150mm fork on 120 frame

[dom vaccarello]

Can you put a 150mm fork on a 120 frame

[aes5455]

From my tiny bit of understanding you can… BUT the way the frame will be stressed is going to be changed, along with geometry etc.

I thought about 10 maybe 20 mm + or – was as far as you should push a frame.

What material is the frame made of? Have you considered changing tires and air pressure to adjust ride quality?

I’m assuming you’re looking for a smoother ride

[mongwolf]

Such an increase is generally not recommended because the frame was not designed for such an increase and may be stressed and damaged.  I have read that at the most you should increase by 20mm.  Plus, the bike may not ride as well.  So you might go with a 140mm fork for safe measure and follow conventional wisdom.  If you are one who likes to test things and push boundaries and if the frame was no longer of any value to you using a 120mm fork, you could give the 150mm a go and see what happens.  But just be ready for the worst to possibly happen.

[sissypants]

It is possible, nothing will prevent you from doing so. But as alluded to above by others, the character and handling of your bike will be dramatically affected.  Your bike has the geometry of a trail bike, you are trying to turn it into a low-travel enduro bike, but you don’t have enduro geometry.  See Aaron Chamberlain’s recent post on how enduro and trail bikes are differentiated.  Your frame will not deliver an “enduro feel”.

I would not be too concerned about frame damage especially if you are not riding carbon. You will still get stresses in all of the same positions, albeit a little more angular stress in the headtube due to the extended HTA/wheelbase.

Do you really need more than 120mm of suspension?  If you’re riding enduro, sell your bike and get an enduro bike. If you’re not riding enduro, maybe you could achieve a more plush feel by going full-suspension, getting a carbon handlebar (for shock absorbance) or if you’re a real chicken by getting one of those Suntour shock-absorbing seatposts.

[Dr Sweets]

@domvaccarello:”Can you put a 150mm fork on a 120 frame”

OMG! Are you insane?!? You’ll DIE!!! WE’LL ALL DIE!!!

Actually it will not matter that much unless your frame is a department store rig or an ultralight XC bike neither of which have the necessary strength to handle additional forces created by a longer lever arm. I’ve routinely over-forked my  bikes for years. Yes, you might have to slide a little more forward on the saddle during ascents, but the improvement in descending capabilities is worth it, IMHO. My last two bikes actually had matched travel front and rear, but just about every hardtail I’ve owned I ran more than the recommended fork travel. This will be the case on my new (to me) Honzo, because, party.

[jgmtb]

hi dom, you yea can, but that is maybe a bit too much. All things being equal, it will make your bike slacker and raise the bottom bracket. So while you are looking for a bit more travel on the way down, the higher BB does not help with cornering. So it’s a trade-off. Where it is not a trade-off will be climbing- the slacker angles (especially with the fork locked out, as when open the sag somewhat offsets this) and high bb make for a poorer climbing machine. You call, go for it if you feel like it!

[Alvin Mullen]

Listen to the Doctor!!!  “Your frame will break” has the same basis in reality as “You must change your oil every 3000 miles” It may have been true many years ago, but things are built much better than they use to be.

 

Most of the extra force created by the extra length it transmitted up the fork through the suspension, so much of the extra force is absorbed by the extra suspension.

 

Now certainly your handling will change, and you may or may not like what it does to the feel.

[crackerman]

I’d agree with the +20mm for about as much as you want to go up without really changing the geometry. That being said I was using a fatbike speced for  a 100mm fork, with a 150mm fork for about 3 months and it felt pretty good, no complaints.. I’ve since lowered it to 120mm.

[Author]

Posts