FOX for the Bomber CR. If you’re looking to source the FOX kits, the following parts numbers might be useful:

• Upper: 10mm x 54mm 803-03-311
• Lower: 10mm x 40mm 803-03-329

I’d suggest fitting the Bomber CR first without spring so it can be fully compressed with ease, to confirm proper clearance between the piggyback and the downtube. My feeling is there will be contact prior to full compression, but that is only a guess.