BMC Blast 20

2021 YouthMountain youth Manufacturer page

Suspension: Rigid
Wheels: 20″
Drivetrain: 1 × 8 32t / 11–34t
Gear range: 309%
Weight: 9.18 kg 20.2 lb · Reference configuration not specified
Frame: Aluminum
Brakes: Hydraulic disc

Rider height by size (cm)

Size guide

20" 110–135

Components

10 of 17 identified

Parts found in a manufacturer catalog show their brand, model and key numbers, and the steps show how precisely they are identified: brand, series, model, or the exact product. The info button has every detail and the text the manufacturer published.

Frame and fork

1 part

Frame

Blast 20" Lightweight Aluminium with Powder Coat Finish, • 1 1/8"" Head Tube, • BSA Threaded Bottom Bracket, • 140mm Post Mount, • 9X135mm QR Not identified

Suspension

1 part

Fork

Blast 20" Lightweight Aluminium with Powder Coat Finish, • 140mm Post Mount, • 9X100mm QR Not identified

Drivetrain

6 parts

Bottom bracket

BSA, threaded Not identified
Cassette
- SunRace 11–34t
Chain
- SRAM
Crankset

Lightweight Forged Alloy Cranks, 32T 1x Specific Narrow Wide chainring, 127mm Not identified
Rear derailleur
- SRAM X4 7 speeds
Shifters
- SRAM X4 Trigger 3 speeds

Brakes

1 part

Brakes
- Tektro
HD-M286

Wheels and tires

4 parts

Front hub

CNC Machined Alloy Hub Body, Sealed Bearings, Quick Release Not identified
Rear hub

CNC Machined Alloy Hub Body, Sealed Bearings, Quick Release Not identified
Rims
- Alex Rims
Tires
- Kenda Booster

Cockpit and contact points

4 parts

Handlebar
- SDG Slater
Saddle
- SDG FLY
Seatpost

Alloy 27.2mm, 300mm long Not identified
Stem
- BMC

Sizes and geometry

1 size Open in the geometry plotter

Enter your height to highlight matching ranges.

Size 20"

Table

Reach 305mm

Stack 412mm

Wheelbase 833mm

Head angle 68.0°

Seat angle 73.0°

Every size is drawn to the same scale, in millimeters. Explanatory schematic on an assumed 20″ wheel; exact published values are in the table below.

Size Reported by the manufacturer

Complete manufacturer geometry table 1 published size

Complete manufacturer geometry by size
Measurement
Frame
Reachmm	305
Stackmm	412
Top tube lengthmm	431
Seat tube lengthmm	275
Head tube lengthmm	105
Head tube angle	68°
Seat tube angle	73°
Chainstay lengthmm	342
Wheelbasemm	833
Front centermm	455
Bottom bracket dropmm	40
Standover heightmm	490
Fork rakemm	35
Trailmm	66
Stack/reach ratio	1.35
Suspension and parts
Crank lengthmm	127
Handlebar widthmm	650
Stem lengthmm	40
Stem angle	6°
Seatpost lengthmm	300

Not published by the manufacturer: Bottom bracket height, Front travel, Rear travel and Dropper post travel.

Specifications

Frame and fork

Intended fit: Unisex
Frame material: Aluminum
Fork material: Aluminum
Bicycle weight: 9.18 kg

20.2 lb

Suspension

Suspension configuration: Rigid

Drivetrain

Derived by Bikelake

Front chainrings: 1
Smallest chainring: 32
Largest chainring: 32
Rear sprockets: 8
Smallest sprocket: 11
Largest sprocket: 34
Lowest gear: 18.8 in
Highest gear: 58.2 in

Wheels and brakes

Wheel configuration: Same size
Brake type: Hydraulic disc

Fit and controls

Seatpost: Rigid seatpost
Shifting: Mechanical

Additional specifications

Bottom bracket standard: BSA
Tire width: 2.4″
Travel: Front: Additional specification: Not available: Yes
Rear: Additional specification: Not available: Yes
Wheel material: Aluminum
Wheel size: 20″

Technical analysis

2 measures

How these figures sit among bicycles of the same class and model year. Context, not a ranking.

Lowest gear

18.8 gear inches

This value is within the central range for this class.

Cohort: Youth / Mountain youth Model year: 2021
Sample: 230 bicycles with this information
Coverage: 72.3% of the class

Highest gear

58.2 gear inches

This value is within the central range for this class.

Cohort: Youth / Mountain youth Model year: 2021
Sample: 230 bicycles with this information
Coverage: 72.3% of the class

Gearing

Estimated speeds at 80 rpm

Lowest gear: 7.2 km/h
Highest gear: 22.3 km/h

Total gear range 309%

Technical details and class reference

These speeds describe the gearing at the selected cadence, not how fast you can ride.
Calculated from published gear-inch values and their wheel-size assumptions.
These gearing values describe the bicycle, not a selected frame size.
A 100% range means one ratio; 500% means the highest ratio is five times the lowest.
For e-bikes, motor assistance cutoff is not represented.

Gear-inch range

Lower gear-inch values travel less distance per pedal revolution; higher values travel farther.

This bicycle: 18.8–58.2 gear inches
Class reference (p10–p90): 15.6–80.0 gear inches; The band runs from p10 for the lowest gear to p90 for the highest gear.

Cohort: Youth / Mountain youth Model year: 2021
Lowest gear: 230 bicycles with this information, 72.3% of the class
Highest gear: 230 bicycles with this information, 72.3% of the class

Lineup changes

The published facts that differ across this family's builds and from the same model a year earlier. Missing information never counts as zero.

Differences across 2021 builds

Differences across 2021 builds
Specification	This bicycle BMC Blast 20	BMC Blast 27
Frame
Frame material	Aluminum	Not informed
Fork material	Aluminum	Not informed
Bicycle weight	9.18 kg	13.46 kg
Weight limit	Not informed	110 kg
Suspension
Suspension configuration	Rigid	Hardtail
Front travel	Not informed	100 mm
Drivetrain
Rear sprockets	8	10
Smallest sprocket	11	10
Largest sprocket	34	46
Lowest gear	18.8 in	19.1 in
Highest gear	58.2 in	88.0 in
Other specifications
Suspension	Rigid	Hardtail
Tire width	2.4″	2.2″
Wheel size	20″	27.5″
Fork spring	Not informed	Coil