top of page

Choosing a Hub

In this section we are going to outline how to pick out a Dynamo Hub that fits your bicycle. The important word here is Bicycle—this includes: custom cycles, Fat Bikes, small bikes, standard bikes, etc. If you are looking for a Dynamo that fits a: Trike, Folding cycle, Tandem cycle, or Cycle Trailer—you can likely just skip this whole portion as most of these products are Brand or Type Specific. If you have questions you can always just backtrack! 


Trike, Folding cycle, Tandem cycle, or Cycle Trailer: Next Page


(Richard Masoner "Supernova front hub dynamo" - Link - cc)

This will be the longest page of this entire guide. As much as we would like this to be easy, picking out a new Hub to fit your cycle involves a number of measurements you will need to make and component varieties you will have to identify which one your cycle utilizes. It is all pretty simple stuff however, you will need a caliper to complete this section. Therefore, we recommend it is easiest to bring your wheel into a bicycle store with us to get these. The list of measurements and connectors is as follows:

1. Axle Connector type

2. Axle width - thickness of the axle itself

3. Over Lug-Nut Distance (O.L.D.)

3. Spoke P.C.D / Flange Diameter

4. Flange to Flange Distance

5. Spoke Count, Size (gauge by mm)

6. Wheel Size or ISO Number 

7. Break Type

The goal for this section is to get measurements of your already installed Hub to reduce or eliminate the need to purchase new spokes depending on the amount of use the wheel you are modifying has seen. If you are modifying your daily rider or an older cycle and expect to be changing out the spokes, this can be done by just matching items: 1, 2, 3, 5, & 7 listed above. However, matching these precise measurements from 3 & 4 will still be of use as they will make it significantly easier to install your new Hub. If you find that measurements 3 & 4 on your cycle are not an exact match on your preferred Dynamo but match the other necessary criteria, that Dynamo will still work for you—but, you will have to replace all of your spokes. 

Axle Types

Axle Types


The Skewer named for its thin skewer like look, these come in 5mm thickness and 9mm or 10mm on some lighter duty mountain bikes or Fat Bike models. The skewer is made from two separate pieces containing a spring on one or both sides of the system. It looks something like this with a quick release (QR) on one side.


Thru Axle


(Glory Cycles - '#pivotcycles 16' Vault upgrades to F & R thru axles' - Link - cc)

With sizes from 10mm, 12mm, 15mm, or even 20mm—the Thru Axle is essentially a hefty metal rod with threads at one end and a torque lever or some kind of screw fitting (usually Allen wrench) at the other. If you have a Thru Axle, you will need to measure for which size Thru rod your bicycle has. As a quick note, there are currently no dynamos made for 10mm or 20mm Thru axles. 


(Glory Cycles - "Open U.P." - Link - cc)

Boost Axle (Thru Axle 2)

No photos provided because these essentially look the same, Boost axles are just extended Thru Axles that are made for wider O.L.D. (over lug-nut distance) cycles i.e. wider fork distance cycles. By adding 10mm to the total distance, changing from 100mm to 110mm O.L.D. measurement. Boost Axles wider stance improves the bracing angles to the wheel allowing for more stability during rougher rides. Boost axles are normally found on Mountain Bikes and have a handful of Hub Dynamo options available.

Bolt-On Axle

The Bolt-On Axle also doesn't need a photo because they look so similarly to the Thru Axle; however, the Bolt-On option has threads on both sides of the Axle and no quick release. Beyond this the Bolt-On axle sets itself apart by utilizing a series of nuts, washers, and bearings to attach it to the bicycle. Benefits to this axle type are in added stability and anti-theft attributes as bolted on wheels are much more difficult to take off.

Axle Measurements

Axle Measurements

The first thing you need to do before anything else is to determine what type of tire connection / Axle you have. There are a couple of different kinds supported by Hub Dynamos listed below laid out in this order:

(If you are using a Drum Break you may skip this section as you will be using a Bolt-On Axle)

Axle Type – Axle Thickness by width – O.L.D. (Over-Lugnut-Distance) Standard

Road Bike – “Skewer” Quick Release Skewer (QR) 5mm & 9mm front - 74mm & 100mm


Road Bike / Mountain Bike - Thru Axle 12mm & 15mm - 100mm


Mountain Bike “Boost” Thru Axle 15mm - 110mm


Fat Bike “Skewer” 9mm & 10mm Quick Release Skewer (QR)  - 135mm


Fat Bike Thru-Axle 15mm - 150mm


Bolt-On Axle unknown 9mm front / 10mm rear - 100mm 

The only unsupported axle sizes for any Hub that DynamoBicycle is aware of are: Fat Bike “Super Boost” Thru Axle 12mm by 157mm and various 10mm & 20mm Thru Axles rods of weird sizes like these custom axles below.


