absoluteBLACK's Spiderless Boost is a CNC machined, shift-able oval Boost chainring, especially build for GXP and BB30 cranks. It converts any SRAM crank into Boost 148 specific setup needed in Boost equipped bikes. Boost and non-Boost SRAM cranks are identical. All the offset is achieved by the chainring itself, so you can use any SRAM crank for this conversion. absoluteBLACK's regular GXP Oval chainrings have 6 mm offset whether this one has 3 mm.
The fine design of the absoluteBLACK Spiderless Boost Oval chainring provides an excellent weight to strength ratio. It saves weight because it doesn't need the spider and chainring bolts. And the special 3D teeth machining for ultimate mud relief decreases wear and noise dramatically. For this the Oval Boost chainrings use the advantages of their elliptical, patent pending form perfectly. So you receive the ability to install smaller ring sizes that can't be mounted on regular spiders. While climbing they are easier on legs and reduce the stress on your knees.
The chainring is dedicated for Boost 148 bikes only.
Functioning of oval chainrings
Oval chainrings work because a rider does not produce power evenly through a pedal stroke. They maximize the part of the stroke where power is produced and minimize resistance where it isn't. Oval rings make the spin cycle a lot smoother and are easier on legs while climbing. A round chainring doesn't transfer torque to your rear wheel as smoothly as an Oval one. You will actually feel your stroke to be more "round" with an oval shape than with a round chainring.
- SRAM XX1, X01, X0, X9, X7, S2210, S1400, Truvativ AKA
- GXP and BB30 with long spindles
- only for Boost 148 bikes
52 mm, especially for Boost 148
110.5° to 116.3° after TDC (top dead center)
optimized to each size separately (at range from 10.2% to 14.4%):
SRAM, GXP, Eagle and XX1 are trademarks of SRAM LLC and are used for informational purposes only.
- 28T: ovality of 26/30T / best for someone who uses currently 27 or 28T round ring
- 30T: ovality of 28/32T / best for someone who uses currently 29 or 30T round ring
- 32T: while pedaling similar effort to riding a round 31T ring, but speed similar to riding a 34T chainring / best for someone who uses currently 31 or 32T
- 34T: ovality of 32/36T / best for someone who uses currently 33 or 34T round ring