What size GT bike should I get for 5'10" (178 cm)?

At 5'10" (178 cm) most riders fit a Large GT mountain bike (height range 176-188 cm), a Medium or Large gravel frame on the Grade (Medium 170-180 cm overlaps with Large 178-189 cm), and a Medium hybrid (170-181 cm). For aggressive trail riding on the Sensor or Force, many riders pick the Medium (168-178 cm) for snappier handling; if you ride longer mileage or value descending stability, stay with the Large. Inseam in the 82-87 cm range usually confirms the Large is the better all-rounder.

What size GT Sensor for 5'8" (173 cm)?

A 5'8" (173 cm) rider with a 78-80 cm inseam fits the Medium GT Sensor (height range 168-178 cm, stack 620 mm, reach 458 mm). The Triple Triangle rear end adds compliance that lets the published range fit honestly, so most trail riders at this height stay on the Medium. If you mostly ride bike-park and steep descents, the Small (160-170 cm) gives a more flickable feel; if you prioritize pedaling efficiency on long XC rides, the Medium is the right call.

Is GT sizing the same as Trek or Specialized mountain bikes?

GT runs slightly more conservative in reach than Trek and Specialized at the same letter size. A GT Medium Sensor has a 458 mm reach versus 460 mm on a Medium Trek Fuel EX and 465 mm on a Medium Specialized Stumpjumper. Stack is within 5-8 mm across all three. If you're moving from a Trek or Specialized Medium and want the same cockpit length, the GT Medium will feel marginally shorter; sizing up to a Large only makes sense if you also want more standover and a more stretched-out descending position.

Do GT bikes run true to size?

Yes. GT's published height ranges land close to real-world fit, helped by the Triple Triangle seatstay design that adds vertical compliance and forgives small fit deviations. The two cases where riders deviate are the Force enduro (size down a frame if you prioritize a playful, in-the-air feel) and the Zaskar XC hardtail (stay on-size and shorten the stem if you want a racier cockpit). The Aggressor entry-level hardtail and the Grade gravel bike both fit straight to the chart for new riders.

Does GT use its BMX heritage in the way it sizes adult bikes?

Yes, indirectly. GT's mountain and gravel geometries encourage a centered, active riding position rooted in their BMX and dirt-jump background, which is why their reach numbers (458 mm Medium Sensor, 472 mm Medium Force) sit on the longer side of the trail bike norm. Practically that means GT riders often prefer a shorter stem (40-50 mm on trail, 50-60 mm on gravel) at their recommended size rather than dropping a frame size. The Triple Triangle rear end then maintains compliance even with longer front-center geometry.

GT Bike Size Chart

Size chart and fit guide for 2026

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GT's iconic Triple Triangle frame design isn't just visual-it provides additional rear-end stiffness and compliance that influences how each size rides, giving their bikes a distinct feel under power. With roots in BMX and decades of gravity racing heritage, GT sizes their bikes to encourage an active, centered riding position that rewards riders who like to push their limits on varied terrain.

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GT Size Charts by Category

GT Mountain Bike Size Chart

Size	Height Range	Inseam Range
XS	4'12" - 5'4"(152 - 162 cm)	26.4" - 28.7"(67 - 73 cm)
S	5'3" - 5'7"(160 - 170 cm)	28.3" - 30.7"(72 - 78 cm)
M	5'6" - 5'10"(168 - 178 cm)	30.3" - 32.7"(77 - 83 cm)
L	5'9" - 6'2"(176 - 188 cm)	32.3" - 35.0"(82 - 89 cm)
XL	6'1" - 6'6"(186 - 198 cm)	34.6" - 37.4"(88 - 95 cm)

Height: 4'12" – 5'4" (152–162 cm)

Inseam: 26.4" – 28.7" (67–73 cm)

Height: 5'3" – 5'7" (160–170 cm)

Inseam: 28.3" – 30.7" (72–78 cm)

Height: 5'6" – 5'10" (168–178 cm)

Inseam: 30.3" – 32.7" (77–83 cm)

Height: 5'9" – 6'2" (176–188 cm)

Inseam: 32.3" – 35.0" (82–89 cm)

Height: 6'1" – 6'6" (186–198 cm)

Inseam: 34.6" – 37.4" (88–95 cm)

GT Gravel Bike Size Chart

Size	Height Range	Inseam Range
XS	5'1" - 5'5"(155 - 164 cm)	27.2" - 29.5"(69 - 75 cm)
S	5'4" - 5'8"(162 - 172 cm)	29.1" - 31.1"(74 - 79 cm)
M	5'7" - 5'11"(170 - 180 cm)	30.7" - 33.1"(78 - 84 cm)
L	5'10" - 6'2"(178 - 189 cm)	32.7" - 35.0"(83 - 89 cm)
XL	6'2" - 6'6"(187 - 198 cm)	34.6" - 37.4"(88 - 95 cm)

Height: 5'1" – 5'5" (155–164 cm)

Inseam: 27.2" – 29.5" (69–75 cm)

Height: 5'4" – 5'8" (162–172 cm)

Inseam: 29.1" – 31.1" (74–79 cm)

Height: 5'7" – 5'11" (170–180 cm)

Inseam: 30.7" – 33.1" (78–84 cm)

Height: 5'10" – 6'2" (178–189 cm)

Inseam: 32.7" – 35.0" (83–89 cm)

Height: 6'2" – 6'6" (187–198 cm)

Inseam: 34.6" – 37.4" (88–95 cm)

GT Hybrid Bike Size Chart

Size	Height Range	Inseam Range
XS	5'0" - 5'4"(153 - 163 cm)	26.8" - 29.1"(68 - 74 cm)
S	5'3" - 5'8"(161 - 172 cm)	28.7" - 31.1"(73 - 79 cm)
M	5'7" - 5'11"(170 - 181 cm)	30.7" - 33.1"(78 - 84 cm)
L	5'10" - 6'3"(179 - 190 cm)	32.7" - 35.4"(83 - 90 cm)
XL	6'2" - 6'7"(188 - 200 cm)	35.0" - 37.8"(89 - 96 cm)

Height: 5'0" – 5'4" (153–163 cm)

Inseam: 26.8" – 29.1" (68–74 cm)

Height: 5'3" – 5'8" (161–172 cm)

Inseam: 28.7" – 31.1" (73–79 cm)

Height: 5'7" – 5'11" (170–181 cm)

Inseam: 30.7" – 33.1" (78–84 cm)

Height: 5'10" – 6'3" (179–190 cm)

Inseam: 32.7" – 35.4" (83–90 cm)

How to Measure

• Height: Stand barefoot against a wall and measure from floor to top of head
• Inseam: Stand with feet 6 inches apart, measure from floor to crotch
• Arm Reach: For road bikes, measure from shoulder to fingertips

When Between Sizes

• Comfort priority: Choose the larger size
• Performance priority: Choose the smaller size
• Long torso: Size up for better reach
• Long legs: Size down for better standover

GT Sizing FAQ

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Where to go from your GT sizing

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Calculate your frame sizePunch in your height and inseam to get a size estimate in under a minute.Compare two bikesPut geometry and fit side by side before you commit to one.Find gear for your GTBrowse helmets, saddles, lights, and locks sized for your setup.

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