Mountain Bike Reviews Forum banner
1 - 20 of 32 Posts

·
Registered
Joined
·
367 Posts
Discussion Starter · #1 ·
For anybody who ever thought the SB would be better with a coil over I thought I'd post my modification. Titus says the SB has a falling rate to match progressive air shocks and that a coil over will not work. I analyzed the linkage and found that to be a crock of [email protected]#$, at least for the TALAS equipped frame. I found the TALAS equipped frame to be full rising rate and decided to go for it with a coil over. I'm not sure if this would work with a standard SB.

Anyway, there are a number of constraints and considerations: Check out the photos below

1. The stock TALAS I2I is 8.25 in. but neither Fox nor anybody else to my knowledge make a coil over in that configuration. The nearest I could find is the 7.875 x 2.0 stroke Fox Vanilla R (or RL). However just fitting this shock to the existing mounting holes slackens the angles about a degree and results in swing link/seatstay interference just before full compression.

2. So...I had to find a suitable mounting location on the swing link at the 7.875 I2I while maintaining the geomtetry. Further, this new location could not result in any intereferences between the mounting hardware and the pocketed CNC'd truss structure of the swing link. Fortunately there is just such a spot, but only if you use a 6mm SHCS as opposed to the stock 8 mm SHCS. I carefully marked the spot with a caliper and drilled it on a drill press. This spot just allows the head of the 6mm SHCS to sit within the truss structure. The dimension across the corners of a standard 6 mm nylock nut just barely interfere with the truss structure of the swing link so I fabricated some washers with tiny diameter to shim the nut just outbaord of the truss.

3. This also means you have to fabircate or purchase a new eyelet reducer. These can be had from Fox but personally I think the two piece reducers suck. They result in the bushing wearing out in mere months vs almost a year with a 1-piece reducer. I purchased a .5" aluminum reducer from McMaster Carr, cut it to length, and bored it slightly with a drill to accomodate the 6mm SHCS. I could thus still use the collars from the one piece reducer kit Titus sells aftermarket.

4. You can see that the dimension of the coil over fits fine. No interferences. The leverage and motion ratios are essentially maintained. The effective lever arm on the swing link does shift from about 3.1 to about 3.2 inch so maybe I'm getting 5.5 inch of travel vs the stock 5.6/5.7 but the responsiveness more than makes up for it.

5. OK, enough of the techie stuff...how does it ride? GREAT. I was coming from a coil over Intense Uzzi and was longing for the small bump response of a coil over. The TALAS rear is the best feeling air shock I've come across but still couldn't match that of a coil over. This modification really brings the Switchblade to the next level. The suspension is very linear/slightly rising rate. I run a relatively soft 400 lb spring for my 180 lb and never incurr any harsh bottom out, even on 5+' drops.

6. I've been riding this setup for 2+ months now with 0 problems. The wall thickness where you drill through is still very substantial (.250"+) and more than sufficient to carry the compressive loads of the shock. The 6mm SHCS is also sufficient. The Intense Uzzi ran a 6mm with about a 4" span vs the 1.5" of the SB and didn't bend.

I like having a one off but would recommend this mod to anybody with basic fabrication skills and a desire for yet more supple suspension.
 

Attachments

·
Registered
Joined
·
286 Posts
Awesome mod.

I am currently riding a switchblade talus frame. I was wondering what kind of sag and rebound settings were you running on your talus shock. I have had mine a while and I was trying to see if people are running a full half inch of sag. This is what titus tells you. I agree about the leverge ratio definately a rising rate probably to save the frames from damage and save titus on warranty issues. Any info would be appriciated.
 

·
Registered
Joined
·
367 Posts
Discussion Starter · #3 ·
3/4" sag

tom schoonveld said:
I am currently riding a switchblade talus frame. I was wondering what kind of sag and rebound settings were you running on your talus shock. I have had mine a while and I was trying to see if people are running a full half inch of sag. This is what titus tells you. I agree about the leverge ratio definately a rising rate probably to save the frames from damage and save titus on warranty issues. Any info would be appriciated.
I was running about .75" sag vs the recommended .5" but then I'm after a cush ride over the small high frequency stuff. I still didn't encounter any harsh bottom out unless I was doing bigger drops. As to rebound, just enough to keep the rebound under control (not too fast, not too slow). Not sure of # of turns.
 

·
Do It Yourself
Joined
·
5,720 Posts
I would seriously think about getting the 5.25" rockers that's made for the 7.87" shock. Second, to avoid any problems you might think about a progressive coil shock (Romic, 5th or Swinger) or possibly sending the Vanilla to Push. Push can add extra ramp up by adjusting the bottom out bumper size to get what you need as well as get rid of that problematic lockout.
 

