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Mac_89

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Discussion starter · #1 ·
I'm 100kg down from 120kg at my heaviest. I have a OneUp V2 210mm post in a MY2020 Santa Cruz Megatower frame. This is post #2 and the first one went the same way.

Image


The anodising has worn away around the very bottom part of the post, right at the front, and now the alloy itself is wearing down. It creaks badly. I can silence the creak with grease but it comes back after 2-3 rides and I have to pull the dropper, clean and apply fresh grease - it’s a pain.

Here’s a pic showing the inside of the seat tube. It's a screengrab from a video because it was hard to get good pics but I can try to get some high resolution pics if needed. I can’t see any obvious damage but would appreciate any tips on what to look for, just for peace of mind. The edges you can see are just strips of carbon which I assume are to reinforce the frame. I've marked roughly where the post finishes in the second pic. I think it's rubbing against the edge of that strip.

Image

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I need to buy another dropper post because I’m fed up with pulling it every few rides, but if I go with the same post again I’ll only end up back here in a year or so.

Here’s what I’m thinking:

1. Go with a shorter drop to raise the bottom of the post away from any rough edges and reduce flex (OneUp allows you to shim the travel down by 20mm so I can try that for now)
2. Go with a different manufacturer for the dropper - BikeYoke or Wolftooth perhaps. Maybe it won’t flex as much. Obvious problem with this is spending twice as much for no guarantee it changes anything.
3. Contact Santa Cruz? Maybe it’s considered a defect. Maybe there is a max insertion depth for the frame and this exceeds it. Maybe I was/am too heavy for this setup and this is just a consequence of that.

Would really appreciate any input.
 
#2 ·
Mac_89 said:
I'm 100kg down from 120kg at my heaviest. I have a OneUp V2 210mm post in a MY2020 Santa Cruz Megatower frame. This is post #2 and the first one went the same way.

View attachment 2106339

The anodising has worn away around the very bottom part of the post, right at the front, and now the alloy itself is wearing down. It creaks badly. I can silence the creak with grease but it comes back after 2-3 rides and I have to pull the dropper, clean and apply fresh grease - it’s a pain.

Here’s a pic showing the inside of the seat tube. It's a screengrab from a video because it was hard to get good pics but I can try to get some high resolution pics if needed. I can’t see any obvious damage but would appreciate any tips on what to look for, just for peace of mind. The edges you can see are just strips of carbon which I assume are to reinforce the frame. I've marked roughly where the post finishes in the second pic. I think it's rubbing against the edge of that strip.

View attachment 2106340
View attachment 2106341

I need to buy another dropper post because I’m fed up with pulling it every few rides, but if I go with the same post again I’ll only end up back here in a year or so.

Here’s what I’m thinking:

1. Go with a shorter drop to raise the bottom of the post away from any rough edges and reduce flex (OneUp allows you to shim the travel down by 20mm so I can try that for now)
2. Go with a different manufacturer for the dropper - BikeYoke or Wolftooth perhaps. Maybe it won’t flex as much. Obvious problem with this is spending twice as much for no guarantee it changes anything.
3. Contact Santa Cruz? Maybe it’s considered a defect. Maybe there is a max insertion depth for the frame and this exceeds it. Maybe I was/am too heavy for this setup and this is just a consequence of that.

Would really appreciate any input.
Click to expand...
Yes, I have read of this similar trouble. The solution was a shorter insertion. But then there is even less leverage to resist pressure at the clamp and a crack is on its way.

The frame is too lightly built for you. Except, what is the exact post diameter? You want it to measure 27.15, for example, in a 27.2 tube. As close as you can get. The tube is hard to measure and carbon will be all over the place in tolerance.

There are no grit scratches I can see. Are you using SAC-2? I have found the grit makes up for poor tolerance. So much that it takes force to get the post in. That makes for 15 pounds or whatever of slip resistance in addition to the clamp.

But to be chewed like that, wow that's weird.
 
#4 ·
I have the same issue with a 185mm Bikeyoke post in a medium V1 Megatower and I am quite a bit lighter. The seat tube is slightly wider below the top tube joint and as the frame flexes, its rubs against the post and creaks like hell. It took me forever to figure out what was going on. I solved it by carefully placing a piece of tape inside the seat tube, in the spot where its rubs the post, and it has been quiet since.
 
#7 ·
I'd look for a dropper that is the same diameter for it's entire length and then as much insertion as possible.

