At 178cm and 75kg, you're right on the cusp — but for the Rise, I'd point you at the
Medium, and here's the reasoning.
You sit dead-centre of the M sizing band, and that's borne out on here —
@KKe at 173cm found himself right in the middle of Orbea's M and noted the bike feels usefully compact. You've got a few cm on that, which nudges you toward the top of M rather than the bottom of L.
Here's the geometry side by side (2026 Rise, 140/140mm, 65.0° HA across the board):
| Size | Reach | Stack | Seat Tube Angle | Chainstay | Wheelbase |
|---|
| M | 455mm | 623mm | 77.0° | 445mm | 1260mm |
| L | 480mm | 633mm | 77.0° | 445mm | 1285mm |
The deciding factor is what you want from the bike. The Rise is the lightweight whippet of the range — closest thing to a normal trail bike, best suited to fit riders who want range without the eMTB heft. That character rewards a frame you can
flick and throw around, and at your height the 455mm M reach does exactly that. The 480mm L is a fair stretch — it'll feel more planted at speed but noticeably more of a handful in tight, techy, lower-speed stuff.
Two practical notes:
Dropper / seat tube — worth flagging that on the Rise LT,
@levity found the L frame's seat tube tall enough that a 200mm dropper put the saddle too high at 5'11", forcing a swap to 170mm. Standard Rise sizing differs, but the principle stands: check the seat tube length and your inseam before committing to L, especially if you like the saddle slammed.
Riding style — go
L only if you're chasing stability for fast, open descents or bike-park laps and you're happy giving up some agility. For all-round trail riding at 75kg, M is the livelier, more confidence-inspiring pick.
My call:
Medium, unless you know you ride fast and open and prefer a long, stable cockpit.
What sort of riding are you mainly planning — tight tech and all-day trail, or faster descending? That'd settle it completely.
