I asked four people who commute by bicycle eastbound over the I-90 bridge to Microsoft main campus what route they take, and they gave three different answers. I’ve given them meaningless names just to tell them apart.

The yellow route

First half (markers A1 through A5) | Second half (markers B1 through B5).
Animated version: Click markers 1 through 5 in order then markers 1 through 5 in order.
Pro: Avoids downtown Bellevue Con: You’re stuck on Bel-Red

• Get to the I-90 bridge eastbound.
• After crossing the bridge, stay on the trail when it twists under I-90; do not get off into the neighborhood. You will be on a trail parallel to SE Lake Rd (marker A1).
• You will reach a fork in the trail. Bear right and take the bridge.
• Ride through the park until the trail ends, putting you on 118th Ave SE (marker A2).
• Turn left (north). Bellevue Transportation Department recommends riding on west (left) side to reach bike path.
• Turn right onto SE 8th St (marker A3) and go under I-405.
• Cross Lake Hills Connector; the road name changes to SE 7th Pl.
• Turn left onto 128th Ave SE (marker A4).
• The road turns to trail after NE 7th St; turn right onto NE 8th St (marker A5 = marker B1).
  • Alternate route: Turn right onto Main St. and zig-zag through the neighborhood for a less hilly approach.
• Turn left onto 132nd Ave NE or 134th Ave NE, depending on traffic (marker B2).
• Turn right onto Bel-Red Road (marker B3).
• Take Bel-Red Road to Microsoft main campus (markers B4 and B5).

The blue route (two votes)

First half (markers C1 through C5) | Second half (markers D1 through D5).
Animated version: Click markers 1 through 5 in order then markers 1 through 5 in order.
Pro: Avoids downtown Bellevue and Bel-Red Con: Extremely hazardous intersection at the end

• Get to the I-90 bridge eastbound.
• After crossing the bridge, stay on the trail when it twists under I-90; do not get off into the neighborhood. You will be on a trail parallel to SE Lake Rd (marker C1).
• You will reach a fork in the trail. Bear right and take the bridge.
• Ride through the park until the trail ends, putting you on 118th Ave SE (marker C2). Turn right (south).
• Hazardous crossing – busy street, look both ways: Immediately after the underpass, turn left to get back on the I-90 trail (marker C3). Note: hill climb.
• Cross Richards Road, ascend hill, turn left at 142nd Pl SE (marker C4).
• Take the 142nd Pl bridge into Bellevue Community College and meander through the campus to 145th Pl SE (marker C5 = marker D1).
• Turn right onto Lake Hills Blvd (marker D2).
• Take Lake Hill Blvd across 148th, 156th, turning left onto 164th Ave SE (marker D3).
• Follow 164th Ave SE until it ends at NE 30th St (marker D4).
• Turn left and stop at Bel-Red Road (marker D5).
• Extremely hazardous intersection. Cross Bel-Red, taking the back entrance to Microsoft main campus.

You can avoid the hazardous intersection by taking a left onto NE 24th St. and turning right onto 156th Ave NE.

The brown route

First half (markers E1 through E5) | Second half (markers F1 through F5).
Animated version: Click markers 1 through 5 in order then markers 1 through 5 in order.
Pro: Overall low exposure to traffic Con: Tricky left turn in Factoria, extremely hazardous intersection at the end

• Get to the I-90 bridge eastbound.
• After crossing the bridge, stay on the trail when it twists under I-90; do not get off into the neighborhood. You will be on a trail parallel to SE Lake Rd (marker E1).
• You will reach a fork in the trail. Bear right and take the bridge.
• Ride through the park until the trail ends, putting you on 118th Ave SE (marker E2). Turn right (south).
• Hazardous crossing – busy street, look both ways: Immediately after the underpass, turn left to get back on the I-90 trail (marker E3). Note: hill climb.
• Turn left at Richards Road (marker E4).
• Immediately after underpass, turn right onto Eastgate Way (marker E5 = marker F1). Note: hill climb.
• Turn left at 161th Ave SE (marker F2).
• When the road ends, turn right onto SE 24th St (marker F3).
• Follow the road as it winds its way counter-clockwise around Phantom Lake; its name changes to 168th Ave SE and SE 16th St as it turns.
• Turn right onto 164th Ave SE (marker F4).
• Follow 164th Ave SE until it ends at NE 30th St (marker F5).
• Turn left and stop at Bel-Red Road.
• Extremely hazardous intersection. Cross Bel-Red, taking the back entrance to Microsoft main campus.

As with the blue route, you can avoid the hazardous intersection by taking a left onto NE 24th St. and turning right onto 156th Ave NE.

I haven’t tried any of these routes myself since I live on the north side of town, and if I need to head to Mercer Island, I start from my house, not from work. Still, these are useful routes to know, so I’m recording them here for reference.