Coil shock in Mojo Carbon frame?
I see that the Mojo Carbon comes with an optional DHX air shock, and the frame looks pretty roomy around the shock. What I'm interested to know is if there's room for a DHX Coil or perhaps a Vanilla RC (if I can find one) in there. Has anyone tried this?
Plenty of room for a DHX Coil. Although the earlier RC is lighter and may have a softer compression range than the DHX can adjust to. And I'm not sure but I think the pre-propedal Vanilla-R before the 2004 model is set internally with the minimum compression setting of the RC. I'm trying to find an early RC to compare.
I started with the OEM air setup to see if I liked the new air shocks after 5 years on coil suspension, The Mojo rides very well, better than any other bike I've ridden with air or coil, but I have gone to coil for an even more refined and full travel ride.
I like coil for the most smooth and buttery ride, better fine-tuning, and more usable travel. I'm using a Nixon Elite (140mm travel), and '02 Vanilla-R, and they added 1 lb. to the fork over the OEM Float RL, and .6 lb. to the shock weight over the OEM RP23.
I could get a ti coil and drop .3 lb. in the rear, and a Vanilla RLC 140 is .5 pound lighter than the Nixon, for a net of 1 pound more than air.
Here's an accurate coil spring calculator:
I found this very accurate to calculate the coil on the Mojo I ended up most happy with after trying 4 different coil weights. It was also perfectly accurate for my Intense Tracer Iíve run coil on for 5 years.
I was able to return 2 coils to Fox after finding them too soft on the Mojo. I kept a second coil 50# heavier than the one I'm happy with in case I want a more heavy-duty spring later. They were $25 each plus shipping direct from Fox.
Here's another calculator:
I've found this second calculator recommends springs about 100 - 150# heavier than what I like on both my coil sprung bikes. Maybe is skewed towards very heavy-duty downhill or huge jump use. I'm all around endurance and difficult trail riding oriented. But there's lots of good information on the site too.
Derby, can I ask why you went with an old Vanilla without any platform over a new DHX Coil with pro-pedal adjustment?
After 3 weeks I finally got to test my own Ibis Mojo Carbon and itís genuine state-of-the-art dw-Link suspension with coil springs. Iíve actually waited almost 4 years since my first very impressive ride on a dw-Link designed Iron Horse Hollowpoint and later the MKiii, and Independant Fabrications and of course the Mojo versions of the dw-Link all with air shocks, to really feel the true nature of the design with coil. And the wait was worth it!
Not that the Mojo rides poorly with air at all, itís the best riding air suspended bike in the world. And many riders prefer the mid travel plushness of air springs, especially lighter weight riders. Air shocks can now be tuned to emulate the quality of coil in many ways using a small amount of low speed and moderate amount of higher speed compression damping to slow the nature of air to blow through mid travel and otherwise require firm rebound to avoid an unstable and bouncy ride.
Fox found a new 2002 Vanilla-R in their inventory, which I bought. I mounted my barely used Nixon Elite with firm spring for my weight. And tried a few springs on the Vanilla-R until I found one that optimized in balance evenly in static sag and deeper travel compression with the rate of the fork when bouncing the bike while standing on the pedals. For my 200 pounds plus ride gear, I found a 600 lb coil allowed me to use 2 turns preload for 25% sag and a steeper climbing and tight trail handling ride and best pedaling clearance, or no preload for about 30% sag and a slinkier lower and slightly softer handling ride. I my eventually ether convert my OEM Float-RL fork to Vanilla-R (for $105 in left side parts. Or sell it and get a Vanilla RLC fork for more fine-tuning options. Honestly, even with coil the new Nixon has more stiction than the new OEM Float-RL, although the linear travel handling of the Nixon and full 5+ inches of usable travel is far superior to the í07 Floatís rapid dive and usable travel limit of 4.5 inches. If the Nixon doesnít break in to eliminate stiction, a Vanilla type fork will replace it.
My bike now weighs 30.3 lbs on the same digital scale it weighed 28.5 with the OEM Float RL and RP23. The Nixon added 1 lb. over the 4 lb. OEM Float RL and the Vanilla-R coil added .8 lb. over the RP23. A titanium rear spring could reduce the rear coil gain by almost a half pound to about .4 lb. over the RP23 weight, and a Vanilla fork is .5 lb. lighter than the Nixon, so the potential is .9 lb weight cost of coil going full bling.
Before my first ride on the coil set up I planned to mount up the air fork and DHX Air again for a ride afterwards to see if the extra 1.8 lbs. more weight for the coil set up was worth it.
The bumpy typically poor condition Marin back street climb up to the trail head wasnít that impressive for being much smoother than the DHX Air, but noticeably smoother than the RP23. Climbing up to Tamarancho on the washed out pot holed Alchemy Trail didnít impress me as much smoother either, but it was buttery smooth and there was a lot better pedal clearance, I could never find a way to use enough air for less than 30% sag to gain pedal clearance with the OEM air fork and shock without suffering a rather firm and choppy ride.
