HD + CCDB = Bliss?
So I just picked up a new HD frame. The frame came with a CCDB (Cane Creek Double Barrel) and I'd like to use it before trying out an air shock.
I've heard good things about how the shock will perform on the HD, but I was wondering about spring length. Do I go with one of the 2.5" stroke springs from CC or should I go a little bit longer and try the 2.75" stroke to give me more spring for preload.
I haven't really used a coil shock on my bikes, always really run air. I know the weight spring I need from tfttuning just not quite the stroke.
Thanks for the help!
Get the correct length and talk to CC about their recommendation for spring rate. Preload only sets sag the spring rate is what makes it firmer throughout the whole travel.
That's exactly what I'm asking. The stroke listed is 2.5 for the HD, should I go with a 2.5 spring, or should I go with 2.75 for having more wiggle room on setting sag? I know what the spring rate needs to be.
Originally Posted by canuck_tacoma
You won't have more wiggle room if you go longer....you will just start with more pre-load by cramming the longer spring in there.
Go for same size or if not available , one size up ie 2.75. I have a RS Vivid and I could be wrong but I don't think they do a 2.5 stroke and so I needed a 2.75. You won't preload it any more ( I had a 3.0 stroke spring on the vivid whilst I was settling on spring rate)
2.5 inch for HD160, unless a Fox coil
A 2.5 length coil for the HD160 from nearly all brands leaves enough compressed coil wind gap for 6 or so turns of preload.
Except if it is a Fox coil. Fox labels the length to coil-bind, where the coil wire bottoms on itself, and requires a longer labeled length. A Fox 2.75 coil gives 6 turns before the coil binds at 2.5 inches.
For a suspenion designed ideally for coil, including the HD, an ideal coil weight requires 1 to 2 turns preload to rebound completely to top out without harshness when unloaded with well tuned rebound damping. If no preload is working better than 1 turn preload, then a softer coil with more preload will preform better. If you need more than 3 or 4 turns preload, a firmer coil may work better. More than 4 or 5 turns preload could cause internal shock damage at top out. Each coil weight or preload change usually requires tweaking damping adjusters to balance the load or coil rate change.
Bikes designed specifically for air shocks, including the Mojo SL, when used with coil prefer 3 to 4 turns preload as a compromise to reduce mid stroke compression support for it's air spring rate design. Unlike the Mojo SL, the HD suspension leverage is ideal for a coil shock, according to a top mountain bike shock tuning expert, Darren at Push Industries.
I've found the TF Tuned recommendations too firm for tail use with smaller jumps included. (TF Tuned Shox - Spring Calculator) Especially in the shorter stoke 2.0 recommendations on my HD. The CCDB recommendations are very close to what I've used for Fox shocks on the Mojo C/SL and HD. I haven't had the opportunity to tune a CCDB, so I can't compare if they are recommended too firm also.
Buy steel coils at first until satisfied with the coil weight before spending 5 to 10 times as much per coil for a titanium coil. With a titanium coil the shock weight is very near an air shock. Although while riding, the near 1/2 to 3/4 pound added weight of a steel coil is not noticeable compared to ti or air. What is very noticeable is the downhill traction difference and usable rear braking power and modulation of a well tuned coil over air, both shocks otherwise having similar damping adjustments and quality.
That's pretty much exactly what I was looking for.
Thanks for the great answers!
When I spoke to Cane Creek about using the coil for the Mojo HD, they didn't recommend it due to the leverage ratio and said to get the DB- Air instead.
Hmm from everything I've seen (including a few coil HD's here) I'm not 100% sure about that. The HD is very friendly to coils from what I understand.
Originally Posted by mbikerguy
Well I have the CCDB and not the air so I'll give it a shot and see what happens! Can't hurt heh.
Originally Posted by monty797
Ibis Mojo HD's lack of coil shock option explained | Bike Intelligencer
Most of the shortcomings of air shocks have been overcome in the last few years and if you want to make a lightweight frame or bike, they save a lot of weight. The spring curve is different than a coil, so the suspension on the HD is designed with that air spring curve in mind.”
Their website now states:
With the advent of the new Fox RC4 coil rear shock, we've revised our stance on coil. The late stroke (bottom-out) knob enables a progressive end to the travel, perfect for the HD
Mojo HD | Bikes | Ibis Cycles US
Most coil shocks have air or nitrogen gas assisted bottom travel support, having a rising rate effect. The highest end coil and some air shocks such as the Fox RC4 and X-Fusion Vector HLR coil (and air), have adjustable oil reserve chamber internal floating piston air pressure and air chamber volume to adjust the bottom travel ramp up.
Originally Posted by mbikerguy
The CCDB coil, and Rockshox Vivid coil, unlike all other mountain bike shocks use a low pressure two-way damper fluid flow design. No gas pressure could possibly work except there is some variable fluid expansion from heat, which needs a reserve chamber with a low pressure gas chamber to allow for the increased fluid volume when heated. The damper oil reverses direction transitioning between compression and rebound. The displaced oil during compression is routed through remote dampers to the rebound side of the main piston. All damping except extreme big hit main piston blowoff, is done in the remote reserve chamber high flow dampers having a long range of fine tune damper adjustability.
The HD has a rising rate suspension leverage according to a leading custom shock tuner, Darren, the owner of PUSH Industries. So having rising rate suspension leverage the HD should work very well with the CCDB and a well balanced coil, using the High Speed Compression adjuster to fine tune the limit of bigger hit bottom travel without using an overly firm coil which would ruin the majority of lighter hits during a ride. If you search the Ibis forum, the reviews of the similar designed Rockshox Vivid coil on the HD are all very good to rave.
Personally I have recently bought the X-Fusion Vector HLR coil, due to it having all rave reviews, the few reviews there are, and because it has trailside accessible externally adjustable air assisted bottom travel. I will soon post an in depth review. My first few rides have been on slower tight twisty singletrack and some very steep slower downhill where really big hits at faster ride speed are not included. The Vector is currently set with the lowest pressure bottom assist, and has not bottomed yet, including a few 3 foot to near flat landing jumps, using a 50# softer coil than my Push tuned Fox coil required on my HD. This indicates the rising rate leverage of the HD is working well and the X-Fusion HSC damping is superb.