(Chris King Thru Axles - Edited, Cropped from original photo - Link - cc)

If you have either of these last few mentioned, then you likely will be sticking battery operated lights—as most of these are for intense mountain biking which does not produce high enough speeds for a Dynamo.


If you are still unsure your axle type you have then, below is a quick guide to figure out your connection. You will need a caliper to make these measurements. Go ahead and remove your tire to get to your axle in order to take the thickness measurement.  


Over Lug-Nut Distance (O.L.D.)

The next measurements you will need is the O.L.D. or Over Lug-Nut Distance, this is the distance between your down forks or the width of your Hub. Measuring your O.L.D. can be done imprecisely by measuring the distance between your down forks where the axle connects at once the wheel is removed. This will likely be a mm or 2 off due to the spring of the fork, especially on Skewer axle types. The true way to accomplish this would be to measure from the portion of Hub that touches the inside of the fork, to the same section on the opposing side. But measuring the inside of your fork will be close enough given that this measurement will be impossible to make the correct way on some wheels with the spokes still in.


Spoke Pitch Circle Diameter (P.C.D.)


Spoke Pitch Circle Diameter also referred to as Flange Diameter (not to be confused with Flange Distance)is the measurement from the center of one spoke hole on the outside of a Hub flange, directly across the the exact opposite spoke hole on the same outside flange. This can be a difficult measurement to make when your spokes are still inside of your Hub. However, knowing these average distances listed below, getting close once again should be sufficient to determine your P.C.D. Though given that many of these measurements are just 2mm apart, you will have to measure with as much precision as possible here. 

All Spoke P.C.D. measurements supported by Dynamos

  • 45mm

  • 52mm

  • 58mm 

  • 60mm

  • 62mm

  • 66mm

  • 67mm

  • 70mm

  • 74mm

  • 76mm (Bolt-on options only)

  • 89.9mm (Drum Break Hub)

  • 109mm (Drum Break Hub)

Shimano Alfine DH-S501 Hub with P.C.D of 70mm

Fange Distance

Flange to Flange Distance 

Referred to as Flange to Flange Distance, Flange Spacing, or Flange Distance. (Again, not to be confused with Flange Diameter. However, Hubs from the brand Shutter Precision as well as the brand Exposure call this measurement the Flange Diameter.) Whatever you call itthis measurement is preformed by measuring from the outside flange center of one spoke hole, across to the same point on the exterior of the opposite flange. With bicycle flanges usually not being straight up and down, usually being bowed or flared to some fashion—it is easy to mess up this measurement. However, unlike O.L.D. which is mostly universal & P.C.D. which can be altered as long as spokes length is also adjusted. Flange to Flange distances need to be within roughly 1-2mm of your current Hub's measurement. To assist you, below is a list of Flange Distances supported by our Dynamos to assist you.

All Flange Distances supported by our Dynamos


  • 44.6mm

  • 50mm

  • 51mm

  • 52.1mm

  • 53mm

  • 54mm

  • 56mm

  • 60mm

  • 62mm

  • 66mm

  • 68mm

Fat Bike Only:

  • 82mm


Drum Break Only:

  • 58mm

  • 58.1mm

  • 59.4mm


Shimano Alfine DH-S501 Hub with a Flange Distance of  52.1mm



Spoke counts are done in total by adding both sides together, 14 on one side and 14 on the other side means you have a 28 spoke hub and so on. Supported Dynamo spoke holes rims are 16/18/20/24/26/28/32/36 & two larger 40/48 designed for Tandem models.

Wikapedia Spoke Screenshot.png

(Wikipedia, Unknown author "Spoke Wrench" - Screenshot Section "Sizes" - Link - cc)

Gauge size 14 listed above is the most commonly used size for bicycles wheels and therefore, it is also the most commonly used spoke gauge for Dynamos as well. Most Dynamos don't provide spoke size specification due to this—some will provide mm measurements and some just specify as Gauge 14. If it doesn't say, then it is probably a 14. Exceptions to this is Gauge 13 which is normally specified as this is found more on specialty cycles: Folding Bikes, Tandems, and some others. However, some of these Hubs, like for Trikes are made brand specific and therefore, do not provide spoke measurements with their descriptions as they fit whatever size the brand wheels are made for.