Once up and turning left for the easier way around on the loop trail and speed increased the extra smoothness and more stable handling really stood out. Reaching the Serpentine Trail open meadow downhill section near center camp brought some faster speed, a 3-foot air drop to flat and, a set of very choppy deep potholes. The bike felt like it was glued to the trail, the rutted drop landing was never so smooth, even the potholes had some rhythm at the higher speed I was able to confidently carry. Later in the trail all the sharper rocky sections were made into roller coaster rhythm sections rather than the dicey and choppy handling of the air sprung ride. The bike did feel a little heavier when climbing, but I was also rather tired when I started, and I climbed as fast as I had with air.
I decided after this one ride that there was no reason to try the air sprung set up again.
Pedal bob? With the softly damped coil suspension and while seated and pedaling on flat or while climbing on pavement the dw-Link moved or bobbed about 1/8 inch shock travel translating to about 1/4 to 1/2 inch of suspension travel bob. With air optimized with no propedal compression the bob was less to almost none. But no other suspension in existence with 5.5 inches travel set with the softest damping and no platform bobís nearly as little as the dw-Link, including VPP. An ICT design bike or a same pedaling effect low-monopivot with only 4 inch travel bobís over 1 inch in the same seated pedaling conditions without using firmly set platform and damping. Yet the dw-Link complies to bumps as smoothly as a low monopivot set up with the same soft damped shock, and pedals even smoother with even greater compliance in bumps.
The coil ride is noticeably smoother and more linear. Coil eliminates the dicey and skipping feel of air suspension when descending fast in rock gardens, the ride through irregular rocks turns into a flowing watery like ride, bringing much confidence to lean into line adjustments and brake hard at the last moment. Coil ramps ups in compression resistance a little earlier in mid travel, leaving the more plush last third of deep travel used on moderate to bigger hits and g-outs. There is far less fork dive with the linear coil compression when braking lightly to moderately for handling tight line changes. Much less compression damping is required for stability, and there is less seal stiction, together resulting in velvety smooth surface feel over any terrain. The best air suspension cannot match the handling quality and smoothness of coil.
Update: Just priced a RCS titatium coil at $250 retail and they aren't made for the Vanilla-R. A larger DHX fit would have to be adapted with plate spacers or larger custom plates (adding weight). So not worth the 1/3 pound savings!
I am thinking to get a coil rear shock to complement my Mojo for certain situations. Mostly I am very happy with the Fox RP23 but am planning a 3-4 week whistler/squamish/pembarton trip and having a coil shock for Whistler and trails like River Runs Through it is very appealing.
I was thinking to get to a situation where I swap out the RP23 for a coil shock for All-Mountain stuff until I am mentally fully switched over to the coil/weight option. For most of my riding in Colorado the RP23 is perfect.
So I guess it comes down to - Of all the coil shock options out there - which one is best suited to the Mojo in an All-Mountain situation.
I like a very smooth and stable ride. The dw-Link and the Mojoís frame geometry is stable without needing extra compression damping. Medium rebound damping stabilizes any wallow from bumps and I prefer slight pack-down of the rear suspension at higher speeds than I can pedal.
The older Vanilla-R and RC (pre-2004) without Propedal are softer compressing than the DHX Coil (or Air).
With my 2002 Vanilla-R there is minimal bob when seated pedaling and a little more when standing. Thereís less bob than any other, including VPP with the same shock, climbing seated or standing on smooth pavement. And thereís no stiffening when pedaling or braking through bumps.
Propedal with the DHX Coil would totally eliminate any residual bob and still blow off for medium hits and bigger, but at the cost of smaller bump compliance and some momentum loss when pedaling through rough.
The dw-Link is very efficient without Propedal low speed damping or platform lockouts.
Using Propedal and/or firmer higher-speed compression on a dw-Link would be more for a personally preferred trail surface feel when coasting and handling corners, or bottom-out control for landing jumps, not for improving pedaling efficiency. In fact pedaling efficiency through rough terrain is reduced using firmer compression due to less compliance and increased momentum resistance.
Originally Posted by Dazed
According to Tom at Ibis, the DW link is designed to ramp the opposite of progressive, it actually ramps down at the end of the stroke. Using an Air shock that is progressive and ramps up at the end of the travel actually negates the linkage's reverse progression to give you a linear spring rate on a progressive air shock. He said you could run a coil spring, but theoretically it shouldn't ride as well as an air shock.
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The dw-Link is mildly progressive in shock travel vs. wheel travel. (Maybe I can find the analysis graphics later). The rate range is from 2.8 wheel to 1 inch shock, to 2.4/1, from top to bottom of travel.
