Sprindex allows for tool-free, easy adjustment of your coil's spring rate.

Adjusting your shock's spring rate can profoundly improve your bike's handling and suspension. In fact, you may find yourself using different spring rates for different trails, depending on the conditions and type of trail. Or you may increase your spring rate for long climbs and decrease it for down hills.

No expense was spared on the materials or manufacturing processed used. The coil itself is made of super high tensile spring steel similar to "lightweight" springs (which is why Sprindex is lighter than regular springs) in order to handle the stress of the system when adjusted to its highest spring rate setting, as well as reduce coil mass. The Sprindex assembly is made of glass reinforced polymer. The 5 included adapters are made of slippery Delrin.

Spring rate is the force required to move a spring a given distance and independent of preload. For example, a "400 lb/in" spring requires 400 pounds to move the spring 1 inch and 800 pounds to move a spring 2 inches. Preload is how much force is required to start moving the spring. Sprindex is patent pending in many countries.

Follow your shock manufacturer's instructions for preload amount and sag and other shock adjustments. Do not preload your Sprindex more than 3 turns and 1 to 2 turns is preferred.

Your Sprindex coil behaves like a regular coil that has a spring rate the same as your adjusted Sprindex spring rate. Adjusting your Sprindex does not change the length of the coil and so does not change your preload. Preload is adjusted normally and with the threaded ring that came with your shock.

 

How does Sprindex adjust spring rate?

The spring rate of a spring is the amount of force it takes to deflect the spring a certain distance (typically pounds per inch or Newtons per mm). Spring rate is a function of 4 characteristics: wire diameter, coil diameter, material, and number of active coils. More active coils causes a lower spring rate and fewer active coils causes a higher spring rate. Think of it like this: the less wire there is to bend, the stiffer the spring. By twisting the Dial, Sprindex works by altering the number of active coils available for deflection. The adjusted spring rate is displayed through a window in the Dial.

 

Coil shocks versus air shocks

Most agree that coil shocks outperform air shocks, assuming the right spring rate for the particular rider. Air shocks have significant "stiction" which is friction that resists the shock's initial movement. Coil shocks have much less stiction. Coil shocks soak up small bumps much better, better tire contact with the ground, give better traction, better ride quality, and make a rider measurably faster. So why are air shocks more common? The answer is lack of adjustability for coils and weight. Traditional coils have a fixed spring rate and spring rate has a dramatic effect on riding performance and feel. Most people ride the wrong spring rate because springs are typically only available in wide increments. Spring rate has a profound effect on bike performance. Coil shocks also weigh more than air shocks, but when using the right spring rate, the small weight penalty is easily worth it. Besides, Sprindex is lighter than ordinary shock springs.

 

Spring rate is different from preload

Coil shocks include a threaded ring for preloading the coil. However, preloading is not the same as using a stiffer (higher spring rate) spring.

Too much preload causes:

Sprindex

Preload

A sprindex coil behaves exactly like a regular coil of the selected spring rate. For example, Sprindex adjusted to 435 lb/in behaves just like a custom made 435 lb/in standard coil.

 

 

 

 

Poor small bump absorption resulting in a harsh ride and poor traction because it increases force to start coil movement.

Either reduces shock travel and/or over-stresses spring.

Improper SAG. SAG must be achieved by spring rate, not preload.

Doesn't change coil spring rate. If you bottom out with a spring, heavy preloading may not solve this and will mess up the rest of the stroke.

Mountain bike shocks are designed for as little preload as is necessary to take play out of the system. Any more preload than this harms ride performance.

 

Sprindex versus "progressive" coils

Firstly, all coil shocks are already progressive because of the rubber bumper that is contacted at the end of the stroke. The rubber bumper is itself a spring that is active between about 10 and 20% of the end of the stroke, depending on bumper thickness and stroke travel. All by itself, the rubber bumper can add over 200 pounds of force to help prevent a hard bottom out. The rubber bumper will more than double your spring rate for the last 5 to 10mm's of stroke. Ideally, you should only use your full shock travel on the very hardest hits of your ride and your spring rate should be adjusted high enough to never fully bottom out.

Shock without coil
Bumper just before being compressed towards end of stroke.

Shock without coil
Bumper compressed at end of stroke.

