[ocnLogan]

I've read a number of times that a limitation for longer travel dropper posts, is the seat post diameter itself. Something about the size of the bushings, overlap, something (I remember reading an article about it sometime, but can't find it offhand). I hear thats one of the reasons for the 34.9mm seat post diameter becoming a "thing".

I'm going to buying a new frame sometime here in the next couple of months. I'm noticing a few of the frames I'm considering have 34.9mm seat posts. But I'm curious if I'm buying new for the build if I "should" be going with a 34.9mm post for those frames, or if it would be a smarter move to grab a 31.6mm and shim it down, giving me something that I could swap around more in the future?

The one thing I can say after looking at the specs of the PNW Rainer 3, and Oneup V2, is that the 34.9mm diameter posts are heavier than the smaller diameters.

Here are the OneUp specs:

(31.6) 120mm 450g / 150mm 500g / 180mm 545g / 210mm 590g
(34.9) 120mm 545g / 150mm 605g / 180mm 660g / 210mm 710g

Here are the PNW specs:

(31.6) 125mm 474g / 150mm 524g / 170mm 554g / 200mm 598g
(34.9) 125mm 576g / 150mm 638g / 170mm 674g / 200mm 734g

Does anyone know if larger 34.9mm diameter dropper posts are actually more reliable than the their smaller diameter counterparts? Are they using all that extra diameter "correctly", and have less play or something? Just curious if anyone has any experience one way or the other.

I'm no weight weenie (my bike is ~37lbs right now), but if there isn't a difference in reliability or something between the two sizes, going with the smaller 31.6mm post, and saving some weight, and gaining some cross compatibility seems like it might be the better option? But if they are much better in some way, then I might be worth it.

Thoughts?

 

[834905]

I’ve got thousands of miles on a 30.9 PNW Bachelor and it’s operated flawlessly. I’ve taken it apart and greased it twice and that’s it.

 

[wschruba]

Two thoughts:

1) every time you add an extra part, it's a place for extra movement to potentially occur (creaks).

2) unless there is a commensurate increase of stanchion diameter (usually not the case, as it would cause more parts to need to be manufactured), there is no chance to increase stiffness.

AFAIK, only one manufacturer makes any mention of increased stanchion size, though I don't recall which.

 

[Isildur]

From what i've seen and read, a larger diameter dropper will increase reliability due to bushing overlap and overall stanchion diameter. But, that's the trick, to actually increase the stanchion on the dropper relative to the tube.

Plenty of brands have skinny 27.2 posts, and the stanchions are different between the 27.2 and 30.9/31.6 sizes. but the only brand that does this when increasing from 31.6 to 34.9 is Bike Yoke AFAIK. Sacki has been pretty vocal on this in the past to say that if he had his way, the only seat tube size to exist would be 34.9

 

[richj8990]

I've read a number of times that a limitation for longer travel dropper posts, is the seat post diameter itself. Something about the size of the bushings, overlap, something (I remember reading an article about it sometime, but can't find it offhand). I hear thats one of the reasons for the 34.9mm seat post diameter becoming a "thing".

I'm going to buying a new frame sometime here in the next couple of months. I'm noticing a few of the frames I'm considering have 34.9mm seat posts. But I'm curious if I'm buying new for the build if I "should" be going with a 34.9mm post for those frames, or if it would be a smarter move to grab a 31.6mm and shim it down, giving me something that I could swap around more in the future?

The one thing I can say after looking at the specs of the PNW Rainer 3, and Oneup V2, is that the 34.9mm diameter posts are heavier than the smaller diameters.

Here are the OneUp specs:

(31.6) 120mm 450g / 150mm 500g / 180mm 545g / 210mm 590g
(34.9) 120mm 545g / 150mm 605g / 180mm 660g / 210mm 710g

Here are the PNW specs:

(31.6) 125mm 474g / 150mm 524g / 170mm 554g / 200mm 598g
(34.9) 125mm 576g / 150mm 638g / 170mm 674g / 200mm 734g

Does anyone know if larger 34.9mm diameter dropper posts are actually more reliable than the their smaller diameter counterparts? Are they using all that extra diameter "correctly", and have less play or something? Just curious if anyone has any experience one way or the other.

I'm no weight weenie (my bike is ~37lbs right now), but if there isn't a difference in reliability or something between the two sizes, going with the smaller 31.6mm post, and saving some weight, and gaining some cross compatibility seems like it might be the better option? But if they are much better in some way, then I might be worth it.

Thoughts?

The PNW weights are INCORRECT, as least the one I got. I have the 31.6 125mm and it's 590g, not 474g. So about 0.2 lbs more than advertised. The two OneUP's that I have, 30.9 120mm is 454g and the 31.6 150mm is around 500g, so 0.1 lbs more for 25mm more. And a bit less grams than advertised.

