Any updates OP?
If the dropper won't go in are you saying the snag is near the top of the seat tube?
If so, you should be able to see whatever it is. Try ramming an old seat post down there to clear the snag.
LED Endoscope Borescope Inspection Camera 1.5M IP67 LED Lens For Android and PC https://amzn.eu/d/fcmKbfe
just this thread made my buy a small frame to build up a "spare" bike for the OH and try and convert her
I need closure on this, where is OP?
He's miniaturised himself and is inside the frame smoothing off the troublesome sharp edge.
Sorry guys. My trick of a make shift flexi file with emery cloth worked a treat. Quite a few bits came out. The point about the softness of aluminium was valid. That probably wouldn't have worked so easily with steel let alone Ti. It also left a right mess of paper etc but that all came out with gravity.
The build can be completed, will post pics.
Sonder have been very helpful and sympathetic. Had a good chat with the CS manager and they are still "learning about eBay".
There isn't such a thing as "sold as seen" when a brand sells new products direct as a business to consumers. Product liability, warranty and consumer rights remain intact in that case irrespective of price and distribution channel. That was my assumption and that got confirmed by a friend in compliance at an FMCG.
I can see why there would be more friction and less goodwill and perhaps more difficulty to enforce but in this instance Sonder were quite helpful anyway.
Super well done OP. Now you have a super bike for peanuts and can finish and enjoy it
Thanks SA. Yes total build should be around £1,200 as I still have a few bits from the CRC firesale. Aiming for 30lbs or so without pedals although perhaps a tad optimistic.
I assume say, 25% sag out of 120mm will lower the BB by 30mm compared to unsagged? Is it that simple? I also assume BB drop measurements are taken unsagged in the spec sheet?
Does that sag extend the reach at all ? If so by how much?
Thanks all.
I'll be building mine out of junk, i worked out i've got enough unpopular parts sat around that people don't want to buy, that it'll make an excellent bike for the OH/ the boy if he ever wants to ride a light bike
i've got a coil pike, that i'm not sure may be too firm.... superstar wheelset, old xt 11 speed drivetrain, oneup dropper which may be too long.. Sods law says it will come up lighter than my Top Fuel which has some fancy parts on it
re BB sag and reach, technically reach will shorten as the bike moves through its rear travel (i think)
Nicely done, @nickfrog.
Looking forward to seeing the completed build now.
Sonder have been very helpful and sympathetic
Matches my experience.
Enjoy your new bike OP. Interested to hear how it rides.
re BB sag and reach, technically reach will shorten as the bike moves through its rear travel (i think)
Well, if it was only the rear of the bike compressing: yes, the reach shortens as the rear moves though its travel... but the front suspensions is also moving through its travel, and reach lengthens as a fork compresses. So in general, on a full-suspension bike, reach shouldn't fluctuate nearly as much through travel as it does on a hardtail.
Enjoy your new bike OP. Interested to hear how it rides.
Thanks Nick. I will report back although I live on the South Downs and it's a right quagmire so not gonna happen for a while!
I don't think I am very lucky. The snagging is still present.
To minimise the risk of snagging, I ordered a 170mm dropper. While I was at it, I ordered a 31.6 as my longer one was 30.9 with a shim.
It doesn't go in. This happens (used a 31.6mm fixed post for illustration).
No amount of filing makes any difference.
No idea if related to the initial issue but I don't think so. It was just hidden by the smaller diameter. Video:
https://jmp.sh/s/jQ81Jag0LFPCfKl5K6BV
For those who got their frame recently, what did the box look like? Is it a "proper" Sonder branded box? Mine wasn't so trying to establish if it was a return or a "second" with a known issue, being the last one.
Weld blow-through at the seat tube/top tube joint maybe?
No the issue is lower than that at 18.5cm from the top of the seat collar. I *might* be able to see a dark spot in the seat tube now. Not sure at all, but it is very small yet much darker than the surrounding silver aluminium. It looks a bit like if a bit of liquid metal was splashed there and cooled down in situ, if that makes any sense. Will try and do more filing in the morning lol.
When I’m trying to save old steel frames which have stuck seat posts, once they’re out I usually get some dowel wood, cut across the top, slide in some sanding sheets or wet and dry and push it down the seat tube and spin it, clears it in no time
[url= https://i.ibb.co/602wWfYf/IMG-20250202-112544.jp g" target="_blank">https://i.ibb.co/602wWfYf/IMG-20250202-112544.jp g"/> [/img][/url]
What do you guys see?