So called "progressive" coils have 1 or 2 coils that are spaced closer together such that they bottom out and become inactive part way through the stroke. This suddenly increases the spring rate at some point in the stroke, but this is not similar at all to Sprindex. Available progressive springs are not adjustable which causes the same problem as regular springs in that they cannot be tuned for you and your riding style. The Sprindex spring rate is finely adjustable over its range in order to provide full travel on your biggest hits and optimized performance on the small stuff. Progressive springs are an attempt to solve riding the wrong spring rate and a progressive spring that provides full travel will cause your sag to be excessive and vice versa.

 

Performance Adapters

Performance Adapters are included. Sprindex coils fit a wide variety of shocks, but you must use the Performance Adapters for most of them. Our Performance Adapters both improve the fit between the coil and your shock and are made of low friction Delrin to improve shock performance by allowing the spring to twist during high deflection. Also, the Performance Adapters help prevent the preload ring from self-adjusting due to coil windup. See bottom of Performance Adapter for instruction of which Performance Adapter you should use. For Rockshox, no Performance Adapter is required but we recommend you use the Performance Washer adapter for shock performance and to help prevent preload self-adjustment.

Sprindex is compatible with a wide variety of shocks.

There are three different Sprindex lengths and strokes available, and each Sprindex coil can be adjusted through a certain spring rate range. Be sure to use the correct included adapter as described. Make sure that the spring length fits on your shock and that your maximum shock travel is not more than the specified Sprindex coil travel.

IF YOUR SHOCK IS NOT LISTED IN THE BELOW COMPATIBILITY TABLE:

Determine what your shock's stroke is and then compare that to the available Sprindex coils. Sometimes, you can find the stroke specification on the website of your bike brand for your bike model. The stroke printed on your existing coil is a clue, but it might have more stroke than your shock actually needs. Or, just measure the stroke per the picture above. Ideally, choose the Sprindex coil that has at least the amount of stroke that your shock requires, and then measure whether that Sprindex coil overall length can fit between your shock's flanges. The Sprindex coil lengths are listed in the below compatibility table. Note that most shocks can only achieve about 5mm less than their listed stroke because the bottom-out bumper can only be compressed so far, so in most cases it is okay if the Sprindex coil has up to about 3mm less stroke than your shock's stroke rating.

Find your shock on the below table and note which Sprindex family you need.

