Carbonal Carbon MTB Rims
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road bicycle 38mm clincher rims

700C road bicycle U shape 25mm wide 38mm deep clincher rim tubeless ready

Item RX38SH, weight 470g, ERD 569mm. Wider, stronger and faster. This road 38mm deep clincher rim is 25mm wide. The wide rim profile offers improved aerodynamics, better handling in crosswinds condition and faster riding.

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650b bike rim

Asymmetric rim profile 29 inch mtb rims carbon hookless tubeless ready

Item MX932XC, weight 350g, ERD 595mm. This asymmetric 3mm offset 29er mtb rim balances drive and non-drive side spoke tension to create a more durable and well-balanced light mtb wheel, it's perfect upgrade for your xc mountain bike.

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Enduro 27.5 carbon rim

Enduro 27.5er mountain bike hookless 35mm wide carbon rim tubeless ready

Item MX735EN, weight 440g, ERD 560mm. This enduro 27.5er carbon rim is enhanced version base on trail 35mm wide rim, more stiff, durable and long lasting, which is perfect for all mountain and enduro mountain bicycle.

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gravel bike carbon rim

High performance 29mm wide 28mm deep 29er carbon rim for gravel bike

Item GCX28, weight 380g, ERD 589mm. This 3mm asymmetric 29er carbon rim is the best choice for lightweight gravel bike wheel. It's tubeless ready, compatible wider tire for comfortable ride, accompany you to conquer the rugged terrain.

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disc brake tubular rim

Disc brake 38mm deep lightweight carbon road bicycle tubular rim

Item DT38S, weight 330g, ERD 569mm. Wider and U shape 38mm deep aero designed rim profile, constructed with premium Toray T700 & T800 carbon fiber, makes this disc tubular rim super light, a good choice for lightweight road wheels.

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asymmetric disc rim

Asymmetric 50mm depth disc carbon rim U shape clincher tubeless ready

Item DX50D, weight 450g, ERD 545mm. Asymmetric rims with offset nipple bed benefit to overall wheel strength by proper balancing of the spoke bracing angles from one flange to the other, build into a lightweight but strong road disc wheel.

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road disc rim

Aero road gravel bike carbon rim 28mm wide 38mm deep clincher tubeless

Item DX38L, weight 410g, ERD 569mm. Featuring a wide 28mm external rim width, this tubeless ready 38mm clincher rim set offers a wide and stable platform for everything from road bike to gravel bike tires.

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trail bike rim

Asymmetric 37mm wide 29 inch trail bike rim hookless tubeless ready

Item ASD937TR, weight 420g, ERD 595mm. This 29 inch carbon mtb rim with asymmetric 3.5mm offset profile, wider rim width 37mm external and 30.6mm internal can fit 2.3"~2.6" (recommended) mtb tires.

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2019 Eurobike booth A1-212, welcome to visit us!

2019 Eurobike booth A1-212, welcome to visit us!

Dear All, We are glad to invite you to visit our booth in the coming Eurobike bike show 2019 - the world`s leading trade fair for the cycling industry. Booth no.: A1 Hall, 212 stand (A1-212) Date: Sep...

Effective Rim Diameter (ERD) and Spoke Length

2017-05-08

When building a bicycle wheel, the Effective Rim Diameter (ERD) of rim is an important measurement used to calculate the correct spoke lengths. It is very important to know that the ERD we list. Below is information on how to properly calculate ERD, and ERD values for our carbon Rims.

What is ERD - Effective Rim Diameter?

At Carbonal we use the technique defined on Sheldon Brown's website to measure ERD.  That technique is defined as follows:

Effective Rim Diameter (ERD) is the diameter on which you want the ends of the spokes to lie, we calculate from the top point of the nipple.

The corresponding equation and a representative figure for that definition are as follows:

carbon rim ERD calculation

                                    ERD = A + 2B


If you want to measure your own rim (recommended, just to be sure), then follow these instructions:

--1. Insert two old spokes into holes exactly opposite each other on the rim. Count holes to be sure.

--2. Screw some nipples onto the spokes.

--3. Pull them tight and measure dimension A in the figure (the diameter to the edge of the nipples, where the spokes disappear into them). Do this at several spots around the rim and average the measurements.

--4. Measure the length of a nipple (dimension B in the figure) and add it twice (once for each nipple). The result is Effective Rim Diameter (ERD).

--5. ERD = A + 2B.

As you can see from the figure, if you use different nipples then we use at Carbonal, your ERD value could be different.  As a result, we recommend that you always measure your own ERD value before building your wheels.  For more specific information on how to properly complete the measurements above, we suggest you thoroughly read through Sheldon Brown's website, or take your wheels to an experienced wheel builder.