What Spoke Length Do I Need? 5 Steps to Building Your Own Custom Wheels

Words by: Max Morgan

A common question we receive all of the time is, 'What spoke length do I need?" If you are someone interested in building your own custom set of wheels, we are here to walk you through the 5 steps to do just that. If you are eager to build up a set of mountain bike wheels with your favorite hubs from Industry Nine or DT Swiss, how do you know what length spokes to use? How do you find the most important rim dimensions? You can build up your wheels in a 1 cross, 2 cross, or 3 cross spoke lacing pattern, but which pattern should you use for your particular wheels? We are here to answer all of these questions and more, that way you can build up your dream wheelset!

1.) Hub Shell Dimensions 

When it comes time to piece together your wheelset, you will want to know what hubs and rims you will be using before you know the appropriate spoke lengths you will need. To start, we are going to dive in to the dimensions you will need to take from your hubs. Most all manufacturers will have engineering drawers available online so you can pull all of this important information. 

• Flange Diameter: The hub flange is outermost lip of the hubshell that the spokes hook in to. In the graphic above, A references the diameter of the non drive side flange and D references the drive side flange. With a tradition J-bend spoke, the spoke is fed through the flange of the hub and then secured by the spoke nipple at the rim. Keep in mind that the flange diameters of the left and right side of both the front and rear hub can all be different dimensions. 
• Left Flange to Center and Right Flange to Center: Where each hub flange lies in relation to the center of the hub shell is also very important for determining spoke lengths. In the graphic above, B measures from the center of the hub to the non drive side flange. C measures from the center of the hub to the drive side flange. Each manufacturer uses a different design for their hub sets and this measurement will be different for each hub. The left to center and right to center measurements not only change between manufacturers but also between hub widths. Obviously if you are using a 148mm rear hub, both of the flange to center measurements on a 157mm width hub are going to be different.  
• Front and Rear Hubs: It's important to remember that both the flange diameter and flange to center measurements can be different between the front and rear hubs. Be sure to keep this in mind when searching for this information for your particular hub model. 
• Spoke Count: The last thing to remember when building up your new wheelset is the spoke count for your hubs. When it comes time to ordering your hubs, rims, and spokes, you want to be sure that both the hubs and the rims use the same number of spokes. A majority of mountain bike wheels use either 24, 28, or 32 spokes per wheel depending on their intended use. 

2.) Rim Dimensions

Now that we have all of the dimensions necessary for both your front and rear hubs, let's figure out what dimensions we need from the rims themselves. Because rims come in all different sizes, shapes, and styles, wheel and rim manufacturers generally publish all of the most important dimensions for their rim design. If you are having trouble finding the your rim's ERD (Effective Rim Diameter) and spoke offset, don't hesitate to give us a call here at Worldwide Cyclery, and we can get you squared away!

• ERD (Effective Rim Diameter): The rim's ERD or Effective Rim Diameter is measured from where the spoke nipple is seated on one side of the rim to the exact same location straight across the rim. In the graphic above, you can see the cross section of one rim or hoop. 99% of all rim manufacturers publish information on the rim's ERD measurements, but the ERD can also be measured by hand as well. This can sometimes be helpful when building a rim and hub combination you have not worked with before. The ERD can be measured using a set of Park Tool DC-1 digital calipers, two nipples and two spokes as essentially measuring sticks. If you are having trouble finding what your rim's ERD is, feel free to give us a call at the shop. 
• Spoke Offset: Not all rims have the spokes aligned directly on the center line of the rim. Because the hub center to flange measurements are different from the drive side to the non drive side, the spoke bracing angle on each side of wheel can be slightly different. To help combat that and in turn make it easier to build the wheels with equal spoke tension from one side to the other, rim manufacturers often offset the spoke holes to one side of the rim. Some rims feature a 0 mm spoke offset, while others might feature a 3mm spoke offset for example. 
• Spoke Count: Just like we said before, it's important to make sure the spoke count for both the hubs and rims are the same. If you are looking for a specific rim that for example is intended for downhill use, you may be limited to only one spoke count option. When it comes to hubs, the same hub shells are usually offered in multiple spoke hole options. 