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

Fox DHX2

230 mm

60 mm

metric

65 x142

Fox DHX2

230 mm

65 mm

metric

65 x 142

Fox DHX2

Trunnion

205mm

60mm

metric

65 x 142

Fox DHX2

Trunnion

205mm

65mm

metric

65 x 142

Fox DHX2

8.5 inch

2.5 inch

English

65 x 142

Fox DHX2

8.75 inch

2.75 inch

English

65 x 142

Fox DHX2

7.875 inch

2.0 inch

English

55 x 126

Fox DHX2

7.875 inch

2.25 inch

English

55 x 126

Fox DHX2

210 mm

50mm

metric

55 x 126

Fox DHX2

210 mm

52mm

metric

55 x 126

Fox DHX2

210 mm

55mm

metric

55 x 126

Fox DHX2

Trunnion

185mm

55mm

metric

55 x 126

Fox DHX2

9.5 inch

3 inch

English

75 x 162

Fox DHX2

Fox DHX2

Trunnion

250mm

225mm

75mm

75mm

metric

metric

75 x 162

75 x 162

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

MRP Hazzard

230 mm

65 mm

metric

65 x 142

MRP Hazzard

230 mm

60 mm

metric

65 x 142

MRP Hazzard

230 mm

57.5 mm

metric

65 x 142

MRP Hazzard

Trunnion

205 mm

65 mm

metric

65 x 142

MRP Hazzard

Trunnion

205 mm

60 mm

metric

65 x 142

MRP Hazzard

Trunnion

205 mm

57.5 mm

metric

65 x 142

MRP Hazzard

200mm

51mm

metric

55 x 126

MRP Hazzard

200mm

57mm

metric

55 x 126

MRP Hazzard

210mm

50mm

metric

55 x 126

MRP Hazzard

210mm

55mm

metric

55 x 126

MRP Hazzard

9.5 inch

3 inch

English

55 x 126

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

Marzocchi 2019 Bomber CR

230 mm

60 mm

metric

65 x 142

Marzocchi 2019 Bomber CR

230 mm

65 mm

metric

65 x 142

Marzocchi 2019 Bomber CR

Trunnion

205 mm

60 mm

metric

65 x 142

Marzocchi 2019 Bomber CR

Trunnion

205 mm

65 mm

metric

65 x 142

Marzocchi 2019 Bomber CR

7.875 inch

2.0 inch

English

55 x 126

Marzocchi 2019 Bomber CR

7.875 inch

2.25 inch

English

55 x 126

Marzocchi 2019 Bomber CR

210mm

50mm

metric

55 x 126

Marzocchi 2019 Bomber CR

210mm

55mm

metric

55 x 126

Marzocchi 2019 Bomber CR

Trunnion

185mm

52.5mm

metric

55 x 126

Marzocchi 2019 Bomber CR

Trunnion

185mm

55

metric

55 x 126

Marzocchi 2019 Bomber CR

250mm

75mm

metric

75 x 162

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

DVO Jade Coil

230 mm

65 mm

metric

65 x 142

DVO Jade Coil

230 mm

62.5 mm

metric

65 x 142

DVO Jade Coil

230 mm

60 mm

metric

65 x 142

DVO Jade Coil

230 mm

57.5 mm

metric

65 x 142

DVO Jade Coil

Trunnion

205 mm

65 mm

metric

65 x 142

DVO Jade Coil

Trunnion

205 mm

62.5 mm

metric

65 x 142

DVO Jade Coil

Trunnion

205 mm

60 mm

metric

65 x 142

DVO Jade Coil

Trunnion

205 mm

57.5 mm

metric

65 x 142

DVO Jade Coil

210mm

50mm

metric

55 x 126

DVO Jade Coil

210mm

52.5mm

metric

55 x 126

DVO Jade Coil

210mm

55mm

metric

55 x 126

DVO Jade Coil

Trunnion

185

50

metric

55 x 126

DVO Jade Coil

Trunnion

185

52.5

metric

55 x 126

DVO Jade Coil

Trunnion

185

55

metric

55 x 126

DVO Jade Coil

250 mm

70 mm

metric

75 x 160

DVO Jade Coil

250 mm

75 mm

metric

75 x 162

DVO Jade Coil

Trunnion

225mm

70mm

metric

75 x 162

DVO Jade Coil

Trunnion

225mm

75mm

metric

75 x 162

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

X-Fusion Vector Coil HLR

222 mm /8.75 in

69 mm

Metric/English

65 x 142

X-Fusion Vector Coil HLR

200mm

57mm

metric

55 x 126

X-Fusion Vector Coil HLR

240mm

76mm

metric

75 x 160

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (length x stroke)

