Front Wheel Retention Systems: What Do You Need?

by robhoward on June 14, 2009

With Three Different Options to Choose From, Bikeskills Gives You Some Advice On What Will Best Suit Your Bike and Application.


L to R: 9mm Quick Release, FOX/Shimano 15QR, 20mm Through Axle. Read on to find out what’s right for you.


Mountain Bike Wheel Retention Systems in Review

While there are various accounts of the history of the quick release, it certainly dates back to around 1927 and was invented by Tulio Campagnolo for road bikes, specifically to allow rapid wheel changes (primarily to repair flats).  While there have been myriad variations of the basic quick release mechanism, the basics (which many feel are problematic for mountain biking applications) are unchanged.

20mm Through axles came on the scene in the late 1990s. The first applications of Through Axles (also spelled Thru-Axle) were on downhill and freeride forks, including Rock Shox’s Boxxer and Marzocchi’s “T” series forks. While there is no true (such as a JSO, ECMA, ASTM, etc.) standard for 20mm through axle forks and hubs, because the hub “spacing” is agreed to be 110mm, virtually all 20mm forks accept all 20mm hubs. However, the fork and axles are proprietary as are their closure mechanisms (FOX, Rock Shox, Marzocchi each have their own, non-interchangeable systems)

The newest front wheel retention system, the Shimano-FOX 15QR, is an attempt to combine the benefits of a light weight QR system and the reliability and stiffness of the motorcycle inspired 20mm through axle. While the 15QR is a so-called Open Standard (other manufacturer’s have free access to the technical details) to date,  only FOX is making 15QR forks.  Bikeskills believe that 15QR is the best overall retention system for trail-to-all-mountain bikes and applications. Whether or not the 15QR is widely adopted by other suspension manufacturers remains to be seen. However, given the extensive engineering and testing capabilities of both FOX and Shimano, Bikeskills feels that the 15QR retention system is both safe and effective.


Quick Release Pros:  Light. easy and intuitive to operate. Universal standard. All QR Hubs and Forks are Interchangeable. Despite Concerns, failures are very rare. Hub’s axle Acts as primary wheel retention, QR as back-up. Works with all roof and other bike racks.

Quick Release Cons: If the lever (cam) is not closed, wheel can Separate from fork. Due to small diameter skewer and slots in drop-outs, QR forks exhibit the most flex.Under heavy demands (such  as jumping) QR fork tabs can shear off. People have been injured when improperly fastened QRs resulted in front wheel separation. 

Primary Applications: Road, Hybrid, XC and Trail Bikes.

Travel Range Available: Rigid and generally 80mm to 140mm.


15QR Pros: Relatively light (adds about an ounce over std QR). 15mm hollow aluminum axle is stiffer and stronger than std QR. Fork drop-outs are not slotted (which weaken fork/hub interface)  as are QR forks.

15QR Cons: Limited number of hub suppliers (as of June 2009). Long-term reliability to be determined. Not yet a true standard (open std status by FOX/Shimano). Neither as strong or as tested as conventional and more widely used 20mm “through-axle” design. Require special adapters for most bike rack systems.

Primarly Applications: Trail bikes, all mountain bikes, light duty Jumping, speciality competition such as dual slalom, Super D.

Travel Range Available:  Currently 100mm to 150mm


20mm Through Axle Pros: Stiffest std axle and retention system in mountain biking. Axle is 20mm in diameter. Most secure wheel retention system in mountain biking. Most robust fork dropouts. Wider “stance” allows wider tires to be used (up to 3″)

20mm Through Axle Cons: Heaviest wheel retention system. Some 20mm retention systems are complicated. Inconsistent, non-std closure mechanisms. Some systems require “tools” to remove axle and Wheel. Most roof racks due not accept 20mm forks without special adapters. Heavier, wider hubs and axles.

Primary Applications:All heavy-duty mountain biking including long-travel freeride and downhill, dirt jumping and “Slopestyle” riding.

Travel Range Available: 100mm to over 200mm


Some Selection Guidelines:

As should be obvious, there’s a fair degree of overlap in fork retention systems. This is especially the case with trail and all mountain bikes and riding, which is what most of us do, and what the bulk of Bikeskills clinics and events cover. Still, there are some general guidelines. Additionally, if you think you’re in a gray zone, we strongly recommend choosing the more robust of the systems. While you may add an ounce or two to your bike, remember what they say about the ounce of prevention being worth more than a pound of cure!

