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Discussion Starter · #1 ·
Hello! This will be my first post.

I have in my possession a borrowed Marzocchi Bomber CR, and a Trek Re:Aktiv shock both of which fit the bike. I'm having a hard time finding the leverage curve for this bike, but I understand it to be approximately 3.0 at the beginning of stroke, and 2.5 towards the end. My weight is 220 with gear, and using a 600lbf coil puts me at roughly 20% sag.

I've already decided I want to send it to Avalanche for a tune end of next season, and after having chatted with Craig, It seems like the damping can be dramatically improved on both of these shocks. ie: the re:aktiv shock can become more plush, and the bomber can actually be made more progressive via the bottom out and speed sensitive damper.

Craig also advised against a progressive spring, since preload takes up too much of the early stroke, and the firm rate affects the midstroke too soon.

Here's my issue. I can't decide. I really, really like the feel of the coil, but I bottom out like all the time on rougher trails On the other hand, if the air-can can be made to feel as plush as the coil, I've no need to go out and buy a Bomber of my own.

I ride mostly trails, I like both fast & flowy and technical trails. I tend to avoid big drops, but I want to hit the odd drop/jump as I progress. I want to hit more all-mountain stuff. Climbing is harder with the coil, but I've never had so much grip in my life and I think I'm in love, so I think I can get past it.

I feel the need to talk this out, but there's no one in my circle who understands this, and I think I've spent enough of Craig's time. I'm only just learning about leverage curves & the finer points of damping.

One of the point I want to figure out is where thus bike fits in the linear to progressive spectrum. Am I better off tuning the air-can until I can afford a frame with more progressive geo and then tune the bomber? Or can I really get away with the tapered bottom out on my current frame?

Can someone talk some sense into me?
 

· Elitest thrill junkie
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Hello! This will be my first post.

I have in my possession a borrowed Marzocchi Bomber CR, and a Trek Re:Aktiv shock both of which fit the bike. I'm having a hard time finding the leverage curve for this bike, but I understand it to be approximately 3.0 at the beginning of stroke, and 2.5 towards the end. My weight is 220 with gear, and using a 600lbf coil puts me at roughly 20% sag.

I've already decided I want to send it to Avalanche for a tune end of next season, and after having chatted with Craig, It seems like the damping can be dramatically improved on both of these shocks. ie: the re:aktiv shock can become more plush, and the bomber can actually be made more progressive via the bottom out and speed sensitive damper.

Craig also advised against a progressive spring, since preload takes up too much of the early stroke, and the firm rate affects the midstroke too soon.

Here's my issue. I can't decide. I really, really like the feel of the coil, but I bottom out like all the time on rougher trails On the other hand, if the air-can can be made to feel as plush as the coil, I've no need to go out and buy a Bomber of my own.

I ride mostly trails, I like both fast & flowy and technical trails. I tend to avoid big drops, but I want to hit the odd drop/jump as I progress. I want to hit more all-mountain stuff. Climbing is harder with the coil, but I've never had so much grip in my life and I think I'm in love, so I think I can get past it.

I feel the need to talk this out, but there's no one in my circle who understands this, and I think I've spent enough of Craig's time. I'm only just learning about leverage curves & the finer points of damping.

One of the point I want to figure out is where thus bike fits in the linear to progressive spectrum. Am I better off tuning the air-can until I can afford a frame with more progressive geo and then tune the bomber? Or can I really get away with the tapered bottom out on my current frame?

Can someone talk some sense into me?
From what I understand having talked to him and with other bikes, you want at least around 20% progression in the bike to be considering a coil shock (and more like 25-30 for real DH stuff), even with the bottom out protection. While it's theoretically possible to put such a shock on a bike that is less progressive, then you are starting to roll the dice, it'll will be ok right up until the time when it isn't and slams into the frame under a real hard bottom event. Damaging the frame and shock is a real possibility. As you work back from that 20% progression, the chances of this increase and increase. You can get an air shock to perform much better with good tuning...but it still won't feel like a coil shock. Still, there is definitely room for improvement. Best thing to do is buy your bike with the intention of a coil, making sure it is progressive enough to support one.
 

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Discussion Starter · #4 ·
From what I understand having talked to him and with other bikes, you want at least around 20% progression in the bike to be considering a coil shock (and more like 25-30 for real DH stuff), even with the bottom out protection. While it's theoretically possible to put such a shock on a bike that is less progressive, then you are starting to roll the dice, it'll will be ok right up until the time when it isn't and slams into the frame under a real hard bottom event. Damaging the frame and shock is a real possibility. As you work back from that 20% progression, the chances of this increase and increase. You can get an air shock to perform much better with good tuning...but it still won't feel like a coil shock. Still, there is definitely room for improvement. Best thing to do is buy your bike with the intention of a coil, making sure it is progressive enough to support one.
It seems like all 130mm bikes are shipped with a can. Supposing I get a new frame with a very progressive curve and roughly 130/140 mm rear travel, which frame(s) should I be looking at?
 

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Discussion Starter · #6 ·
I think that's more about weight and ease of setup rather than problems with using a coil.
Right, but my understanding is frames are usually designed harmoniously around shocks. That it comes with a can strongly suggests a less progressive geo, as part of the progressiveness the designer wants come from the air can.

I'm certain some of those frames are progressive enough for a coil, but it's hard to telp which ones.
 

· Elitest thrill junkie
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I think that's more about weight and ease of setup rather than problems with using a coil.
No, it's largely about what the manufacturer designed their bike around and that in turn was due to ease of manufacturing air, vs. having to get/have all sorts of coil spring lengths and weights for the various bikes. You can design a bike to work ok with both, but ok isn't great and generally if it comes with an air shock, it was designed for an air shock.
 
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A few things -

You are going to get a lot of wildly conflicting opinions on here, so if you have chosen a tuner I would lean towards whatever they are recommending, otherwise what’s the point in using them?

The treks go well with a coil shock, with an appropriate spring and suitable damping you shouldn’t have as much trouble with bottoming out. Personally I like the progressive springs, but a well designed bumper of the right firmness should also do a decent job.

Did you try the linkage design blog? That should have the leverage info your after. You will need google translate on! I can’t recall the exact numbers but it’s likely a progressive-linear type so as long as you have some form of bottoming protection ( eg a better bumper) it will go nicely. There’s slightly more too it than just the % of rising rate, as a frame could have a similar % but be more regressive-progressive which on the trail would feel more wallowy and harsh with more sudden changes in rate.
 

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Discussion Starter · #9 ·
Thanks everyone for your answers. I think I'm just going to get both tuned and do a proper comparison.
I took a peek at the linkage blog, and the Canfield Bikes Lithium 2021 uses a coil and is less progressive than the fuel. I think with the proper spring, damping & bumper, like. You mentioned Johnny, it'll be alright.
 
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