Bolt through axles -why ?

[Flick of the Elbow]

I recently became aware that almost all new mtb's now have bolt through axles, and I see that disc brake cross bikes and even road bikes are starting to follow suit. My question is why, what was wrong with the old approach ? I've been using old style qr with disc brakes on my mtb for 10 years, on my commuting/training bike for 3 years and my tandem for 2 years, I've had absolutely no problems with them.

 

[smokeysmoo]

Bolt through axles = strength.

Disc brakes = greater stopping power and removes rim wear issues, however, in the case of road bikes they are fugly IMO.

If your a heavy commuter then discs make economic sense, I'm not and I have no issues with the wear rate of my rims for the mileage I do TBH.

 

[Mr Haematocrit]

Stiffness and tracking are definitely superior on a through-axle fork. Also, you never have to worry if you tightened the skewer tight enough.

 

[Tim Hall]

Stiffness and tracking are definitely superior on a through-axle fork. Also, you never have to worry if you tightened the skewer tight enough.

I'd say the skewer tightness is the more important factor. With the disc calliper on the rear of the fork leg, the braking action tends to rotate the wheel out of the dropout. Google Russ Pinder and James Annan (the wiki article on James Annan has neat summary) for more on this.

(I vaguely remember reading that a hollow axle will be stronger than a solid one because of SCIENCE)

 

[Pale Rider]

Don't most hub gear bikes have a bolt rear axle?

Mine does.

Not sure why.

 

[Crackle]

If you mean mtn bikes, bolt through is a bit misleading as it implies a solid axle. A mtn bike thru axle is hollow and doesn't bolt, it screws into the fork or frame with the advantage of stiffness mainly. They are pretty easy to use, no tools reqd. Bolted axles have different purposes on other bikes.

 

[srw]

"Old style QR"! I remember when I got my first bike with QR skewers - and it wasn't all that long ago. They were strictly exotica for unusual people riding fancy racing bikes.

 

[Flick of the Elbow]

As suggested I just googled Messrs Pinder and Allan. One appears to have failed to tighten the qr correctly, the other appears to have reached a theoretical conclusion. The CTC's Chris Juden was also peddling this line when disc brakes first came out but he seems to have gone quiet on the idea now, possibly because none of his prophecies on the subject are being borne out in practice.
Curious about the tracking point, with mtb forks now so long and with so much travel, can you really tell the difference depending on how the wheel is secured ?

 

[GrumpyGregry]

As suggested I just googled Messrs Pinder and Allan. One appears to have failed to tighten the qr correctly, the other appears to have reached a theoretical conclusion. The CTC's Chris Juden was also peddling this line when disc brakes first came out but he seems to have gone quiet on the idea now, possibly because none of his prophecies on the subject are being borne out in practice.

Millions of mtb-ers ride millions of miles every year with disc brakes secured by QR's. If the QR is done up securely it will not come undone and if it bothers, then zip tie or wire the damn thing shut.

Curious about the tracking point, with mtb forks now so long and with so much travel, can you really tell the difference depending on how the wheel is secured ?

difficult to do back to back tests on otherwise identical bikes but I would say yes you can tell the difference between QR and thru-axle. That admitted I find it very hard to say whether or not the difference makes any difference in normal day to day riding.

 

[marzjennings]

The bolt through axle started with the downhillers who didn't like their wheels flexing when leaned over during turns. When you're already leaned over at the edge of tyre traction, that small out of flex could lead to a tyre sliding out. Also the tyre could rub against the inside of the forks, slowing the rider down. So they slapped in 20mm axles to reduce flex around the hubs. My first DH bike had marks on the inside of the forks where the tyres used to rub, on my second this never happened unless I buckled the wheel.

Yes, you can certainly tell the difference.

FYI Pinder and Allan were scare mongering idiots.

 

[shouldbeinbed]

Don't most hub gear bikes have a bolt rear axle?

Mine does.

Not sure why.

I'd made the off the cuff assumption that the gubbins in the hub may have impeded the through and through nature of a QR spindle but that's very likely me not thinking it through at all & has got nothing to do with it.

I also wonder if e.g. my Alfine 8 is a bit of a heavy lump for a relatively thin QR spindle to manage on the crappily maintained roads with14 stone of me & an often a laden rear end of the bike pressing down on it.

 

[GrumpyGregry]

I'd made the off the cuff assumption that the gubbins in the hub may have impeded the through and through nature of a QR spindle but that's very likely me not thinking it through at all & has got nothing to do with it.

I also wonder if e.g. my Alfine 8 is a bit of a heavy lump for a relatively thin QR spindle to manage on the crappily maintained roads with14 stone of me & an often a laden rear end of the bike pressing down on it.

I weigh more than you, yet we both ride using the same QR's used by racing snakes half our weight. Same size brake pads too. Same gearing. none of which makes a great deal of sense.

 

[Flick of the Elbow]

I find it very hard to believe that the amount of flex in a traditional qr, which must surely be minimal, would result in the tyre rubbing the forks. If this is such a problem how come it doesn't happen on the road ?

 

[Tim Hall]

The bolt through axle started with the downhillers who didn't like their wheels flexing when leaned over during turns. When you're already leaned over at the edge of tyre traction, that small out of flex could lead to a tyre sliding out. Also the tyre could rub against the inside of the forks, slowing the rider down. So they slapped in 20mm axles to reduce flex around the hubs. My first DH bike had marks on the inside of the forks where the tyres used to rub, on my second this never happened unless I buckled the wheel.

Yes, you can certainly tell the difference.

FYI Pinder and Allan were scare mongering idiots.

That's Pinder the paraplegic and Annan, not Allan.

 

[Tim Hall]

As suggested I just googled Messrs Pinder and Allan. One appears to have failed to tighten the qr correctly, the other appears to have reached a theoretical conclusion. The CTC's Chris Juden was also peddling this line when disc brakes first came out but he seems to have gone quiet on the idea now, possibly because none of his prophecies on the subject are being borne out in practice.
Curious about the tracking point, with mtb forks now so long and with so much travel, can you really tell the difference depending on how the wheel is secured ?

I'll ask Chris Juden what his thoughts are on it and report back.