OneUp's use a thinner diameter stanchion that's prone to flex and binding. That's why OneUp specifically recommends only 4 nm of torque on the seat clamp, as more can effect the dropper's performance.
 
Discussion starter · #10 ·
maxtorque said:
Yes, I have read of this similar trouble. The solution was a shorter insertion. But then there is even less leverage to resist pressure at the clamp and a crack is on its way.

The frame is too lightly built for you. Except, what is the exact post diameter? You want it to measure 27.15, for example, in a 27.2 tube. As close as you can get. The tube is hard to measure and carbon will be all over the place in tolerance.

There are no grit scratches I can see. Are you using SAC-2? I have found the grit makes up for poor tolerance. So much that it takes force to get the post in. That makes for 15 pounds or whatever of slip resistance in addition to the clamp.

But to be chewed like that, wow that's weird.
Click to expand...
I hear you on the clamp thing with a shorter post.

The seat tube is 31.6mm (according to Santa Cruz) with a 36.4mm clamp. I don’t think my calipers are accurate enough to measure the post properly and I’m sure you’re right about the carbon tolerances.

At the moment I use a dowel to reach into the frame and put some grease around the lower part of the tube (to quiet the creak down). I only use carbon paste around the top of the post and between the frame and seat clamp. I’ll try using it instead of grease and see if it’s any better.

SpinningLizard said:
What is the max insertion length from Santa Cruz for that frame, if you are exceeding that then it is on you. If you are not, frame should be warrantied.
Click to expand...
I’ve e-mailed them to find out. I’ll post up their response in here just in case anyone stumbles across the thread looking for it (y)

LowEntropy said:
I have the same issue with a 185mm Bikeyoke post in a medium V1 Megatower and I am quite a bit lighter. The seat tube is slightly wider below the top tube joint and as the frame flexes, its rubs against the post and creaks like hell. It took me forever to figure out what was going on. I solved it by carefully placing a piece of tape inside the seat tube, in the spot where its rubs the post, and it has been quiet since.
Click to expand...
Yes I’ve noticed it flares out under the top tube join and it’s not round either. The frame flexing there is something I hadn’t considered. I’ll definitely give the tape a go, thanks.

jeremy3220 said:
I had this issue on my Tallboy V4. Swapping from a 210mm Oneup to a 240mm did the trick. Going with less insertion depth seems like a move in the wrong direction.
Click to expand...
Ah that’s good to know - I’m not alone then. I run this one with 30mm of post showing above the clamp, so a 240 would be the perfect amount of drop with the collar flush, but I’m not sure it’ll fit. It’s an XL frame. I may be able to get one in if I shim the travel down to 220 though. Waiting to hear back from SC on max insertion and will go from there.

mikebikebend said:
4: No grease, carbon paste instead.

Congrats on the >3 stone weight loss!
Click to expand...
Thank you! I’m aiming for 90kg. Hopefully I’ll stop breaking bikes once I get there :LOL:
 
#11 ·
My 210 v2 did this as well in my L nomads (5&6). The solution is laying in a thick layer of carbon paste and a key trick is apply the paste to the inside of the seat tube as well. If you just put it on the post then most gets wiped off as you insert. You need to apply to the tube so it gets pushed down and fills any small gaps as you insert.

Also the V2 210 has a really long section that is a smaller diameter vs the 180 and others, I have no idea why oneup did this in the V2 but the V3 is no longer like this so more post is in contact with the frame and seems to have improved this a ton on my L nomad 6 and Bullit. Also you get the benefit of it being way smoother and doesn’t need a booty bump to get it to drop.
 
#12 ·
Jesse Hill said:
My 210 v2 did this as well in my L nomads (5&6). The solution is laying in a thick layer of carbon paste and a key trick is apply the paste to the inside of the seat tube as well. If you just put it on the post then most gets wiped off as you insert. You need to apply to the tube so it gets pushed down and fills any small gaps as you insert.

Also the V2 210 has a really long section that is a smaller diameter vs the 180 and others, I have no idea why oneup did this in the V2 but the V3 is no longer like this so more post is in contact with the frame and seems to have improved this a ton on my L nomad 6 and Bullit. Also you get the benefit of it being way smoother and doesn’t need a booty bump to get it to drop.
Click to expand...
Like with tapered thru axle, why? A gram saved but weaker.