Cane Creek DB coil CS

222 mm

63 mm

Metric

65 x 142

Cane Creek DB coil CS

222 mm

66 mm

Metric

65 x 142

Cane Creek DB coil CS

Trunnion

205mm

57.5mm

Metric

65 x 142

Cane Creek DB coil CS

Trunnion

205mm

60mm

Metric

65 x 142

Cane Creek DB coil CS

Trunnion

205mm

65mm

Metric

65 x 142

Cane Creek DB coil CS

230mm

57.5mm

Metric

65 x 142

Cane Creek DB coil CS

230mm

60mm

Metric

65 x 142

Cane Creek DB coil CS

230mm

65mm

Metric

65 x 142

Cane Creek DB coil CS

210mm

50mm

metric

55 x 126

Cane Creek DB coil CS

210mm

52.5mm

metric

55 x 126

Cane Creek DB coil CS

210mm

55mm

metric

55 x 126

Cane Creek DB coil CS

200mm

50mm

metric

55 x 126

Cane Creek DB coil CS

200mm

57mm

metric

55 x 126

Cane Creek DB coil CS

Trunnion

185mm

50mm

metric

55 x 126

Cane Creek DB coil CS

Trunnion

185mm

52.5mm

metric

55 x 126

Cane Creek DB coil CS

Trunnion

185mm

55mm

metric

55 x 126

Cane Creek DB coil CS

250mm

70mm

metric

75 x 162

Cane Creek DB coil CS

250mm

75mm

metric

75 x 162

Cane Creek DB coil CS

Trunnion

225mm

70mm

metric

75 x 162

Cane Creek DB coil CS

Trunnion

225mm

75mm

metric

75 x 162

Cane Creek DB coil IL

210mm

50mm

metric

55 x 126

Cane Creek DB coil IL

210mm

52.5mm

metric

55 x 126

Cane Creek DB coil IL

210mm

55mm

metric

55 x 126

Cane Creek DB coil IL

200mm

50mm

metric

55 x 126

Cane Creek DB coil IL

200mm

57mm

metric

55 x 126

Marzocchi before 2018, some models

65 x 142

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (length x stroke)

Ohlins TTX22 coil

230mm

57.5mm

Metric

65 x 142

Ohlins TTX22 coil

230mm

60mm

Metric

65 x 142

Ohlins TTX22 coil

230mm

65mm

Metric

65 x 142

Ohlins TTX22 coil

Trunnion

205mm

65mm

Metric

65 x 142

Ohlins TTX22 coil

210mm

50mm

metric

55 x 126

Ohlins TTX22 coil

Trunnion

185mm

55mm

metric

55 x 126

Ohlins TTX22 coil

7.87 inch

2.0 inch

English

55 x 126

Ohlins TTX22 coil

7.87 inch

2.25 inch

English

55 x 126

Ohlins TTX22 coil

9.5 inch

3.0 inch

English

75 x 162

Ohlins TTX22 coil

Trunnion

225mm

70mm

metric

75 x 162

Ohlins TTX22 coil

Trunnion

225mm

75mm

metric

75 x 162

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

Rockshox Super Deluxe Coil RCT

230mm

60mm

metric

65 x 142

Rockshox Super Deluxe Coil RCT

230mm

65mm

metric

65 x 142

Rockshox Super Deluxe Coil RC World Cup

230mm

60mm

metric

65 x 142

Rockshox Super Deluxe Coil RT Remote

230mm

60mm

metric

65 x 142

Rockshox Super Deluxe Coil RT Remote

230mm

65mm

metric

65 x 142

Rockshox Super Deluxe Coil R

230mm

60mm

metric

65 x 142

Rockshox Super Deluxe Coil R

230mm

65mm

metric

65 x 142

Rockshox Super Deluxe Coil RCT

Trunnion

205mm

57.5mm

metric

65 x 142

Rockshox Super Deluxe Coil RCT

Trunnion

205mm

60mm

metric

65 x 142

Rockshox Super Deluxe Coil RCT

Trunnion

205mm

65mm

metric

65 x 142

Rockshox Super Deluxe Coil RCT

210mm

55mm

metric

55 x 126

Rockshox Super Deluxe Coil RT Remote

200mm

57mm

metric

55 x 126

Rockshox Super Deluxe Coil RC World Cup

250mm

75mm

metric

75 x 162

Rockshox Super Deluxe RC

Trunnion

225mm

70mm

metric

75 x 162

Rockshox Super Deluxe RC

Trunnion

225mm

75mm

metric

75 x 162

Shock Brand/Model

Regular or Trunnion

Shock eye to eye

Stroke

Metric / English

Sprindex spring family (stroke x length)

