Yesterday the bolt joining my Zero to the seatpost snapped off!!.
Now I’ve got the end bit of the bolt stuck inside the seatpost and of course a broken saddle (the bolt is broken the rest is fine). Does anyone know if you can remove the broken bolt from the top of the saddle and replace it? I’ve got the feeling it might not be possible. Otherwise it looks like I would have to buy a new one (which is really annoying)?
The bolt snapped when I was mounting the 36 : I was loosing the balance a little bit and I pulled the front of the saddle up to regain balance. I am quite light and not very strong so the force I applied was quite minimal…
I have been riding this saddle for a year now and I was very happy with it… It puts me off buying another one if each time the bolt snaps you have to buy a new one…Have never broken a saddle before (seatposts but not saddles…) Has this happened to anyone else (broken bolt in the zero saddle)?
Would be interesting of which property class the original bolt was. I’m sure you won’t break a 12.9 bolt.
As I understand it, it should be possible to remove the bolt wit ha bit of effort. (I have not tried this an do not own one but I remember reading this at the forum)
I was also surprised when it broke. Wasn’t sure what happened at first as the saddle went loose first and then it came off the seatpost. It is meant to be used for all sorts (Muni and tricks) so I am surprised it broke just form mounting the unicycle. I am guessing the constant flexing of the handle bar when riding must have created a weakness in the bolt. I hope I can remove the bolt and replace it. Yesterday I quickly tried to ‘unscrew’ it from the top of the saddle but that doesn’t work. I haven’t removed the cover etc. to see what the mechanism inside is yet…
The small shiny area is probably where the actual break happened, and the duller area is where the crack had slowly progressed before the final break.
So it looks like something that started small, and then grew, due to the flex from weight on the handle, and flex from your weight on the saddle changing as you pedal. And that last mount finally finished it off
Seems to be a bolt made of weak material plus it’s hollow.
Can you find out, of which property class the bolt is? There shall be two numbers on the head, separated by a dot. Maybe its only 4.6 or 5.8.
If you replace it by a 10.9 or even 12.9 you shall be fine.
Thanks for the info. Difficult to see anything from the outside. Not sure yet if it is actually possible to remove and replace the bolt wihout breaking the mechanism inside. I have searched the forum but haven’t found anything yet.
I have emailed the KH company and the UK Unicycle shop to see if it is possible to replace the bolt (also trying to see if this particular breakage of the bolt would be covered by their one year Warranty mentioned in KH website). I guess probably not (bought it a year ago) but just in case I am waiting for them to answer about the Warranty before I try to remove the bolt: I am guessing that you have to remove the cover, and perhaps also the foam? I’ve never opended a saddle before…
I’d say the bolt was probably not tightened enough, which would allow shearing forces to affect the bolt, causing microscopic cracks. These cracks corrode and widen under the influence of the forces until what remains of the bolt (the not rusty part) is no longer strong enough and tears.
Thanks for the pictures.
I’m not entirely surprised; it’s the weakest spot of that construction.
So seems to me like “queued damage” of a number of seat drops,
and already before that a bit of bad-luck with the bolt.
An update for all of you that might have the same problem with the Zero at some point in the future. As there wasn’t any other option I took the cover/foam off the sadle (first time I’ve done it - quite easy, I thought the foam would be glued to the base but it is not - it is only glued to the edges/folds of the saddle). I think there is more than one generation of this saddle, I bought mine a year ago: there is a loose metal plate (kept in place with tape) on top of the bolt and that is what stops the bolt from being pushed up/out from underneath when the foam/cover is in place. So, I’m very glad to say I have now removed the Bolt (is a button head M10 55mm lenght bolt) and I just need to get a new one to replace it.
Glad to hear you successfully removed the bolt. I was a little surprised to see that it was a hollow bolt. Perhaps it was to save weight? I’m guessing that if you replace it with a solid one you will never have that problem again. (That’s what I would do, never mind the extra weight. And I’d probably use a stainless bolt as well.)
Just bought couple of them in the internet (would take me ages to trawl the local shops to find one) and they are stainless steel (hopefully solid). I guess the original bolt was a different material (to save weight as LanceB is saying.). It should take some strength and bad luck to brake this one!