Most other rear suspension shock linkage rate is more progressive in rate such as 3/1 to 2/1 (easier in bump compliance in mid-travel). But not all are rising in rate, such as the Yeti 575 and Santa Cruz Heckler are falling rate producing firmer pedaling with bigger hit plushness.
Overall the dw-Link is the closest to linear of any suspension available, somewhat of a middle ground between the common designs.
It depends on the effects you are looking for. I've tested the RP3, DHX 5.0 Air and non-propedal Vanilla-R, and the Vanilla-R performs best for utilizing full travel without setting excessive sag, and it's noticeably smoother and flows better over small to medium bump hits than the air shocks. The DHX Air set as smooth and soft compressing possible is nearly the same feel hitting medium and larger bumps as the Vanilla-R but not as smooth and flowing over the small to medium bump range. The RP23 is firmer feeling every where, an excellent XC racing shock.
I'm a clydesdale (250lb on the nose) and I'm told I'd benefit a lot from a coil shock over the RP3. Right now, with the RP3 at it's top-most specified pressure, the rear sags a bit too much (the 35-40% range) and I can't adjust the ride to the feel I like...
Can anyone make recommendations as to which coil shock to get, and what coil size with that shock?
More info: I ride XC, enjoy technical uphill as much as downhill, and pick lines rather than just bomb. I try to be as light on my feet as is possible for someone my size, and I can't see myself weighing anything less than 225 because of my height and frame. I don't really break stuff, so I'm looking for a shock that handles my weight as it should.
I'd appreciate any specifics. The Fox site is appalling, and I'm new to full suspension so it's all greek right now, and I need to pick something now if the LBS will do a swap/exchange.
I would be interested in Coil shock recommendations as well.
Originally Posted by schnee
As far as the spring rate, the link Derby gave above should be able to answer your questions. The stroke length is 2"
PARAMETER VALUE UNIT
RIDER WEIGHT (WITH GEAR) 250lbs
DAMPER STROKE 2"
WHEEL TRAVEL 140mm
DESIRED SAG % 25%
WEIGHT DISTRIBUTION (% REAR / % FRONT)
RELEVANT SHARE OF BIKE WEIGHT %
SPRING RATE 800 (140) lbs/inch (N/mm)
PRELOAD 1 turn
CALCULATED SAG 26 (0.51,13) % (in,mm)
SPRING RATE 750 (131) lbs/inch (N/mm)
PRELOAD 2 turns
CALCULATED SAG 25 (0.5,12.7) % (in,mm)
SPRING RATE 700 (123) lbs/inch (N/mm)
PRELOAD 3 turns
CALCULATED SAG 25 (0.49,12.5) % (in,mm)
SPRING RATE 650 (114) lbs/inch (N/mm)
PRELOAD 4 turns
CALCULATED SAG 25 (0.49,12.5) % (in,mm)
preload is measured from where the plate first engages the spring.
little preload means:
* supple at beginning of stroke
* solid in middle stroke
* better bottom out protection
high preload means:
* may be harsh at beginning of stroke
* supple in middle stroke
* may bottom due to lower spring rate
Coil usually requires some trial and error to get the right spring as well as adjusting the damping to match the spring.
Originally Posted by schnee
Go as light in spring weight as you can that will prevent bottoming any more often than occasionally on your regular rides, also one that will produce a static sag that you want, 25 - 30% for the Mojo (25% is a little better for climbing angle and pedal clearance). Go to the next higher weight of spring if you need more than 3 turns spring preload. I'm using 2.75 turns preload to run a spring soft enough to obtain full travel and have about 27% sag), your set up will probably be different. Coil is much more fine tunable than air.
I found the link I posted above in this thread very accurate for spring selection.
If your bike shop will swap out, then the new Fox Van-R should be sufficient or the DHX Coil for a wider range of adjustment.
Or you can probably find a new or barely used Fox Vanilla-R coil shock on ebay or the MTBR classifieds for no more than $100, perhaps much less.
Fox sells springs direct from Customer Service for $25 - $30 plus shipping. Use the spring calculator and buy one on the softer end of the range and one at the firmer end of the calculated suggestion. When you order from Fox or bike shop ask if you can return the spring(s) you can't use in clean unused condition.
Test each spring on pavement to keep it clean for returning. First measure your static sag while seated in your riding position and not moving and adjust preload to get sag to about 25% or where you want it. You can slide the rubber bump stop up the shock shaft to see how much it moves when you put weight on the bike. And with compression damping set full soft (if there is a compression adjustment dial - The older Vanilla-R or new Van-R has just a rebound adjuster) try to bottom it by pounding your weight on the seat while riding up hill. You can also slide the rubber bump stop up the shaft to see how close it gets to bottoming. You'll be right if you don't see any space below the bumper and don't feel any harsh bottom out, and your sag is where you want it.
Awesome advice, thanks. I appreciate the detail. :-)