I'll take the frame to the shop tomorrow for a 4th opinion.
Looks like quite a prominent lip. Can you see and feel it catching with a long thin tool of some sort?
My Large discount Cortex is probably going to struggle with my 170mm dropper. I get 22cm post below the top of the seat tube before it won't go any further. It looks like it's slightly above where the bend in the seat tube start but I assume it's related to that - externally about the point of the Union Jack decal.
How much seatpost can you get into your seat tube?
I'm taking the view that it's an XC frame that was designed when 170/200mm droppers were not common place - it's a pretty flat top tube compared to more modern designs. If it's too tall then a shorter dropper still makes it a bargain bike.
Mine came in a Sonder box that's marked up "2 x Colibri" so obviously not the original Cortex box.
You can still play with the old Cortex bike builder on the Alpkit website, it lists a 170mm dropper as an optional upgrade.
At 5'10", I'm at the small end of a Large frame so not surprising that a 170mm dropper is too big.
Would a 30.9 dropper with a shim work? The thinking being that the shim won't reach as far down as the protrusion inside the seattube, but the narrower dropper might clear it and successfully be inserted deeper into the seattube?
Finished. I managed to transfer everything across from the old frame minus a headset and an inner cable which is a record, I think.
OP, here. Sorry late update. I finally got round to finish this build. Sonder were very good in the end and found an excellent solution, which I probably can't make public 😂.
Anyway, surprisingly light at 28.5lbs (w/o pedals).
Select+ shock
Select+ Pike 140
Roval Controls
SLX + GX cassette
One Up V2.1 180mm
TRP Slate4 brakes
Wolfpack Cross 2.40 tyres
TAG carbon bars and e*13 stem
[img] 
[/img][/url]
Bike proving to be good to ride if a little "passive". But after a few weeks the constant creaks have become unbearable and unfixable. I suspect they come from having to use the wrong size dropper near the bend as it doesn't allow a very long shim.
So the only solution to that particular creak is a 125mm dropper, which is not gonna happen.
Cable noises and rattles are also difficult to reduce any further.
The frame has cost me around £70 in the end but even if it was free, it's not fit for purpose for me, a creak with every crank revolution is funny for a few miles and then not so much.
Will sell it and use the proceeds to go toward a proper product.
Sonder know exactly what's wrong with those frames, hence their excellent customer service in paying me off. Is it a way to run a business?
Mate, just sell it and move on. I’ve never known so much drama over a bike frame before, life’s too short.
I would thread the cable from below, working upwards. Smother the outer in thick grease to overcome any burr it's catching on. Thread the outer in just to the point it will eventually sit at (i.e. 30cm or so within the frame). Push a cable through from the handlebar end and attach to the new cable with tape, then pull back through. I had similar on my Specialized build, it was chewing the outer cable on an internal burr. When you push the dropper into the frame you will need to pull the cable down at the exit point on the seat tube at the same time i.e. push down on the dropper with one hand and pull the cable down and through the exit port with the other.
"I’ve never known so much drama over a bike frame before,"
No drama here, you've made that up.
Can I suggest you ignore this thread if you can't cope with it?
I have no issues with anyone being happy with a frame that rattles and creaks. Conversely, I can't so yes I will be selling it.
76 post thread about a cheap frame that makes a bit of noise and I’ve never had a full price bike that isn’t a little rattly.
Can't help if there's creaks in the linkage, but when I built up my Cortex, I put the cables/hose through a Camelbak neoprene insulated hose cover thing that I had lying around. It's pretty much silent. I don't have any creaks from the linkages either, but mine is the earlier design with the pivot on the seat tube, not the top tube.
I also have a lip in the frame which means I can't push a seat post down as far as you might think - but I'm not the tallest so a 150mm dropper isn't an issue for me - a 150mm oneup would fit, but a brand-x wouldn't. The only creak that I do have is where the seat clamp on the oneup dropper is worn, which makes the seat creak when pedalling sat down...
"76 post thread about a cheap frame that makes a bit of noise and I’ve never had a full price bike that isn’t a little rattly. "
Are you OK? You know you don't have to open the thread if you can't cope with its content.
I never had a full price bike as I only build my own bikes so I can't really comment. I certainly never had to cope with a permanent loud creak in the seat tube (in addition to the rattles, that are not little). Sorry to hear about your issues on that front.