Wheel Size | ISO #


Your ISO number is usually displayed in large print on the side of your rim of your tire, as seen photographed listed as "700x35C" on a 28inch tire. This is the American measurement for ISO number, the actual millimeter measurement is listed in fine print below this as "35x622"mm, the 622 being the European millimeter measurement. Some Dynamos use ISO #'s to identify size—therefore, these numbers combined with you spokes hole count can help you identify a proper sized Dynamo. If you don't have this listed on your rim, you can find your individual measurements via tire size in inches at this link here

Break Types

Break Type

There are 4 different kinds of breaks

  • 6-bolt Disc Brake

  • Disc Brake Type 2: “CenterLock”

  • Hub Brake / Drum Brake / Band Brake / Roller Brake / Servo Brake

  • Rim Break or V-Brake

You will need to know which of these you have pick out your Dynamo. Some Dynamos are made for 6-Bolt Disc brake only, some you will find are CenterLock only, and again some are V-break only. These difference between these is as follows.

Disc brakes come in two forms, the first is CenterLocks, these can be told apart from their 6-bolt counterpart as they have a separate toothed piece known as a "lock-ring" that houses the 6-bolts for your Disc. This attaches to your Hub via the jagged Locking circle on the outside of the spoke holes shown to the right in photo #1.

This is set apart from 6-bolt design where the Jagged CenterLock is replaced by 6-bolt holes actually a piece of the Hub where the Disk bolts too, show right in photo #2.

It is important to note that 6-Bolt and CenterLock Disc breaks are essentially the same thing and are interchangeable. The benefit to using CenterLock over 6-Bolt comes mostly in with the mounting being separate from the Hub itself—meaning that if a thread strips, a bolt breaks off, one of the mounts warp due to accident, etc. The Lock-ring can be discarded instead of the whole Hub. The downside is that CenterLock Hubs cost slightly more being comprised of two pieces and not just one. 

Next up is the V-brake (displayed as a booted CenterLock Hub) shown in photo #3. These are the most common brake type unitizing pads that clap down to the rim to slow the bicycle. For V-brake Dynamos, these are just simple no addition possible Axles. Though it is important to mention here that both CenterLock and 6-Bolt Hubs can be mounted on a V-Break Cycle. We will cover this concept in just a moment.

Finally, and probably the most uncommon brake type for a bicycle these days is the Drum Brake (No photo provided). Also known as: Hub Brake, Band Brake, Roller Brake, Servo Brake, etc. These are a tension based breaking system where the friction mechanism is inside the Hub, making these popular for wetter climates. Though requiring less maintenance than disc brakes, Drums breaks have gone out of style with the rise of the Disc break recently. However, there are multiple Drum Brake Dynamos on the market supplied by Shimano and Sturmey Archer. If you wish to learn more about these breaks, check out this page by Sheldon Brown Here.

Danger of Break etc.

Brake Conversion Warning

If one of these break types seems more useful to you than your present type—please DO NOT change it yourself! Always connsult with a professional to avoid potentially dangerous issues the average cyclist won’t know about. One of these issues is the extremely dangerous standard V-Brake fork Quick Release Skewer to Disc Brake conversion. This can cause your wheel to loosen & fall off from torque generated by the disc. This particular conversion requires something called a “lawyer lip” to hold the wheel skewer in place against the added torque from the Disc brake. 


Making Your Hub Go Further: "Future-Proofing

Two important options for those who think that they might want to change up their Cycle in the future or those who maybe have more than one cycle, fall under the concept of "FutureProofing". Essentially, this is a term defining the practice of investing in something with your future plans in mind. Hubs can be expensive, especially for the nicer ones. With options that allow you to use two different kinds of breaks or two different axle varieties as long you keep the same wheelbase size, this can potentially help cut costs in the long term by allowing you to use a single Hub in multiple places.


The first way of doing this, is the ability to use 6-Bolt and Center Lock Disc Hubs with V-Break designs. This doesn't work the other way around (For details here seen "Danger of Break Conversation" above) however; if you are currently riding a V-Break, picking up one of these Disc Break varieties opens the door to usage down the road if you ever change up your cycle.

