I have seen a Cube Stereo Pro 2022 which looks like it will suit as my son’s next bike. Reading online the original geometry was a 130mm fork however the one I’m looking at has Fox 36s fitted at 150mm travel.
It’s a small frame, but how much will this be a massively negative impact to the bike - when it comes to geometry I’m horrendous for knowing what works and what doesn’t. For my son it would be perfect component wise however if it’s something that’s going to affect the integrity of the frame I will look elsewhere.
This is the link to the original bike - if any geometry wizards are able to give advice on if this is a good/bad move, really appreciated.
I think your looking at around a degree slacker on the seatube and the same on the headtube for +20mm. It probably won't make a huge difference and I think you can fit offset shock bushings to mitigate the slacker seatube to some degree if desired.
I read somewhere that it can weaken the head tube - is this something to concern over or is 20mm difference minor?
It doesn’t weaken it per se, but the leverage on the head tube has increased.
as it’s for a presumably fairly light child, that wouldn’t bother me much
I don't know the bike, but 'long-forking' by an additional 20mm wouldn't unduly bother me, unless the frame is designed eg for 110-130 forks, and therefore the 130 fork currently fitted is at the maximum of the range.
I've run 150mm forks in 3 bikes designed for 130/140 (2 bikes) and 120-140 (1 bike).
You could always run a little bit more sag so the fork sits a little lower in its travel, which would reduce the effective fork length a little.
You can buy an air shaft to drop a 36 to 140mm. at which point I wouldn't be worried at all.
Great thanks all
I'm running a 150mm for on a 130mm hardtail, feels great. I put a -2 headset in which drops the front end a bit and run slightly more sag, and it rips.
FWIW I've been doing similar since running a Mozo Pro 4.5 on an Azonic DS2 in the 90s, I've snapped bikes in loads of other places, but never ripped a head tube off 🙂
An extra 20-30mm is usually fine with most bikes. I’m pretty sure nearly all my (non DH) bikes have been over-forked at some point.