Zipp 3ZERO Moto wheels feature a unique moto inspired single wall rim with a 0mm offset design

3.) Radial vs. 1 Cross vs. 2 Cross vs. 3 Cross Lacing Patterns

For the most part, there are four different lacing patterns primarily used in cycling. Each of the different lacing patterns, radial, 1-cross, 2-cross, and 3-cross, have their own pros and cons. In general, most wheel builders refer to a 3-cross pattern as the standard lacing pattern for mountain bike wheels. When it comes time to build up your own custom wheels and you can't decide which lacing pattern best suits your build, give us a call at the shop and ask for Liam. Liam is the head mechanic at our California location and is a wizard when it comes to building wheels. Keep in mind that different lacing patterns require different spoke lengths. 

• Radial Pattern: A radial lacing pattern, often referred to as 0-cross, sees each spoke move from the hub to the rim without crossing another spoke. Radial lacing patterns are commonly used on the non drive-side of road racing wheels. Because each spoke goes directly from the hub to the rim, the radial pattern uses the shortest and therefore the lightest spoke possible for a given wheel size. The radial pattern can be also be seen on rim brake road wheels. 
• 1-Cross Pattern: Just like it sounds, the 1-cross pattern is where a particular spoke only crosses one other spoke from the hub to the rim. One cross wheels are stereotypically built just as much for aesthetics as they are for weight savings. You can find a 1-cross pattern on handmade bikes that aren't designed to be ridden hard like you would a gravel bike or mountain bike.   
• 2-Cross Pattern: A 2-cross pattern provides slightly more stiffness than a 1-cross, while still giving you minimal weight savings over a 3-cross. A 2-cross pattern can be found on 24 hole mountain bike and cycle cross wheels. 
• 3-Cross Pattern: Most mountain bike wheels are all built on a standard 3-cross lacing pattern, where a single spoke crosses over three others spanning from the hub to the rim. A 3-cross pattern is one of the strongest ways to build a bicycle wheel and is common for 28 and 32 hole mountain bike wheels. 

4.) Spoke Length Calculator 

Now that you have all of the different hub flange diameters, hub center to flange measurements, the rim's ERD, the rim's spoke offset, and the spoke count, the best way to determine the spoke lengths needed for your wheels is to use a spoke calculator. We are big fans of the QBP spoke calculator in particular. It's simple, easy to follow, and gives you a breakdown for different lacing patterns. Plug in all of the correct dimensions and the spoke calculator will spit out the necessary spoke length for both the non drive side (left) and drive side (right). Because the dimensions on the front and rear hubs may be different, remember to fill out the spoke calculator for both the front and rear wheels. 

5.) What Spokes and Nipples Should You Use? 

Now that you know how you are going to lace your new wheels and what spoke lengths to use, it's time to choose which spokes and spoke nipples best fit your build. DT Swiss is without a doubt the industry leader for spokes for all different bikes. DT is your one stop shop for not only spokes, but they also offer four different spoke nipples dedicated for different applications. First it's important to understand the different types of spokes that are out there. Let's break down the difference between straight gauge spokes, single butted spokes, double butted spokes, aero bladed spokes, and straight pull spokes. In the illustration below, you can see an example of a double butted spoke. 

• Straight Gauge Spokes: Straight gauge spokes are the same gauge or width the entire length of the spoke. A majority of straight gauge spokes are 2mm or 14 gauge and are used on bmx or mountain bikes where saving weight isn't your primary concern. Because these spokes are all the same thickness, they provide a bit more stiffness and are cheaper to manufacturer. Example - DT Swiss Champion.
• Single Butted Spokes: Single butted spokes feature a thicker section at the neck of the spoke, closest to the hub. This gives the wheel additional strength, an even stiffer feel, and is best used for heavy duty applications. Single butted spokes are generally heavier than straight gauge and double butted spokes. 
• Double Butted Spokes: Double butted spokes taper down in the middle of the spoke, reducing wheel stiffness without compromising overall wheel strength. Sometimes a wheel that is as stiff as possible isn't the best thing. Having a wheel that is more compliant helps the bike track the ground, giving you more grip. Double butted spokes are lightweight and typically more expensive to manufacturer. Example - DT Swiss Competition, DT Swiss Competition Race. 
• Aero Bladed Spokes: Bladed spokes are designed to be more aerodynamic, allowing the spoke to cut through the air. Bladed spokes feature a flattened middle section that runs a majority of the length of the spoke and are commonly found on road and time trial bikes. Example - DT Swiss Aerolite, DT Swiss Aero Comp.
• Straight Pull Spokes: Straight pull spokes do not feature the same traditional J-bend hook at the end of the spoke but instead a straight flange. Straight pull spokes require a dedicated straight pull hub and are designed to eliminate the weak point on the hook feature on a standard J-bend. Most all DT Swiss spokes are also offered in a straight pull option. 

