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As more and more manufactures release disc versions of popular road frames, I am seeing more and more road bikes with 12mm thru axles. I was wondering if there is a reason for not just doing away with quick-release and converging the disc and rim versions of very similar models, say the '18 BMC team machine which has identical geometry for both rim and disc for instance, to both use a thru axle.

I know the wheel change speed argument against the thru axle, in so far as it can take longer to pop out a wheel to replace it in a race. Aside from this, and looking at a more comprehensive view that takes into account non-racers, is there a reason to not equip all road bikes with through axles?

The arguments for are compelling; a stiffer, more secure front end being the main. While this is more important when dealing with asymmetric torque from a disc rotor being applied to the hub, I think it is still valid and likely beneficial without disc brakes. Granted, I have never ridden a thru axel bike that wasn't a disc, it seems like it would be superior even with rim brakes.

Are there any reasons not to build road bikes with through axels, even if they are not disc brake equipped? Is this a trend we might see as manufactures produce more pairs of very similar road disc/non-disc models?

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  • Wheel change speed is a huge consideration, it's not a negligible difference either. It's not something to discount
    – Rider_X
    Commented Jun 25, 2017 at 14:15
  • @Rider_X I agree but, when was the last time you needed to change a wheel "fast". It's not that slow to take an axle out. Also, RAT, rapid axle technology, and others make it pretty painless. Again, I realize I'm not speaking for someone riding in a pro peleton. So if one can put that aside, I'm interested in the viability. Also we are seeing discs anyway in peletons, with thru, that have to be changed, so is it a moot point?
    – ebrohman
    Commented Jun 25, 2017 at 14:32
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    Road bike industry runs on people who LARP pro peloton.
    – ojs
    Commented Jun 25, 2017 at 16:32
  • Last wheel change would be a crit. With laps under 1 min, you have to get to neutral support then swap the wheel, set the brakes and get back into the group when it comes around. In this instance every second counts. Plus rim caliper brakes are much quicker to adjust to a new wheel than disc brakes which require moving the caliper or shimming out the rotor. In everyday riding, the speed cost of thru-axels is non-existent.
    – Rider_X
    Commented Jun 25, 2017 at 17:41
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    In short -"money" QRs work perfectly, and there is substantial investment in tooling. Those machines aren't obsolete just because a different system is now available. QRs will hang around on lower price bikes for at least the next couple decades, and on BSOs for double that.
    – Criggie ♦
    Commented Jun 25, 2017 at 20:37

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Are there any reasons not to build road bikes with through axels, even if they are not disc brake equipped? Is this a trend we might see as manufactures produce more pairs of very similar road disc/non-disc models?

It makes very little sense to produce a rim brake bike with thu-axels. What wheel set would it run? Custom? Almost all thu-axel wheel sets on the market now come with disc specific rims that cannot be used with rim brakes.

I would ask what is the advantage to non-racers of having a rim brake frame with thru-axels over a disc frame with thru-axels?

  • Brake modulation? A good hydraulic disc brake has much better modulation than rim brakes.
  • All weather braking - this one is no contest, disc brakes.
  • Wheel compatibility? - you will need to stick with QR then as this is the most common road wheel interface.
  • Familiarity? - If they want to keep with a brake format they are already familiar with I doubt that they would suddenly want to switch wheel interfaces and have any extra wheels they already have rendered useless.
  • Weight - QR interface wins again.

The only "advantage" to the rim + thru-axel seems to be steering response (although some would argue that this is a myth), with the main disadvantages of brake performance and basically no compatible wheel sets.

If the industry produced such a bike, even more people would be lining up complaining that they are producing a completely unnecessary bike configuration.

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Marketing and marketing. 12mm is an up-sell, they make more total profit on the disk brake bikes to they avoid certain improvements on the non-disk bike to push customers toward the disk version. Some customers don't like new stuff, they want the common standard that is proven and has cheap new and used parts available in every store from here to timbuktu. The slight weight or cost difference probably looks like a mountain to some folks(on both sides of the counter) Alternately(or in addition?)this may be a symptom of poor management. Bike companies are not operated by the most elite in business and engineering, and like most companies the marketing department is often allowed to ride bareback over the whole show. One hand doesn't always communicate with the other. Short sighted decisions are often made that save 0.5% this year while costing 5.0% more next year. Many would like to eliminate sizing all together for production and stocking economics.(just look at all the distorted frame geometries to force one wheel diameter for every rider from XXS to XXL, and all with one crank length too)

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