Yes, replacement lower legs are available for the 2020 SID B4. Lower legs are wheel-size and travel-specific.
27.5”:
11.4018.006.267 FORK LOWER LEG - (DECALS NOT INCLUDED) 27 15X110 BOOST™ DIFFUSION BLACK - SID RLC A1/SID XX/RL B1 (2017+) REBA A7 (2018+) SID SELECT/SELECT+ B4 80-100MM (2020+)
11.4018.006.265 FORK LOWER LEG - (DECALS NOT INCLUDED) 27 15X110 BOOST™ BLACK - SID RLC A1/SID XX/RL B1 (2017+) REBA 80-100MM A7 (2018+) SID SELECT/SELECT+ B4 80-100MM (2020+)
29”:
11.4018.006.264 FORK LOWER LEG - (DECALS NOT INCLUDED) 29 15X110 BOOST™ DIFFUSION BLACK - SID RLC A1/SID XX/RL B1 (2017+) REBA A7 (2018+) SID SELECT/SELECT+ B4 80-100MM (2020+)
11.4018.006.262 FORK LOWER LEG - (DECALS NOT INCLUDED) 29 15X110 BOOST™ BLACK - SID RLC A1/SID XX/RL B1 (2017+) REBA 80-100MM A7 (2018+) SID SELECT/SELECT+ B4 80-100MM (2020+)
11.4018.006.231 FORK LOWER LEG - (DECALS NOT INCLUDED) 29 15X110 BOOST™ BLACK - SID A1-A4 (2011-2016),REBA (A1-A5/2012-2017), REBA A7 120MM (2018+) SID SELECT/SELECT+ 110-120MM B4 (2020+)
11.4018.006.233 FORK LOWER LEG - (DECALS NOT INCLUDED) 29 15X110 BOOST™ DIFFUSION BLACK - SID A1-A4 (2011-2016),REBA (A1-A5/2012-2017), REBA A7 (2018+) SID SELECT/SELECT+ 110-120MM B4 (2020+)
RockShox service kits and spare parts are best obtained through your local shop or dealer. See our dealer locator, below, to find a dealer near you. If no one is currently listed near you, then please search for local shops via your preferred web browser.
https://www.sram.com/en/dealer-locator
Manuals and additional information about RockShox and SRAM components can be found at our service site, linked below.
https://www.sram.com/en/service
Further questions?
Reach out to Rider Support by Asking A Question at the link below.
https://www.sram.com/en/rockshox/campaigns/rockshox-rider-support