Got into work a couple of days ago, was chatting to a work colleague when I noticed a major crack in the seat tube of my S-Cross CB. -Please see first two attached images.

 

I contacted Oxygen bicycles to alert them and ask if it was under warranty. The next day the came out and picked the bike up from my work place and back to their workshop.

 

24 hrs later they have replaced the frame.

 

The new frame is of a slightly different design, apparently the seat tube is slightly thicker so that it blends in better with the rest of the bike (the old frame having a slightly thinner tube, according to Oxygen, cannot possibly have had anything to do with the failure -but this begs the question why make such a aesthetically minor amendment for the sake of aesthetics?). The new frame has fractionally shorter seat stays, so my Schwable big apple tyres now no longer fit, they just catch the fixing for the mudguard nearest the bottom bracket. -No problem 2x Marathon Plus Tours are on order. Oxygen did offer to fit a pair of stock tyres FOC, but the roads of Sheffield seem lined with glass shards at the moment so I declined. I trust the marathons more.

 

Oxygen seem to think it is related to my use of the Suntour NCX seatpost, they kindly provided an alternative suspension seat post. The NCX seat post had been well inserted into the old frame (photos also attached) and was set appropriately for my height. One of the reasons I bought the NCX seat post was because the stock seat post would just not lock in place, I would sit on it and the saddle would move, poking me in a very sensitive place.

 

I cannot knock them for service, but they did make me feel like a naughty school kid, why had I changed the tyres, why was I using a suspension seat post... At one point they commented that I had ridden the bike many miles. Of course I have, it is sold as a commuter and I ride ~100 miles a week. I would not have bought it if it wasn't meant for this purpose -to which they agreed.

 

Oxygen's reputation is good, I watch someone ride one of their older style bikes to work everyday (has a battery behind the seat tube), I've no doubt they can be reliable. However, I'm still left with the feeling that I'll be glad when my warranty expires so that I don't need to justify every minor change I make to the bike. I do feel I've had a run of bad luck with the bike with spokes popping, loose battery, bad punctures early on, and cracked frame.

 

I should be grateful, fast turn around, and the issue was sorted promptly. But I'm not!

Grump over!

Edited May 26, 20178 yr by DBye

24 hrs later they have replaced the frame.

blimey, that's a cracking customer service.

don't knock it, I don't think many bike companies can react that quickly.

It seems to me that your SP12 seat post is 350mm long.

If you are 6ft or over, you should use a 400mm post.

I'm 5ft 11", I've taken out the seat post they've supplied and photographed it next to the NCX and ruler for scale.

 

The one they have supplied is shorter than the NCX.

 

I agree it is excellent service. I just wish they didn't make me feel like I was bothering them!

 

Just for clarity, my work place if ~5 miles from Oxygen.

It looks to me that the NCX seat pin does not go far enough into the frame. It looks like there's an impression of the frame weld at the bottom, which shows that the bottom of the pin just reaches the bottom of the weld. I had one like that, and this the result. Note the position of the seat-pin.

 

http://i451.photobucket.com/albums/qq236/d8veh/Brokenpost2.jpg

 

Edit: After looking at your last photo, it does look like the NCX seat-pin is long enough. I wonder ifit has anything to do with the fore and aft movement of the NCX.

Just for clarity, my work place if ~5 miles from Oxygen.

that explains the ultra short turnaround.

I would still change the seat pin for a longer one.

I never feel comfortable with MTB frames where the seat stays are much lower than the top tube. That makes shearing breaks more of a possibility. The bottom of the seat pin should be below the seat stays to avoid this kind of breaking.

[uSER=4366]@d8veh[/uSER] -Ouch! Hope that didn't occur when you were on it. I've added some more photos to give a better view, -you can see the colour change where the upper part of the pin NCX was outside the frame. Your thoughts that it could be related to the fore and aft motion seem sensible.

 

The new one supplied by Oxygen (silver in the photos) appears to be in line with the stays.

 

Any recommendations for an extra long suspension (or not!) seat post?

Edited May 26, 20178 yr by DBye

They look OK. Maybe it was a faulty weld. All it takes is a small undercut at the top and it'll start cracking before long.

