QR or Though Axles?

[Espresso_]

Hi all

Just musing on an upcoming mid-fat wheelset build which will be used on a rigid steel 26" MTB frame, with regular QR open dropouts front and rear.

I've seen the 9mm (front) / 10mm (rear) through-axle option from DT Swiss and the like.

What's the experience of others on whether buying through axle hubs? Is it worth it for 9/10mm applications over the regular QR? For me, the cost increase is not trivial, given the added costs of:
- through axles themselves
- front and rear hubs (I have a 9mm QR front hub lying around ready to use)
- conversion kits

(Although at the cheap end, I could get a whole 9/10mm through axle setup for $180-ish including front and rear hubs and axles)

Also, assuming there is a noticeable stiffness increase, is it mainly in the front wheel?

E

[trailgumby]

Not sure if there's a differing standard for fatbikes, but thru axles are generally 15mm or 20mm x100 on the front (although I think RockShox may have capitulated and gone with the 15mm Fox standard) and 142x12mm rear.

Just recently there's a new "Boost" standard where the front is 110mm wide and the rear 148mm, so that we can have the pleasure of seeing all our existing spares and race day wheels become redundant and buy new stuff if we want to upgrade to a new bike and keep the industry in the lifestyle to which it has become accustomed. /rant

To answer your question: Thru-axles do make the bike noticeably stiffer laterally, and steering more accurate and responsive. You don;t notice it at first, until you step back onto a bike without it. At least, that's been my finding with my Scalpel 29er. QR forks and rear frame triangles feel like wet noodles in comparison. Is it just the axles? Perhaps not, but impossible to tell without two identical frames for comparison.

Do you really need it for a fully rigid bike? Probably not, some degree of flex can be a handling help. However a fat bike does have a lot more movement going on with tyres and rims, so maybe it would be improved with thru axles.

For the rear I would counsel against going with the DT Swiss system with the external lever. It's fragile and if it takes a hit off a trail side rock you'll be hoping not to get a puncture before you can get to the bike shop. The allen key Syntace unit is much the better choice. Much lighter, and reliable.

[Espresso_]

Not sure if there's a differing standard for fatbikes, but thru axles are generally 15mm or 20mm x100 on the front (although I think RockShox may have capitulated and gone with the 15mm Fox standard) and 142x12mm rear.

I'm only interested in the 9mm/10mm through axle to fit an open dropout QR frame. I can see that the 15mm and 20mm options would be stiffer than QR, but aren't relevant to my frame/fork. It's just a regular mountain bike frame.

For the rear I would counsel against going with the DT Swiss system with the external lever. It's fragile and if it takes a hit off a trail side rock you'll be hoping not to get a puncture before you can get to the bike shop. The allen key Syntace unit is much the better choice. Much lighter, and reliable.

Why is that only a problem on the rear?

(The Syntace unit looks to be a 142mm fitting? If so, it won't work with my standard 135mm 10mm open dropout).

cheers

E

[Duck!]

What you're looking at is what's sometimes referred to as "bolt-up" hubs. Because they're still reliant on being properly tightened for secure fitting in frame or fork they have no particular advantage over normal quick release axles. Depending on the shaping of the hub end caps and resulting contact area on the dropout face, bolt-ups can even potentially be less secure than Q/R; Q/R at least has decent-sized locknuts on the hub to grip against the dropouts.

[trailgumby]

I'm only interested in the 9mm/10mm through axle to fit an open dropout QR frame. I can see that the 15mm and 20mm options would be stiffer than QR, but aren't relevant to my frame/fork. It's just a regular mountain bike frame.

That's a bolt-up, not a thru-axle. It has nuts at either end. Thru-axles do not have open dropouts, as they rely on the axle threading into a socket at the opposite end to insertion. Have you perhaps got the systems confused?

Your other option might be a QR axle with large diameter knurled end caps. I think it was Specialized came out with such a system, and it would have led to a significant improvement in stiffness but was overtaken by the then new-to-market thru axle systems.

Duck! may be able to provide more detail.

Why is that only a problem on the rear?

Because you can see and avoid rocks with your front wheel using your peripheral vision. The rear is behind, out of sight.... and it tracks on a different line to the front.

Academic for you, as thru-axles are not compatible with your frame as it now stands.

[ianganderton]

Hard tail frames are so stiff anyway there is no benifit to be gained from bolt up options. Stick with QR and spend your money on something that will make a difference.

Were the stiffer axle types make a difference is in systems that have lots of potential for flex like suspension. Suspension forks for instance. It's for good reason the stiffer axle designs all started in fork designs because structural rigidity was a significant problem that needed solving

[ianganderton]

I like this info from Cotic http://www.cotic.co.uk/geek/page/qraxlehardtails

[Espresso_]

That's a bolt-up, not a thru-axle. It has nuts at either end. Thru-axles do not have open dropouts, as they rely on the axle threading into a socket at the opposite end to insertion. Have you perhaps got the systems confused?

I don't have the systems confused, but I might have the terminology confused. You're right on what I need though.

Some manufacturers call this a through axle:


Superstar 9mm Front QR Through Axle

Some manufacturers call this a through-bolt:


DT Swiss RWS THRU BOLT

Both are specifically designed for open-dropout QR fittings.

E

[trailgumby]

OK, got it. Calling them thru-axles is slightly misleading.

The DT Swiss one I'd give the miss. Those plastic levers are prone to breaking if they take an impact - and it doesn't need to be a big hit, either. If you need to remove the wheel for any reason you're then in trouble - it's a bike shop job to get it out. A mate had that issue on his late and unlamented Giant Reign.

Neither are going to add much if any rigidity without a larger diameter axle face engaging the inner facee of the dropouts.

You'd be better off with a skewer with a good quality clamping lever IMO.

[Espresso_]

Thanks all - helpful advice. I think I'm going to give all this a miss and go with standard QR.

E