I am building up a 29er lightweight hardtail, for racing and long distance stuff.
The frame has a tapered steerer, and am looking at 100mm forks next. The question is, what difference will I notice, if any, between 9mm QR, and 15mm bolt through. Thinking of the Mavic SLR wheels, which I think will run either system.
Any real world experience of both systems would be appreciated.
Thanks

for a 29er I think you’d notice the difference, however, Mavic wheels are pretty stiff from my experience especially compared with crests for example. A lot of it is subjective and to some extent based on your riding style/ weight. It’s worth considering the qr forks will be a fair bit lighter but you need to factor in the weight of the qr too! I went with some 20mm rebas and havens as I wanted something dependable and analogous to how my big bike felt. Overkill for xc racing but I only do sport or no fuss style team events so is a good compromise for me.

I noticed quite a difference between QR and 15mm bolt thru going from 100mm QR to 140mm 15QR with a 26er. On a 29er there’s about 60mm greater length from ground to headset bottom cup for a given fork travel, so a 100mm 29er fork will be about as flexy as a 150mm 26er fork built the same way.

My old QR straight steerer Revs were horrible noodly things and swapping them for the 20mm tapered steerer model improved things a lot but I still think the chassis is stretched beyond its capabilities in 26″ 150 mm guise. I can see the legs walking and flexing on obstacles.

The Domains, Recons and Pikes on my other bikes are similar spec and are fundamentally stiffer. Light forks are light for a reason imo.

I wouldn’t run an old skool QR on any fork if I had the choice – 15mm or 20mm for me from now on. Noodlyness is one consideration but so is snapping QR’s and having the bloody things undoing themselves.

Yes there is a definate difference, especially when the terrain gets rocky. Being able to hold a line better and deal with deflections is a considerable advantage.

If your wheels are laterally stiff, then going to QR15 may be more noticeable.

Depends a lot on the forks… Frinstance, it used to be that if you were talking about 15mm, you were mostly likely talking about a Fox 32, and there the difference is pretty big because the 32 chassis is a bit marginal and flexy anyway. Whereas the difference between a Revelation QR and 15mm is much smaller.

It does make sense to go to a bolt-through if you can though, there’s so little disadvantage.