I've been using a dowel with three beads of SAC-2 as long as the seatpost will be in seat tube. Then I play "doctor", try not to touch the walls till in all the way, then smear it around. I need that full grip all the way down. It's properly stated that the clamp is where it's at for holding the post up. But with a full coat it takes substantial force to get a well fitting post in. That friction/interference fit is then also contributing to keeping the post from sinking. So much that I don't have to over tighten the clamp like I used to.
 
Discussion starter · #14 ·
Santa Cruz have said the maximum seatpost insertion length on an XL V1 Megatower is 245mm.

I've been running mine at around 250mm, so slightly over.

For now I'm going to dismantle the post, rotate the outer tube 180 degrees (so the non-worn side is facing forwards), shim the travel down 10mm and pull it out by 10mm to leave 240mm of post inserted. If it's wearing down again after a handful of rides then it might be time for a new frame.
 
#15 ·
Mac_89 said:
Santa Cruz have said the maximum seatpost insertion length on an XL V1 Megatower is 245mm.

I've been running mine at around 250mm, so slightly over.

For now I'm going to dismantle the post, rotate the outer tube 180 degrees (so the non-worn side is facing forwards), shim the travel down 10mm and pull it out by 10mm to leave 240mm of post inserted. If it's wearing down again after a handful of rides then it might be time for a new frame.
Click to expand...
Honestly I don’t think it’s your frame and more the v2 post. My v2 was pretty finicky too. Also if you’re careful you can get more post in than what SC says. They just have to give extra room for cable bind etc but I’ve managed to fit my v3 210 in my large bullit past what SC says is max but it is right on the edge and you have to get the housing just right or it’ll bind.
 
#16 ·
LowEntropy said:
I have the same issue with a 185mm Bikeyoke post in a medium V1 Megatower and I am quite a bit lighter. The seat tube is slightly wider below the top tube joint and as the frame flexes, its rubs against the post and creaks like hell. It took me forever to figure out what was going on. I solved it by carefully placing a piece of tape inside the seat tube, in the spot where its rubs the post, and it has been quiet since.
Click to expand...
what kind of tape and how did yu get the tape down there? thanks!
 
#18 ·
I have a oneup v3, 210, shimmed down to 190 in a Santa cruz Hightower v3 large. I get a subtle knock sound when seated and shifting weight around on the seat. The sound is a lot like a cable hitting the frame lightly, but it's not that. I've isolated it to the dropper and found this thread. At first I thought it was the main internal shim of the dropper as the pins wear it down fast, but I think it's actually caused by some action between the dropper and the frame like this thread suggests. I have sever faint wear spots on my dropper's black coating. The knock goes away after adding some carbon paste, but it always comes back within a ride or two and gets worse if I don't add more paste.
 
#19 · (Edited)
I know this is an older thread but the topic is the only place I've found this issue being discussed and I fixed the issue...
I did two things. As recommended above I used some hockey tape and placed a strip inside my seat tube where the post wear is. For me, that spot is the lower intersection where the top tube and seat tube meet. The second thing I did was an old school shim trick. I cut a piece of soda can to about half the size of a business card with round corners to not dig into anything and used a drop of super glue to adhere it to the dropper post where the worst rub spot it is. The very small amount of glue is just enough to hold the piece of aluminum in place while I slide the dropper down into the seat tube.

After nearly 90 miles of hard MTB riding not a sound. Before, I couldn't go more than 15-25 miles and the sounds would come back even after using lots of carbon paste. The carbon paste works but quickly dilutes or something and the sounds come back with weight shifting/flex around mile 15-25.

I think the main issue is the design of certain dropper posts like OneUp or Bike Yoke that have the beveled thinner section low on the main tube (lower tube) of the dropper. (the section where the dropper tube gets thinner right above the actuators.) I think droppers that are solid all the way through the length of the tube would be better (like the new Fox). It's that thinner beveled edge that is flicking against sections of carbon that are protruding a bit within the frame. We need a full tight fit for the entire length.
 
#20 ·
Suns_PSD said:
I'd look for a dropper that is the same diameter for it's entire length and then as much insertion as possible.

OneUp's use a thinner diameter stanchion that's prone to flex and binding. That's why OneUp specifically recommends only 4 nm of torque on the seat clamp, as more can effect the dropper's performance.
Click to expand...
I think you nailed it with the "same diameter for it's entire length." That would explain why both oneup and bike yoke have the issue, and when I covered part of that thinner section with a strip of aluminum can the noise is gone.
 
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Mac_89
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