Let's Build Up a Set of Wheels as an Example

So here we go. I am in the process of building up a set of wheels for my own Santa Cruz V10, and so I figured this would be a good opportunity to walk you through the process. I know that I will be using Industry Nine Classic hubs and Santa Cruz Reserve DH 29" rims. First thing we need to do is go and track down all of the necessary information mentioned above for this particular hub and rim combination. Keep in mind that every rim and hub combination is different.

The Fox 49 fork on this bike uses 110mm boost spacing. Find the right information for your particular fork

The Santa Cruz V10 we are looking at here uses 157mm rear hub spacing. Make sure you know the rear hub spacing on your bike

Here is a breakdown of all of the dimensions for each Santa Cruz Reserve rim offering pulled from Santa Cruz's website

Now that we have all of the appropriate information for our Industry Nine hubs and Santa Cruz Reserve DH 29 rims, we can starting plugging that information in to the QBP spoke length calculator we mentioned before. Looking at the front wheel first, the non drive side (NDS) flange measures 58mm and the drive side (DS) flange measures 45mm. The NDS center to flange measures 27mm and the DS center to flange is 42mm. The Santa Cruz Reserve DH 29 rims have a 594mm ERD and feature a 3mm asymmetrical offset. Because these wheels will be ridden on a downhill bike and are guaranteed to see plenty of abuse, I will be using a standard 3-cross lacing pattern. You can see highlighted in blue in the photo below that this hub and rim combination for the front wheel calls for a 288mm J-bend spoke on the non drive side (left side) and a 291mm J-bend spoke on the drive side (right side). 

Now looking at the rear wheel, the non drive side (NDS) flange measures 58mm and the drive side (DS) flange measures 60mm. The NDS center to flange measures 41mm and the DS center to flange is 29mm. The Santa Cruz Reserve DH 29 rims have a 594mm ERD and feature a 3mm asymmetrical offset. I will of course use the same 3-cross pattern on the rear wheel as well. You can see highlighted in blue in the photo below that this hub and rim combination for the rear wheel calls for a 289mm J-bend spoke on the non drive side (left side) and a 288mm J-bend spoke on the drive side (right side). 

Now that we know exactly what spoke lengths to buy, all we need to do is decide which spokes and nipples to use. Because this is a high end mountain bike wheelset, I have decided to use double butted spokes, the DT Swiss Competition Race spokes in particular. The Competition race spokes feature a 2.0 - 1.6 - 2.0 profile compared to the 2.0 - 1.8 - 2.0 on the standard DT Competition spokes. Because the carbon Santa Cruz rim is very stiff, having a lighter spoke will give the wheels a bit more compliance and better feel over trail terrain. For spoke nipples I have decided to go with the DT Swiss Squorx Pro Head spoke nipples in aluminum. I hope that walking through this process has helped you understand the process of building up your own custom wheels and deciding what spoke lengths you need for your build. 

This article was written / authored by Max Morgan. Max has been a professional downhill mountain bike racer for the last 10 years, competing in the UCI World Cup downhill series and U.S. Pro GRT series. Having ridden all different kinds of bikes on trails all over the world, Max's experiences being out on the circuit give him a unique perspective on what makes for a quality cycling component. Max also has degrees in Mechanical Engineering and Physics, and so if you don't see out on the trail, chances are he is probably in the garage tinkering on the next project.