·
Registered
Joined
·
367 Posts
Discussion Starter · #7 ·
Homebrew said:
I would seriously think about getting the 5.25" rockers that's made for the 7.87" shock. Second, to avoid any problems you might think about a progressive coil shock (Romic, 5th or Swinger) or possibly sending the Vanilla to Push. Push can add extra ramp up by adjusting the bottom out bumper size to get what you need as well as get rid of that problematic lockout.
The 5 or 5.25" rockers would be ideal but I wanted more than 5.25" travel. The extra .25" may not seem worth it to a lot of folks but I certainly notice the difference between 5" and 5.5" travel. For the riding I do here in So Cal, 5.5 is the magic number...any less is too little for the rough stuff and any more gets too soft for death march climbs. I had customized my Intense Uzzi previously so I've been riding 5.5 travel now for 7 years.

As to bottom out and problematic lock out, I've had neither problem. The 5.7 linkage is rising rate so a coil over does not have any bottoming issues. I'm not a fan of the prgressive shocks anyway, I find they compromise on high speed small amplitude responsivness due to the higher compression damping.
 

·
Registered
Joined
·
804 Posts
Rising / Falling rate

I have been curious as to whether or not the SB is in fact a falling rate design. I did some quick calculations, looking at the suspension movement at the first 1/4 inch and the last 1/4 inch and it did seem to indicate that the SB in fact does have a rising rate suspension design.

I then did some searching and found this program, very cool:
http://www.extra.hu/linkage/

Anyways, I mapped out the SB (in 4.5" mid travel mode) and it clearly showed that it has a continually rising rate.

I also mapped out the Tracer and the results were very similar to the SB, although the Tracer was rising a bit faster.

Anyways, this indicates to me that the SB would be a good candidate for a coil shock as well.

One thing that really threw me for a loop was looking at bikes with severe FALLING rates, like the Bullit, and this bike always comes with a coil shock.

How can a Bullit, with a falling rate suspension design, use a coil shock without harsh bottoming? Do you just have to rely on the bumpers?
 

·
Registered
Joined
·
1,059 Posts
Switchblade File ?

Hi there
Could I get the Switchblade file for the program ? if you dont mind
thanks

frank n. beans said:
I have been curious as to whether or not the SB is in fact a falling rate design. I did some quick calculations, looking at the suspension movement at the first 1/4 inch and the last 1/4 inch and it did seem to indicate that the SB in fact does have a rising rate suspension design.

I then did some searching and found this program, very cool:
http://www.extra.hu/linkage/

Anyways, I mapped out the SB (in 4.5" mid travel mode) and it clearly showed that it has a continually rising rate.

I also mapped out the Tracer and the results were very similar to the SB, although the Tracer was rising a bit faster.

Anyways, this indicates to me that the SB would be a good candidate for a coil shock as well.

One thing that really threw me for a loop was looking at bikes with severe FALLING rates, like the Bullit, and this bike always comes with a coil shock.

How can a Bullit, with a falling rate suspension design, use a coil shock without harsh bottoming? Do you just have to rely on the bumpers?
 

·
Registered
Joined
·
367 Posts
Discussion Starter · #10 ·
Progressive shock

frank n. beans said:
I have been curious as to whether or not the SB is in fact a falling rate design. I did some quick calculations, looking at the suspension movement at the first 1/4 inch and the last 1/4 inch and it did seem to indicate that the SB in fact does have a rising rate suspension design.

I then did some searching and found this program, very cool:
http://www.extra.hu/linkage/

Anyways, I mapped out the SB (in 4.5" mid travel mode) and it clearly showed that it has a continually rising rate.

I also mapped out the Tracer and the results were very similar to the SB, although the Tracer was rising a bit faster.

Anyways, this indicates to me that the SB would be a good candidate for a coil shock as well.

One thing that really threw me for a loop was looking at bikes with severe FALLING rates, like the Bullit, and this bike always comes with a coil shock.

How can a Bullit, with a falling rate suspension design, use a coil shock without harsh bottoming? Do you just have to rely on the bumpers?
The Bullit gets away with a regressive rate by using a progressive shock to counteract.
 

·
Registered
Joined
·
286 Posts
falling or rising rate on Id?

I have been curious about that I own a Switchblade and am in the process of trying an Id. Do you know if this design has a falling rate or rising and how would it compare to the switchblade rising rate any info would be great!
 

