Today I broke 4th bike in last 3 years. This time frame cracked under the seat. It was a heavy touring bike (Riverside Touring 900). Only 14 months old, 18k km.
– Last year seatpost broken,
– Two years ago – broken rear hinge on a Brompton,
– 3 years ago – broken Cane creek suspension seatpost (tube, not a mechanism).
I'm 72 kg, I cycle 90% on asphalt, 10% on light gravel. Bikes are not overloaded. I pay attention not to overtight a seatpost clamp. Seatposts are far away from limit line.
During cycling I see some bending movement of seatpost but I assume it's normal.
From what I've read, seatpost sometimes break, but not that often.
What's wrong with me?
by szulski
20 Comments
Are you riding too small a bike and then running seat posts at max and/or seat all the way back?
It’s all about leverage and stretching limits adds stress.
Only other thing I could see being an issue is if you have your saddle set very far back on your seatpost, that will also potentially increase the lever arm on the frame and post beyond design limits.
That being said you could just have lost the lottery on this.
are you sitting hard over the bumps, not using your legs for suspension?
That’s very unusual. The only thing that comes to mind is maybe you sit very upright with the saddle all the way back on the rails, with a backpack? I’m 110 kg and I’ve never seen that happen.
> far away from the limit line
That doesn’t look like anything but a seat post that is sticking too far out, like the limit line is too far up from the top of the seat tube 🥴🤷🏻♂️
I would consider your riding style. Braking and hitting potholes at the same time, not using your legs as suspension could be contributing factors
Post a picture where we can see this joint and the entire seat post.
Where is the max insert line on the seat post? This absolutely looks like a seat post with insufficient insertion.
What does “not overload” mean to you? It seems to be only rated for 40kg on rear rack. If you’re seeing post flexing you are definitely adding more stress to the seat tube which is evident from the location of the crack. Also, do you ride over rough surfaces while seated? I hate to say it but at your rate of 4 frames over 3 years it’s very likely how you are using the bike. 72kgs is not very much body weight so I’d consider evaluating how you ride or treat the bike. I knew a guy that while only 6ft tall and 200lbs he was always breaking stuff on his bike because he rode it very rough, never cared about hitting bumps let alone standing while riding rough terrain. For reference he rode a steel stumpjumer with 36 count double walled rhino rims and he could never keep them true. Saddle rails bending, tires with side wall gashes pretty much anything would be replaced by the end of the season.
You’ve had very different failures each time, so I doubt it’s a you problem. Suspension seatposts can be unreliable, and Bromptons are their own thing and only barely related to normal bikes.
If you’re sure that you’re respecting the minimum insertion required by both your frame and your seatpost, and are tightening the bolts with a torque wrench I do see how these failures are anything more than bad luck.
If you’re putting 18k km on a bike in 14 months, that’s a lot of wear. Considering most people don’t ride that much in 5 years, you might just simply be reaching the end of the bikes lifecycle quickly? If you are the common factor between all bikes then you are the issue.
This looks like a frame issue if you aren’t doing something really weird or wrong. The two other posts kinda does make a pattern. Probably a good dose of bad luck. Only thing I haven’t seen mentioned, is your pedal stroke very bouncy, or do you do a lot of seated pedaling on rough surfaces (cobble, washboard, etc.? Not gonna break anything on its own, but could accelerate inevitable failures. Basically everything made of aluminum will fatigue and break eventually, but even the weight weeniest stuff should go more than 18k.
I’m just wondering, is this guy too big for his XL frame? Based on your weight, I can’t imagine that being the case, but this kind of crack seems to be from overleveraging a seat that is too high up and too far back.
That’s really fucking wierd, dude. In 2007 I bought a Trek Pilot 2.1 (aluminum frameset, endurance geometry) and in spring of 2010 I started crit racing and road racing on it, despite it not being a race bike. Used it for that for *years*, training hard and racing hard, and I’m about 200 pounds plus or minus all the time. Eventually it developed a cracked weld in the bottom bracket area of the seat tube, but it took *years*.
Meanwhile you’re at least 40 pounds lighter than me and you’ve killed 4 framesets, and you don’t sound like you race at all?
*SHRUG* I got no answers for you, other than ‘warranty the bike’. Maybe try a different brand, if you keep buying the same brand bikes, maybe they don’t build good framesets.
There is a reason why old school frames when they’re fitted to the rider were a lot taller at the seatpost area than what they are now.
You didn’t have to jack up the seat post back then
River side is a decathlon bike and a pretty cheaply manufactured frame… I would say it’s the frame, and everything else you’ve experienced is some what “normal” considering the amount of cycling your doing. I expect at least every 2,000-4,000km something will go wrong with components. Even less time for cheap ones
You might be unlucky or you might be reaching the fatigue limits of aluminum given your time/distance/load. You ride much more than the average enthusiast.
If it’s in your budget you could consider a as stout carbon frame, it doesn’t fatigue the same way aluminum does.
Random parts are going to break with how much you ride, no way around that. Frame should last longer.
I think you need a good steel bike, properly fitted, and maybe an extra long seat post just to be safe. Be sure to tighten to proper torque—it really matters. And always give your main components a good look-over every 6 months or so. You ride a lot.
I’ve went from 80 to 100kg in recent years and I haven’t actually ever broken anything … (touch wood) … but when I ride I’m very conscious of riding through potholes so I always go around or unload the bike if I have to go through them, since I know no international testing standard would be able to replicate what British roads are like
You ride Giant bikes?