Rockshox Vivid

200

57

55 x 126

Rockshox Vivid

216

63

65 x 142

Rockshox Vivid

222

70

65 x 142

Rockshox Vivid

240

76

75 x 162

Push

2.25 inch

English

55 x 126

Push

2.5 inch

English

65 x 142

Extreme Racing

EXT STORIA LOK V3

200

57

English

55 x 126

EXT STORIA LOK V3

217

63.5

English

65 x 142

EXT STORIA LOK V3

222

67

English

65 x 142

EXT STORIA LOK V3

210

50

Metric

55 x 126

EXT STORIA LOK V3

210

52.5

Metric

55 x 126

EXT STORIA LOK V3

210

55

Metric

55 x 126

EXT STORIA LOK V3

230

57.5

Metric

65 x 142

EXT STORIA LOK V3

230

60

Metric

65 x 142

EXT STORIA LOK V3

230

62.5

Metric

65 x 142

EXT STORIA LOK V3

230

65

Metric

65 x 142

EXT STORIA LOK V3

250

67.5

Metric

75 x 162

EXT STORIA LOK V3

250

70

Metric

75 x 162

EXT STORIA LOK V3

250

72.5

Metric

75 x 162

EXT STORIA LOK V3

250

75

Metric

75 x 162

EXT STORIA LOK V3

Trunnion

185

50

Metric

55 x 126

EXT STORIA LOK V3

Trunnion

185

52.5

Metric

55 x 126

EXT STORIA LOK V3

Trunnion

185

55

Metric

55 x 126

EXT STORIA LOK V3

Trunnion

205

57.5

Metric

65 x 142

EXT STORIA LOK V3

Trunnion

205

60

Metric

65 x 142

EXT STORIA LOK V3

Trunnion

205

62.5

Metric

65 x 142

EXT STORIA LOK V3

Trunnion

205

65

Metric

65 x 142

EXT STORIA LOK V3

Trunnion

225

67.5

Metric

75 x 162

EXT STORIA LOK V3

Trunnion

225

70

Metric

75 x 162

EXT STORIA LOK V3

Trunnion

225

72.5

Metric

75 x 162

EXT STORIA LOK V3

Trunnion

225

75

Metric

75 x 162

EXT STORIA LOK

200

57

English

55 x 126

EXT STORIA LOK

217

63.5

English

65 x 142

EXT STORIA LOK

210

50

Metric

55 x 126

EXT STORIA LOK

210

55

Metric

55 x 126

EXT STORIA LOK

230

60

Metric

65 x 142

EXT STORIA LOK

230

65

Metric

65 x 142

DH Racing:

EXT ARMA HBC V3

222

67

Metric

65 x 142

EXT ARMA HBC V3

241

74

Metric

75 x 162

EXT ARMA HBC V3

230

57.5

Metric

65 x 142

EXT ARMA HBC V3

230

60

Metric

65 x 142

EXT ARMA HBC V3

230

62.5

Metric

65 x 142

EXT ARMA HBC V3

230

65

Metric

65 x 142

EXT ARMA HBC V3

250

70

Metric

75 x 162

EXT ARMA HBC V3

250

72.5

Metric

75 x 162

EXT ARMA HBC V3

250

75

Metric

75 x 162

EXT ARMA HBC V3

Trunnion

205

57.5

Metric

65 x 142

EXT ARMA HBC V3

Trunnion

205

60

Metric

65 x 142

EXT ARMA HBC V3

Trunnion

205

62.5

Metric

65 x 142

EXT ARMA HBC V3

Trunnion

205

65

Metric

65 x 142

EXT ARMA HBC V3

Trunnion

225

70

Metric

75 x 162

EXT ARMA HBC V3

Trunnion

225

72.5

Metric

75 x 162

EXT ARMA HBC V3

Trunnion

225

75

Metric

75 x 162

EXT ARMA HBC

222

70

Metric

75 x 162

EXT ARMA HBC

241

76

Metric

75 x 162


PERFORMANCE ADAPTERS

Performance Adapters are included. Sprindex coils fit a wide variety of shocks, but you must use the Performance Adapter for most of them. Our Performance Adapters both improve the fit between the coil and your shock and are made of low friction Delrin to improve shock performance by allowing the spring to twist during high deflection. See bottom of Performance Adapter for direction of which adapter you should use. For Rockshox, no adapter is necessary but we recommend you use the Performance Washer Adapter for shock performance.

COIL DIRECTION

The Sprindex coil can be installed in either direction and should be installed in the direction that provides the best adjusting access. If your entire shock has good access, then install the Sprindex with the Dial away from the piggyback for easiest hand access.

ADJUSTING SPRING RATE

To adjust the spring rate, hold the coil with one hand and twist the Dial with your other hand or vice versa. The spring rate value is identified by the printed number on the coil displayed through the Dial opening. Preload is not a substitute for a spring that is too weak.

Metric Spring Rate Conversion

Spring rate is shown in pounds per inch (lb/in) on Sprindex coils. Below is a conversion from lb/in to N/mm.

Lb/in

350

360

370

380

390

400

410

420

430

440

450

N/mm

61

63

65

67

68

70

72

74

75

77

79

Lb/in

460

470

480

490

500

510

520

530

540

550

560

N/mm

81

82

84

86

88

89

91

93

95

96

98