Chain & Sprockets
- 2014–Present Honda Grom 125 — stock front sprocket (15T)
Additional fitment at the bottom.
Product Overview
This is a JT Sprockets 15-tooth 420-pitch front sprocket for the Honda Grom 125. The Grom runs a 15-tooth front sprocket stock with 420-pitch chain across all generations from 2014 to present. This is a direct stock replacement — no gearing change, no chain change required.
Key Technology & Design
JT makes this sprocket from SCM420/20CrMo chromoly steel alloy, heat-treated and bead-blasted to reduce surface tension. Natural finish.
Specs
- Tooth Count: 15
- Chain Pitch: 420
- Position: Countershaft (front)
- Material: SCM420/20CrMo chromoly steel alloy
- Finish: Natural
- Manufacturer Part Number: JTF249.15
Fitment
Year(s) — Make / Model — Stock Gearing — Stock Chain
| 2022–Present | Honda Grom 125 | 15T / 38T | 420 |
| 2014–2020 | Honda Grom 125 | 15T / 34T | 420 |
Additional Fitment
Year(s) — Make / Model — Stock Gearing — Stock Chain
| 2019–2021 | Honda Monkey | ||
| 1988–1990 | Kawasaki KD80 |
Gearing — Staying Stock or Making a Change
This sprocket matches the stock 15-tooth front on the Grom across all generations. Installing it keeps your bike at factory stock gearing.
If you are considering a gearing change, here is the general framework. Going one tooth smaller on the front shortens gearing — quicker acceleration, higher RPM at speed, reduced top speed. Going one tooth larger lengthens gearing — lower RPM at cruise, softer pull from a stop. On a small-displacement bike like the Grom the effect of a one-tooth front change is noticeable.
Stock gearing is well matched for general street and urban use. Neither direction is right or wrong — it depends on how and where you ride.
" ["features"]=> string(0) "" ["specifications"]=> string(0) "" ["warehouseFulfillment"]=> bool(false) ["loyaltyRewardAmount"]=> float(0.33) ["productID"]=> int(356) ["category"]=> string(2) "17" ["categoryName"]=> string(17) "Chain & Sprockets" ["categoryObj"]=> array(10) { ["categoryID"]=> int(17) ["parentID"]=> int(9991) ["name"]=> string(17) "Chain & Sprockets" ["slug"]=> string(15) "chain-sprockets" ["children"]=> array(0) { } ["metaTitle"]=> string(0) "" ["metaDescription"]=> string(0) "" ["metaKeywords"]=> string(0) "" ["fitmentOverride"]=> bool(true) ["fitmentOverrideDescription"]=> string(180) "IMPORTANT: Please Review Your Owner’s Manual for Exact Amounts or Sizing of This Product!
" } ["brand"]=> string(12) "JT Sprockets" ["name"]=> string(46) "15T Front Sprocket - 420 (Honda Grom + Monkey)" ["sku"]=> string(9) "1212-0225" ["slug"]=> string(43) "jt-sprockets-15-tooth-countershaft-sprocket" ["price"]=> float(6.53) ["salePrice"]=> NULL ["isClearance"]=> bool(false) ["weight"]=> float(16) ["excludeFromLoyalty"]=> bool(false) ["images"]=> array(1) { [0]=> array(3) { ["filename"]=> string(117) "https://s3.us-east-2.amazonaws.com/usedbikesdirect.prod.public/product-parts/4cf01845-6983-48ed-b79b-0bc1a5d6e54a.png" ["name"]=> string(40) "F58EA4E4-0EF9-4D8F-8336-A92A1B0B3FD3.png" ["sortOrder"]=> int(1) } } ["tag"]=> string(8) "IN STOCK" ["colorVariant"]=> NULL } ["hasData"]=> bool(true) ["count"]=> int(1) ["isError"]=> bool(false) ["isWarning"]=> bool(false) ["errors"]=> array(0) { } ["warnings"]=> array(0) { } ["hasErrors"]=> bool(false) ["hasWarnings"]=> bool(false) ["message"]=> string(7) "Success" }15T Front Sprocket – 420 (Honda Grom + Monkey)
IMPORTANT: Please Review Your Owner’s Manual for Exact Amounts or Sizing of This Product!
Speak to one of our experts today:
469-490-3577
JT Sprockets
SKU:1212-0225
Description:JT Sprockets 15-Tooth 420 Front Sprocket — Honda Grom 125
Main Fitment:
- 2014–Present Honda Grom 125 — stock front sprocket (15T)
Additional fitment at the bottom.
Product Overview
This is a JT Sprockets 15-tooth 420-pitch front sprocket for the Honda Grom 125. The Grom runs a 15-tooth front sprocket stock with 420-pitch chain across all generations from 2014 to present. This is a direct stock replacement — no gearing change, no chain change required.
Key Technology & Design
JT makes this sprocket from SCM420/20CrMo chromoly steel alloy, heat-treated and bead-blasted to reduce surface tension. Natural finish.
Specs
- Tooth Count: 15
- Chain Pitch: 420
- Position: Countershaft (front)
- Material: SCM420/20CrMo chromoly steel alloy
- Finish: Natural
- Manufacturer Part Number: JTF249.15
Fitment
Year(s) — Make / Model — Stock Gearing — Stock Chain
| 2022–Present | Honda Grom 125 | 15T / 38T | 420 |
| 2014–2020 | Honda Grom 125 | 15T / 34T | 420 |
Additional Fitment
Year(s) — Make / Model — Stock Gearing — Stock Chain
| 2019–2021 | Honda Monkey | ||
| 1988–1990 | Kawasaki KD80 |
Gearing — Staying Stock or Making a Change
This sprocket matches the stock 15-tooth front on the Grom across all generations. Installing it keeps your bike at factory stock gearing.
If you are considering a gearing change, here is the general framework. Going one tooth smaller on the front shortens gearing — quicker acceleration, higher RPM at speed, reduced top speed. Going one tooth larger lengthens gearing — lower RPM at cruise, softer pull from a stop. On a small-displacement bike like the Grom the effect of a one-tooth front change is noticeable.
Stock gearing is well matched for general street and urban use. Neither direction is right or wrong — it depends on how and where you ride.
