Singlespeed & Fixed Gear - Bye Bye Seat Tube!

So there I was, riding along no handed up a slight hill in downtown Los Angeles when all of the sudden, I wasn't sitting upright, but rather falling backwards. I stuck my right hand out to break my fall, breaking my right thumb at the joint. I get up to find this:

http://img302.imageshack.us/img302/2748/problem12xq.jpghttp://img302.imageshack.us/img302/914/problem26ef.jpg

The seat tube extension broke off at the top tube. Thankfully, Steve Lubanski, owner of my LBS (Open Road Bike Shop) and bicycle inventor (http://www.sidemountpedal.com/) came up with a solution:

http://img171.imageshack.us/img171/9696/solution6fy.jpghttp://img171.imageshack.us/img171/5428/solution27tu.jpg

It's an expander wedge, just like a quill stem. This cost me only $40 (with the little seat adapter thingy) versus quite a bit more to replace the steel tube (reynold 853). Thanks Steve!

EDIT: Does anyone want to buy a CF corima post? Think of it this way, it was STRONGER than reynolds 853 steel, so it's in MIGHTY fine structural condition.

call me traditional, but that looks like a bad idea.
but then again, your orginal seatpost screams bad idea already - 1cm past the max extension line on a seatpost that doesn't pass the top tube......
WTF DID YOU THINK WOULD HAPPEN?



from that last pic it looks like you only have about 3-4 cm on post/quill inserted. who want to take bets on when this is going to happen again?

yikes that is shallow. its only got about an inch in the tube. wow

Icky. Run the proper length seatpost, and stuff like that is much less likely to happen.

It's the little things, people. The little things.

I think the idea behind making the second one that short is so that the wedge (and the the "meat" of the seatpost) is at the seat tube/top tube junction, which is stronger than the paper-thin middle of just the seat tube. How much do you think it would cost to replace the tube? I'm guessing that's the only real solution.

I thought this was a great temporary solution, however.

ah.. you do notice that if the first seat post had been in further.. it would have been in past where it broke off.. thus, adding strength to the tube..instead, being out so far, it was basicall a tube snapping lever.. oops

is that the gt?

is this the reason youve been m.i.a. all summer?

ah.. you do notice that if the first seat post had been in further.. it would have been in past where it broke off.. thus, adding strength to the tube..instead, being out so far, it was basicall a tube snapping lever.. oops

is that the gt?

is this the reason youve been m.i.a. all summer?

That and because he's lame.


And a camp counselor...like me....but lame.

I think the idea behind making the second one that short is so that the wedge (and the the "meat" of the seatpost) is at the seat tube/top tube junction, which is stronger than the paper-thin middle of just the seat tube. How much do you think it would cost to replace the tube? I'm guessing that's the only real solution.

I thought this was a great temporary solution, however.

leave it up to the inventor of one of the dumbest pedal systems ever to come up with that kludge.

you're looking at megabucks to have that replaced. $100+ plus paint if it was lugged. Since it's TIG, then who knows.

how about this...
could you slot the end (the new top) of your seat tube and have a binder welded on?, you might not have to replace the whole tube, provided that that junction isn't at one of the butted bits.

then put in a proper sized seatpost.

Come on guys 'n girls. Do not pull out onto the highway when the 'oil' or 'brake' light are on in the dashboard.

http://img302.imageshack.us/img302/914/problem26ef.jpg

that, right there, is the stupidest thing i've ever seen anyone do with a seatpost/seat tube. the max height line is there for a reason, and i don't think a seatpost that short is designed to be used in a frame where the seat tube extends 3 inches above the top tube.

i think i saw a 3Rensho once with about a foot of seat tube above the top tube. it was also a TT "funny" bike. and also very stupid.

you hardly ever have to worry about a seatpost breaking under normal riding circumstances. even *gasp* a carbon post. the tubing of the frame is much thinner than the tubing used for a seatpost. they're basically indestructable, as long as they're being used properly (not inserted too shallow, not cutting a carbon post, not clamping some dumb QR rack to a carbon post, not exceeding the weight recommendations for said rack-even on an alloy post this is dumb-, the list goes on and on).

that, right there, is the stupidest thing i've ever seen anyone do with a seatpost/seat tube. the max height line is there for a reason, and i don't think a seatpost that short is designed to be used in a frame where the seat tube extends 3 inches above the top tube.

i think i saw a 3Rensho once with about a foot of seat tube above the top tube. it was also a TT "funny" bike. and also very stupid.

you hardly ever have to worry about a seatpost breaking under normal riding circumstances. even *gasp* a carbon post. the tubing of the frame is much thinner than the tubing used for a seatpost. they're basically indestructable, as long as they're being used properly (not inserted too shallow, not cutting a carbon post, not clamping some dumb QR rack to a carbon post, not exceeding the weight recommendations for said rack-even on an alloy post this is dumb-, the list goes on and on).

