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Build Overview
This one started life as a stock Jamis Portal C3 with a full Shimano SLX drivetrain, but I wanted to spend some time on it set up more like the bikes I usually ride. I ended up turning it into a SRAM build and using it as a personal demo bike this fall to see how the Platform felt on our local trails.
The frame, fork, and shock are all stock Portal C3, but the bike now leaves the shop with a SRAM GX Eagle drivetrain, Truvativ Descendant crank, SRAM G2 R brakes, and a DT Swiss M 1900 wheelset in place of the stock wheels. The cockpit, dropper, and tires are still original to the bike.
It pedals really well for a 130 mm trail bike, handles rocks and drops confidently, and it was honestly one of the more surprising bikes I’ve ridden. I liked it enough that after riding this one, we decided to bring more Portals into the shop.
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Full Build Specs
- Frame: Jamis Portal C3 carbon trail frame
- Travel / Setup: 130 mm travel trail bike, rear suspension set in the high position
- Fork: Fox 34 Performance, 130 mm travel (stock)
- Rear Shock: Fox Performance series rear shock (stock)
- Wheelset: DT Swiss M 1900 wheels (from a Niner 3-star GX build)
- Front Tire: Original stock Jamis Portal tire (new)
- Rear Tire: Original stock Jamis Portal tire (new)
- Drivetrain: SRAM GX Eagle 12-speed drivetrain
- Cassette: SRAM GX Eagle cassette
- Rear Derailleur: SRAM GX Eagle rear derailleur
- Crankset: Truvativ Descendant crank
- Brakes: SRAM G2 R hydraulic disc brakes
- Handlebar: Original stock handlebar
- Dropper Post: Race Face Aeffect dropper post
- Pedals: Not included / as shown in photos (shop demo setup may differ)
Build Notes
This Portal came in from the factory as a C3 build with a full Shimano SLX drivetrain. We ride a lot of off-road and I’m very used to SRAM, especially their brakes, so when I decided to use this as a demo bike I pulled the Shimano kit and set it up in a SRAM configuration.
For part of the demo period I actually had it built even higher-end than you see here: I ran a SRAM GX AXS Eagle rear derailleur and an XX Transmission crank with a power meter on it. The frame doesn’t use a UDH yet, so I had to get a little creative with chainline and spacing, but it worked surprisingly well. That crank and power meter were mine, though, so those came back off before the bike went out the door.
The bike now leaves as a very solid, practical build: Fox 34 Performance fork, Fox Performance rear shock, SRAM GX Eagle drivetrain, Descendant crank, G2 R brakes, and DT Swiss M 1900 wheels, with the original cockpit, dropper, and fresh stock tires. It started as a Shimano build, but it’s 100% a SRAM bike now.
On trail, this Portal was one of the better pedaling trail bikes I’ve ridden. It feels efficient on the climbs, still happy to be pushed through rocks and off small drops, and just a fun bike to spend time on. I rode it in the high position and even with worn tires on my own wheelset it felt fast and lively. After riding it, we ended up bringing more Portals into the shop because it impressed me that much.
This particular bike ended up being a nice way to get a customer onto better suspension, a nicer wheelset, and a much nicer drivetrain than a stock C4, while still staying within that C4 price range. We do this kind of thing a lot—using our demo builds and parts we trust to put together bikes that punch above their stock spec for the money.
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