All Trek Bikes are now shippable! | Shop Today

Check HSA/FSA eligibility with Truemed | Learn More

12-Month Financing with Synchrony | Learn More
Specialized Gear Up Summer Sale
Shimano

Shimano Dura-Ace Di2 SM-EW90 5-Port Junction Box

$155.00
SKU: ISMEW90B  |  Barcode: 689228986398
Color
Type
Pickup
Pickup in store
Ship
Ship to home
Learn More About Delivery Options

What is the Bike Mart Return policy?

Bike Mart offers a 14-day return and 30-day exchange policy in effect on qualifying items. Restocking fee may apply for "At Warehouse" Items. Read More

What Financing options does Bike Mart offer?

Financing is easier than ever at Bike Mart. With Synchrony Financial, you can choose:

  • 0% APR for 6 months — on orders under $999
  • 0% APR for 12 months — on orders of $1,000 or more

We also support HSA/FSA Funds with TrueMed, Shop Pay Installments and PayPal Financing.

Overview
When the Shimano Di2 E-Tube wires exit the Di2 brake/shift levers or the Di2 bar end shifters, they need to go somewhere to attach to the Di2 system.  That somewhere is the SM-EW90 Junction Box. 
Sometimes called Junction A, or seen as the connection box sitting under the stem, this is where the wires need to be plugged in to give directions to the front and rear derailleurs and get electricity from the battery.  It also is how you charge Di2 batteries while leaving them on the bike.
There are two versions of the Junction Box.  SM-EW90-A is the three-port version.  SM-EW90-B is the five-port version. 
Three ports is the minimum.  This represents a wire coming from one shifter, a wire coming from a second shifter, and a wire going to the junction box, aka junction B, by the bottom bracket.  With three ports, you can either run shifting from the brake levers or the bar ends (aka aero bars).  You can't do both.  If you want the option to expand your system at all, the five-port box is probably the better choice.  That, or you'll upgrade to the five-port box when you expand your system.  However, if you're looking to add Sprinter Switches (SW-R610) or Climber Switches (SW-R600), these plug into the ports on the drop bar integrated levers, so you don't need the five-port box if you think you'll go this route.
The Junction Box comes with mounting plate as well as two rubber straps to affix the box to your bike.  The box also has a port for on-bike charging of Di2 batteries and reprogramming and updating your system.
The Shimano Di2 SM-EW90 Junction Box gathers the shift wires before they communicate with the derailleurs.

Why Shop at Bike Mart?

  • Live Chat with Real People

    Get instant advice and answers from our team of cycling experts through our online chat feature or over the phone.

  • Community-Focused

    We have donated over a million dollars to support our communities through charity rides, bike rallies and advocacy for more bikeable trails in Texas.

  • Professional, Quality Assembly

    Our bikes are expertly assembled and inspected by Bike Mart’s professionally trained staff. They ensure proper adjustments, tighten and true wheels, and get your bike ready to ride.

  • Our Legacy of Excellence

    With 62 years of retail experience, Bike Mart brings unparalleled expertise and dedication to serving you.

  • 10% off accessories with new bike purchase

    Receive 10% off all accessories purchased with a new bike.

  • Hassle-Free Returns

    Easily initiate returns for online orders with our straightforward return policy to shop with confidence.

  • Locally Owned & Operated

    A family of cyclists who live and ride in your community—feel right at home.

  • Free accessory installation with new bike purchase

    Let our experts install your accessories at no extra cost, ensuring everything fits perfectly and is ready for your ride!

product
Shimano

Shimano Dura-Ace Di2 SM-EW90 5-Port Junction Box

$155.00

When the Shimano Di2 E-Tube wires exit the Di2 brake/shift levers or the Di2 bar end shifters, they need to go somewhere to attach to the Di2 system.  That somewhere is the SM-EW90 Junction Box. 

Sometimes called Junction A, or seen as the connection box sitting under the stem, this is where the wires need to be plugged in to give directions to the front and rear derailleurs and get electricity from the battery.  It also is how you charge Di2 batteries while leaving them on the bike.

There are two versions of the Junction Box.  SM-EW90-A is the three-port version.  SM-EW90-B is the five-port version. 

Three ports is the minimum.  This represents a wire coming from one shifter, a wire coming from a second shifter, and a wire going to the junction box, aka junction B, by the bottom bracket.  With three ports, you can either run shifting from the brake levers or the bar ends (aka aero bars).  You can't do both.  If you want the option to expand your system at all, the five-port box is probably the better choice.  That, or you'll upgrade to the five-port box when you expand your system.  However, if you're looking to add Sprinter Switches (SW-R610) or Climber Switches (SW-R600), these plug into the ports on the drop bar integrated levers, so you don't need the five-port box if you think you'll go this route.

The Junction Box comes with mounting plate as well as two rubber straps to affix the box to your bike.  The box also has a port for on-bike charging of Di2 batteries and reprogramming and updating your system.

The Shimano Di2 SM-EW90 Junction Box gathers the shift wires before they communicate with the derailleurs.

Color

Type

  • 5-Port
View product