Light Duty Cross Country and Trail Riding and Bikes

We don’t want to sound alarmist and suggest that everyone needs to discontinue riding their standard QR equipped bikes. In fact, if you are a cross country racer, there’s little chance, especially if you are 160 lbs or less, that you’d even consider doing so. Literally tens of millions of mountain bikes have been raced, ridden hundreds of millions of miles with very few problems. With that in mind, if you are a relatively light rider, riding mellow trails, such as fireroads, moderate single track, and or racing, QR forks from makers like Fox should be just fine. However, we strongly recommend frequently checking the fork’s dropouts for any signs of fatigue, cracks, etc. and always make sure that your QR mechanism is in good shape and securely fastened. And while Ti skewers might sound like a great way to loose 10 grams, keep in mind that Titanium has a lot more flex than does CroMoly steel (in other words, you’ll save weight with a Ti skewer and introduce flex and less steering control, especially in the rough stuff…) We recommend that if you are looking at forks with 140mm or more travel, are heavy, ride technically demanding conditions, you look at 15QRs and even 20mm Thru-Axle designs.

Trail And All Mountain Bikes and Riding

We’re not sure who came up with either term, Trail or All Mountain Bikes, but we wished that they would have at least written up a spec!  Since they did not, we will… sort of. When Bikeskills refers to a trail bike, we’re talking about a dual suspension, medium duty bike with between 100mm and 140mm travel front and rear. Trail bikes are what most people seem to be buying these days, especially in the higher end of the market. A good trail bike can be used for an endurance race just as easily as it can make down some pretty demanding trails like those found in Downieville, Moab, etc. And because more and more people are pushing the limits of trail bikes, we feel that many trail bike owners should seriously consider the new 15QR forks and wheel hub systems. And if you’re a Clydesdale (over 200 lbs) on a trail bike, riding it hard, you should think about one of the lighter 20mm Thru-Axle forks.

All Mountain is the next step up and is seems that most people agree that an All Mountain Bike has roughly six inches of travel front and rear. Likewise, sacrifices that give a nod to weight over toughness on a trail bike go in favor of extra beef on an All Mountain Bike. All Mountain Bikes often have extra head tube gussets,  heavier-wider rims, tires ranging from 2.3- 2.5 inches, etc. This is the bike – and application – that we feel deserves at least a 15QR fork and if you are over 180 lbs or so, use the bike for jumping, light freeriding, etc. do yourself a huge favor and get a 20mm Thru-Axle fork and wheelset!

Speciality Applications: 4X, Dual Slalom, Mountain Cross, Light Duty Jumping, Pump Tracks…

This is probably the toughest bike and application to make a recommendation for. And if you are a speciality racer, hard core jumper or pump track star, you surely know what you are doing and need. That said, FOX’s new 15QR forks provide many specialty gravity racers and pumpers with another options, especially for lighter riders, and or when a course is less demanding and weight matters. Our recommendation is: call the pros at Fox and ask them what they recommend for your specific situation. If you are in doubt, get a 20mm through axle fork.

Freeriding, Downhill, Park Riding, and Dirt Jumping

Fortunately there are no decisions necessary for mountain biking’s most demanding riding applications, bikes or forks: all long travel forks are now 20mm Thru-Axle designs. While this was not the case a few years ago, it is now. So if you are buying a new fork and or bike, that’s what you’re going to get. As for buying an older, QR style long travel (more than 150mm) fork, don’t even think about it!


If you’re riding something like this 100mm travel, $6K beauty, then you are probably shaving weight wherever you can. And as long as you’re not too heavy, and are using the bike as the cross country racer it is, a QR fork should be just fine. Keep in mind that FOX does manufacture its lightest F-Series forks in 100mm and 120mm travel with the new 15QR retention system.


Here’s where the choice gets a bit tricky… The Santa Cruz Nomad has 6″ of travel and is truly a “go anywhere, do anything” bike. The problem is that if you’re going up big hills to get to equally big downhills, you better have a sturdy, long-travel fork…. but then again, you have to haul it up. What to do? We recommend at the very least you sport a 15QR fork and hub. But if you’re heavy, and or ride heavy duty fare, step up to a 20mm set-up.



No doubt about this one! If you are lucky and tough enough to be riding a Santa Cruz V-10 with 8″ of travel in front and 10″ in the back, then there’s no choice: 20mm thru-axle retention system. You’ll also more than likely have a “double crown” fork like Jiro here on Santa Cruz Bicycles Founder Rob Roskopp’s personal bike.


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