·
Registered
Joined
·
804 Posts
tom schoonveld said:
I have been curious about that I own a Switchblade and am in the process of trying an Id. Do you know if this design has a falling rate or rising and how would it compare to the switchblade rising rate any info would be great!
The Id looks to have a very similar rate curve to the SB. I am certainly no expert at this. I'd suggest checking out the Linkage program if you want details, you can compare them side by side that way.

What are you looking for in the Id that the SB doesn't provide? Just curious.
 

·
Tonight we ride.
Joined
·
769 Posts
frank n. beans said:
the SB in fact does have a rising rate suspension design.
I can understand how they would be concerned with running coil shocks, but you are correct that it definitely has a rising rate. This is what I got when I did my two linkages a while back:



I'm not sure if SC used them, but there are progressive rate springs out there that ramp up towards the end of compression. Doubtful if it was just a Vanilla.
 

·
Registered
Joined
·
804 Posts
What would you do?

fonseca said:
I can understand how they would be concerned with running coil shocks, but you are correct that it definitely has a rising rate.
Since you have done some analysis yourself, what are your thoughts on going coil for the SB? Would you do it, if you wanted a coil shock? Why do you think Titus is so against coil shocks on this bike? Is it really a bad design for coil, or are they just worried that people will confuse the SB for a FR bike if it has a coil?

The curves for the SB are very similar (although not quite as progressive) as the Tracer and the Truth, both of which will take a coil.

My question is centered on this: If the coil works good on the Tracer, why not the SB?

Don't get me wrong, the SB rides really nice with an air shock. However, I think coil rides better.

Thanks for your input.
 

Attachments

·
Tonight we ride.
Joined
·
769 Posts
frank n. beans said:
Since you have done some analysis yourself, what are your thoughts on going coil for the SB? Would you do it, if you wanted a coil shock? Why do you think Titus is so against coil shocks on this bike? Is it really a bad design for coil, or are they just worried that people will confuse the SB for a FR bike if it has a coil?
Personally I think coil would be perfectly fine. My warranty ran out this past June, and I have considered getting an old Vanilla RC I have pushed and running that. However, Titus is still great about covering older bikes, so if the unthinkable happened I would be SOL. So I doubt I'll ever run coil on it. I plan to get a Super-Moto when I have the cash (hmm, should I misuse some of my student loans this year? :) ). Then I will turn my SB into a pure XC bike and sell my other XC bikes.

There is a weight limit on this bike, and Titus has more overbuilt frames for coil and FR applications: I think that's the real reason they say no coil. They don't want a bunch of broken SBs being warrantied which were abused for light FR.

It's a mild progressive rate, but I really doubt I would bottom out with coil, as I am pretty careful about setting up my bike and would start with a heavier spring. But to be honest I don't have a problem with air shocks, just with the Float air shock in particular due to the excessive ramp-up at the end. That forces me to run it too soft to get more travel, which has some negative effects. I might get some spacers made for the 5.7" linkage and run an AVA sleeve, or perhaps see what 2005 brings for air shocks. I don't really want to lose tire clearance with the new 5.25" link. I like running 2.4 tires.
 

·
Registered
Joined
·
804 Posts
I am becoming more and more convinced that the "no coil on sb" rule is simply to keep people from abusing it like a FR bike.

Food for thought: The Loco Moto is a straight up falling rate design, and it (optionally) comes with a Vanilla shock.

Can a 175lb "XC" rider who picks a reasonable spring weight, and never drops anything more than handlebar height on the trail run a coil on the SB? Or should I just stop thinking about it and stick with the Float. Overall the Float has treated me well, but I really like the feel of coil. I don't mind a little extra weight. That is my dilemma.

I say XC but that does include some fast rough sections, occasional wheelie drops usually no more than 2 feet, and flowing with the trail (i.e. if the trail allows you to launch over something / into a transition, let 'er rip). I ride "light", and don't ever "go big".

Check this out: Quasi (in rising / falling config) compared to the SB. Note, the Quasi can also be set up in full rising rate depending how the rocker is positioned.

A little bit of knowledge can be dangerous in the hands of someone like me. I'm trying to gather as much input on this topic as possible to hopefully steer me towards the correct decision. Thanks for the input, it is appreciated.
 

Attachments

·
Registered
Joined
·
367 Posts
Discussion Starter · #20 ·
Go for it

I may be biased since I already did it but I'd say you're an excellent candidate for a coil over. I'm 180 lb, ride mostly as you describe but with occasional drops of about 5ft when I make trips to the Serras and the coil over treats me very well. I use a 400lb spring which nets about .63" sag. Bear in mind this is with the 5.7 TALAS linkage, 2.0 stroke shock. Coil over blows air away in performance and reliability!
 
1 - 20 of 32 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top