I’ve currently got 120mm Fox F-series QR forks on my ‘main use’ bike (Trek EX with OS headtube) and am wondering whether upgrading the lowers to 15mm bolt thru’s at its next service. FWIW, I occasionally use another bike which has 20mm bolt thru RS forks, and the difference in steering accuracy is quite noticeable. (Unfortunately, I can’t afford to upgrade to some new 20mm axled RS forks)

I only want to bother if I’m going to get a noticeable difference in stiffness & steering accuracy. Has anyone on here ridden QR and 15mm axle forks back to back? If so, do you reckon there’s a big difference?

done exactly what you are proposing to do with a set of talas forks… noticeable difference, esp in the rocky descents / technical stuff, but I got the lowers second hand. cost me about £70 to do with oil and a few other gubbins..

New they are mega money (£120 without seals IIRC) therefore probably not worth it…

if I were you, as you have got a 1.5 headtube I would look at getting a tapered qr15 fork second hand… flog what you have got, would probably work out better in the long run.

Thanks for the feedback, it’s an improvement in rocky/techy performance that I’m after, so good to hear it improves things.

Yeah, the new price is pretty eye-watering, so I’d wondered about keeping my eyes open for any new fork offers.

Nice one getting 2nd hand lowers BTW!

Also done this with fox 140 vanillas , Loco supplied me with 15mm lowers to replace my qr ones, straight swap no messing. Sold the qr lowers too.