 

Like Woosh, I feel happier when the seat pin goes further than all the frame welds.

This is the same bike I am getting soon, can I ask what pannier bag you got for it, I am wanting one which preferably clips/locks onto the pannier but I am not sure until I get the bike what will fit it.

 

I wonder if the design is changed, will I get a slightly thicker seat post too?

Edited May 26, 20178 yr by Mal69

The way it is broken looks like it was a bad tube, maybe the heat of the weld didn't help. Most probably nothing to do with your NCX which is longer and, from my experience, a quality bit of kit compared to some of the pogo stick shock absorbers I have seen. And if they are changing tube thickness my little finger tells me...

Superb customer service, well done Oxygen

[mention=17077]Mal69[/mention] I bought this 3 years ago: http://www.tredz.co.uk/.Avenir-Waterproof-Rear-Pannier-Bag_32894.htm

Its been fantastic for my needs, but you cant lock it to the frame and I don't think they make them anymore -sorry

 

I also get the impression that my frame was an earlier design so you should get a thicker seat post.

Ive just ordered a pair of these, can use them on my current bike, and expect they will fit the most racks so will be good on my next bike.

 

http://www.wiggle.co.uk/?s=dhb+Waterproof+Pannier+22L

 

Very similar to some ortlieb bags I had but half the price, and got pretty good reviews. Easy to clip on and remove.

[uSER=4366]@d8veh[/uSER] -Ouch! Hope that didn't occur when you were on it. I've added some more photos to give a better view, -you can see the colour change where the upper part of the pin NCX was outside the frame. Your thoughts that it could be related to the fore and aft motion seem sensible.

 

The new one supplied by Oxygen (silver in the photos) appears to be in line with the stays.

 

Any recommendations for an extra long suspension (or not!) seat post?

Any idea what the seat post diameter is ? I am thinking of buying one and want to order the correct diameter.

Any idea what the seat post diameter is ? I am thinking of buying one and want to order the correct diameter.

Bike is the Oxygen S Cross CB

Holy thread resurrection Batman!

 

-Long story short, but the generic pogo style suspension seat post Oxygen gave me with the replacement frame has just failed.

 

I'd like (foolishly) to try my NCX again. The NCX needs new bushes and I've ordered a set as per another thread on this forum. I've also noticed that the seat post from Oxygen has an OD of 28.6mm whereas the NCX is 27.2. So the question is, do I need a shim and could this have contributed to the original frame failure?!

 

I'm thinking of one of these (need to double check the dimensions first):

https://www.ebay.co.uk/itm/ALLOY-SEATPOST-SHIM-REDUCER-27-2mm-28-6mm-BICYCLE-SADDLE-STEM-ALLOY-SLEEVE/183128651088?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D50980%26meid%3D60622268ef1e48939a5af6f630ab2c8f%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D183128651088%26itm%3D183128651088&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A48ce3d13-3735-11e8-9c9b-74dbd1806af7%7Cparentrq%3A8b589bc51620a9c51cec2969ffff6a90%7Ciid%3A1

I'd like (foolishly) to try my NCX again. The NCX needs new bushes and I've ordered a set as per another thread on this forum. I've also noticed that the seat post from Oxygen has an OD of 28.6mm whereas the NCX is 27.2. So the question is, do I need a shim and could this have contributed to the original frame failure?!

 

possibly.

From your pics, the NCX seat pin look like 350mm long.

If you set it too high, a shim will make it less stable.

You may be better off with a good sprung post but 28.2mm x 450mm.

28.2 mm is a strange dimension, I am unable to find either shim or seat post that has that diameter...

28.2 mm is a strange dimension, I am unable to find either shim or seat post that has that diameter...

inside 27.2mm, outside diameter is 30.4. this is what he needs:

Personally, I wouldn't recommend any seat pin shim for an aluminium frame because the load os not spread over such a large area, which will accelerate metal fatigue. On some bikes it could keep the twisting force above the frame welds, which would almost guarantee a frame breakage.

Try a Brooks sprung saddle or even just a non sprung Brooks saddle rather than a pogo stick seat post.

Try a Brooks sprung saddle or even just a non sprung Brooks saddle rather than a pogo stick seat post.

A new NCX post will be half price of Brook saddle.