I'm not saying PNW is a bad dropper, I think overall it's smoother actually. But the weights are wrong, just be warned. Your bike is 37 lbs? WTF? Is it an e-bike? I guess you shouldn't worry about PNW weights being off a bit then lol. I thought about doing the lesser diameter too so I can switch it between bikes, but I decided that if and when it starts sticking and can't go all the way up anymore, instead of servicing it you just plunk down another $200-250 later and get a new one anyway; that amount of cash is peanuts in the MTB world. Sell the old one on E-Bay for $100. You'll have done your good deed for the month, someone else will be happy buying it.

 

[The_Bob]

Whichever diameter you get, go for a BikeYoke. Smoothest action, best return speed, easy to rebuild and with full parts availability. The difference between a budget and a premium product is stark in this case.

 

[Isildur]

Whichever diameter you get, go for a BikeYoke. Smoothest action, best return speed, easy to rebuild and with full parts availability. The difference between a budget and a premium product is stark in this case.

I definitley agree with the above. I've got 3x Bike Yoke (2x Revive, 1x Divine) and they're much smoother than any other posts I've used. Even the new PNW I got for a review isn't as smooth.

 

[Sparticus]

I've got a 185mm BikeYoke and three 210mm OneUps.
The BikeYoke is unquestionably the best post IME.
But not by a lot.
The OneUp isn't a bad post -- in fact it's darn good.
This is why I have three OneUps. They cost something like 40% less than the BikeYoke.
If cost is no object, yeah -- BikeYoke.
Except not the BY lever. OneUp's dropper lever is far more ergo IMO.
I use OneUp levers on all my droppers.
=sParty

 

[Jayem]

I have several PNWs...just rebuilt one of them yesterday. I also have a Bikeyoke Revive. No comparison. The bikeyoke is like butter, all the time. Ok, you can run even a bikeyoke into the ground, but IME, it lasts many times longer than these PNWs. They start working like crap within a few months IME, like 3-4. Bikeyoke action and speed is so easily modulated and so unaffected by everything that seems to plague every other post. I don't think the PNW is crap, for the price it's pretty amazing. If I get another long post though...bikeyoke is probably where I'm going.

 

[ocnLogan]

I appreciate all the input here.

I ended up buying the frame with the 31.6mm seat post diameter, so the whole topic is somewhat moot at this point. Although, I still do find it pretty interesting.

On the topic of droppers thought... I was looking a bit into the BikeYokes. They look great, but expensive. I also noticed the Divine (rather than the Revive V2). Does anyone have any feedback on the cheaper Divine?

Also but saw it mentioned in one review that the BikeYoke posts clamp the cable at the post end, rather than the lever end like everyone else does. Does this really mean anything, other than you must have to use the bikeyoke lever? Or is there something else I'm missing?

 

[Laupe]

I've got a 185mm BikeYoke and three 210mm OneUps.
The BikeYoke is unquestionably the best post IME.
But not by a lot.
The OneUp isn't a bad post -- in fact it's darn good.
This is why I have three OneUps. They cost something like 40% less than the BikeYoke.
If cost is no object, yeah -- BikeYoke.
Except not the BY lever. OneUp's dropper lever is far more ergo IMO.
I use OneUp levers on all my droppers.
=sParty

I am looking for a dropper for my future xc bike, i want around 125mm and a fast return with a clunk so i know when it's fully extended. I also want them to last long so i can swap to new bikes when i change bike and i would like if i can service them myself.

Would you say it's worth bying BikeYoke over OneUp ?

 

[jeremy3220]

Also but saw it mentioned in one review that the BikeYoke posts clamp the cable at the post end, rather than the lever end like everyone else does. Does this really mean anything, other than you must have to use the bikeyoke lever? Or is there something else I'm missing?

Why would that preclude using a lever that clamps the cable?

 

[Sparticus]

I am looking for a dropper for my future xc bike, i want around 125mm and a fast return with a clunk so i know when it's fully extended. I also want them to last long so i can swap to new bikes when i change bike and i would like if i can service them myself.

Would you say it's worth bying BikeYoke over OneUp ?

Yes.
My BikeYoke is 4 years old and has been on multiple frames.
Still works like new.
Worth the price of admission.
=sParty

 

[Sssteveyoung]

Why would that preclude using a lever that clamps the cable?

I realize this thread is a few months old but was playing with this at the weekend so figured I’d note here for anyone searching in future.

The original BikeYoke Triggy has a seat for the cable nipple and also a grub screw that clamps the cable next to the nipple at the lever end.

The Triggy alpha just has a grub screw and clamps the cable at both ends (I.e. no need for the cable nipple at either end).

The Triggy alpha is more expensive, has nice bearings and is more adjustable in terms of positioning.