 In addition to crossover from break types, there are also many adapter options to fit: 15mm Thru Axles to 12mm Thru Axles, and both to Quick Release (QR) Skewers.  The brand Kasai even offers a 15mm Thru Axle 6-Bolt Disc 100mm O.L.D Hub to 14mm Thru Axle 6-Bolt Disc 110mm O.L.D Boost conversion kit. (Though it is unknown at this time if this will work with other brands / adapters or any CenterLock Hubs.) Allowing you to switch out your wheel on various axle types to fit your potential needs. These options will be listed on our Mounting Hardware page after picking a hub in "Your Hub Options" . 


It is worth noting that there are many different axle sizes and adapters. Due to this we suggest that anyone going this route please double check your own axle, the hub you are ordering, and the adapter before placing your order. 

Notes & Other Info

Notes & Other Info

Improving Ride Feel

As we talked about in our segment about drag on the previous page, some Dynamos can lightly be felt through the bike while riding. It has been noted that crossed-laced spokes vs. radially-laced spokes can reducing this. The effect being similar to plucking a string on an instrument without touching it vs. holding a note on that string while plucking it. By giving your spokes cross points, this limits the vibration distance and changes the way these vibrations are transmitted to the rest of your cycle.

Radial vs. Cross Laced.jpeg

Adjusting Bearings

Radial Lace (Left) vs. Cross Laced (Right)

Dynamos can be felt easier at lower speeds than at higher speeds, where the feeling of their operation smooths out. This sometimes makes people think that their Hub Bearings are somehow unaligned or too tight when they give their tire a test spin. This is not the case at all, what you are feelings is simply the higher drag at lower speeds effect. Attempting to adjust the bearings has been cited as one of the first and foremost causes of broken Dynamo units only second to water damage. It should also be noted here that any attempt to open the Hub to fix this will instantly void your warranty for any Dynamo besides the Kasai serviceable Dynamos, who have replaceable bearing sets due to the exposed nature of their "Field Serviceable" or FS series Hubs.

Hubs Issues with Wireless Bicycle Computers

Magnets don’t like other weaker magnets. So, when we tell you that there are old reports of Dynamos affecting wireless bicycle computers—this shouldn’t come as much of a surprise. Most these reports are a couple years old and this doesn’t seem to be as much of an issue in recent years. Although, if you are finding this to be an issue or are purchasing a new bike computer alongside your new Dynamo Hub—it would be best to grab a wired model to avoid potential interference.


Roll With It - An Important Warning for Mounting

Many Dynamos are screwed together a specific way, be it counterclockwise or clockwise—whichever way it may be, these Dynamos are designed to roll in the same direction they are screwed together and need to be installed as such. As like anything screwed together, no matter how tightly, it can come unscrewed. This doesn’t mean that you can’t roll backwards or anything ridiculous. It just means that for regular usage that the Dynamo should be mounted to roll with that torque, less the bumps and high speeds slowly loosen and inevitably break your generator.


Brands that have potential for this to happen should provide this direction in the mounting instructions for your Dynamo. In the case of the brand Shutter Precision, you will find notes in the instructions informing you too install with the arrows on the Hub pointing the direction the wheel will roll. This can be seen in the SP 8X Series instructions here.


A brand that we have also seen warnings for online is SON/Schmidt regarding the Dynamo model SON28 or SON20 as it was known back in the day. Stating that this has to be mounted with the plug facing to the right side of the bicycle. How to determine which side is the right side, is unknown to us at this time. Son/Schmidt instructions for their Dynamos are not listed online like SP’s so, this is important to remember if looking to buy a SON/Schmidt Dynamo Hub as we don’t know if this is contained within their instructions.


As DynamoBicycle accumulates more information on these products we will add mounting direction information to the various brands and listings for the Dynamos we are sponsoring. Until then, please double and triple check before mounting and for Disc brake users—check before purchasing to make sure your brakes are on the correct side!

Next Up

Next Page

From here, there is one last important stop to make before choosing products. This next portion covers: Power Output varieties for Dynamos, how these varieties function in relation to speed, and the input requirements of various system additions paired with these Dynamo output options. Keep in mind your measurements from this page and add in what power requirement you think you will need from the next page—then we will view a list of potential Dynamo Hubs that fit your needs!

bottom of page