Thanks. I think at the time I thought that was the maximum you should insert the seat post. It didn't really make sense that it said "max" but meant "minimum." I guess I wasn't considering that it meant "maximum you can pull it out" rather than "put it in."

EDIT: Also, the tube is REALLY REALLY thin at that junction, which is why I didn't just slot it and weld on a binder.

I think at the time I thought that was the maximum you should insert the seat post. It didn't really make sense that it said "max" but meant "minimum." I guess I wasn't considering that it meant "maximum you can pull it out" rather than "put it in."
Must. resist. crude humor.

do you have any shots of the whole bike broken?

EDIT: Also, the tube is REALLY REALLY thin at that junction, which is why I didn't just slot it and weld on a binder.

then you're a bit fux0r3d, eh?

yet you still think it's a good idea to wedge 2 cm worth of post in that exact same place?

then you're a bit fux0r3d, eh?

yet you still think it's a good idea to wedge 2 cm worth of post in that exact same place?
It's a pursuit bike. Of course it's a good idea.

then you're a bit fux0r3d, eh?

yet you still think it's a good idea to wedge 2 cm worth of post in that exact same place?

C'mon, lightning never strikes twice!

Thanks. I think at the time I thought that was the maximum you should insert the seat post. It didn't really make sense that it said "max" but meant "minimum." I guess I wasn't considering that it meant "maximum you can pull it out" rather than "put it in."

EDIT: Also, the tube is REALLY REALLY thin at that junction, which is why I didn't just slot it and weld on a binder.

the max, means max height, as in, this is the maximum height that you should put your seatpost at. you could take it to mean that "this is the maximum amount you should insert the post," but then, that wouldn't make a whole lot of sense, given that most posts are between 250mm and 400mm long.

although, with that corima post, i suppose it could mean that...since the area where it's written is flat, and you wouldn't be able to clamp it. that still doesn't change what sloppy robot said about it being a giant seat tube breaking lever.

the expander wedge thing just looks dangerous as hell. frame: dead. it's gone. PASSED ON! that is an EX-bicycle frame.

"Max" lines are typically too near the end of the post anyhow. You need an inch and half, preferably two inches of post beyond the bottom of the toptube/seatube junction.

That or risk, ah, failure.

How long did that take to break? I mean, did you ride it with a post that short in an extended seat tube frame for long, or just a weekend?

-brad

How long did that take to break? I mean, did you ride it with a post that short in an extended seat tube frame for long, or just a weekend?

-brad

I want to say 9 months, but it might have been a little bit less. This is daily riding, 40 miles or so a day, on average. Also, a lot of sitting up (thus putting pressure on the front of the tube).

I think I'm going to go with the "lightning doesn't strike twice" idea. I don't wear a helmet, and I do stupid sh1t in heavy traffic. Obviously, I don't care about my health, or my bike. Ride on!

wow...have fun...and would you mind if I take out a life insurance policy in your name?

wow...have fun...and would you mind if I take out a life insurance policy in your name?


I've already come to terms with the fact I will have to scrape my best friend's brains off the road one day. It gives me a nice warm fuzzy feeling at night.

When did he do that? Was it Sunday?

leave it up to the inventor of one of the dumbest pedal systems ever to come up with that kludge.

I don't even think this system even could be categorized as a 'pedal'. I almost thought it was some kind of joke, but there appears to be way too much content to be a hoax. Has anyone here actually tried this? I love it when people invent wierd stuff.

I don't even think this system even could be categorized as a 'pedal'. I almost thought it was some kind of joke, but there appears to be way too much content to be a hoax. Has anyone here actually tried this? I love it when people invent wierd stuff.

Well, it has independent lab tests (which is where he got the 3-4% increase in efficiency figure). They're not for sale yet (though he has a bunch of boxes at the shop). I've tried them out, and there's a noticable difference, I think, but it's hard to tell with such a limited testing period. If I started track racing, I would consider asking him for a pair, just for kicks. Anyway, a few people who have ridden them competitively think they're awesome, and I see no technical reason why they wouldn't be better.

This is like Shimano's dynadrive pedals. The downside there was you needed special cranks. That's pretty much why they didn't catch on. I think he might have a good idea, if the marketing goes right.

Can someone provide a link to these said pedals?

I'd just like to say, "CARBON FIBER KICKED STEEL'S ASS!"

*ducks and runs for cover*

this has got to be up there with one of the funniest threads i have ever read...

vomitron,
this now moves you onto my list of 5 bikeforums people i'd like to meet :D




i just hope you stick around long enough for that to become a reality...

Whatever naysayers. I think the expander wedge seatpost is fine. In fact, I've seen a Peugeot frame made for such a seatpost. It had no seatpost clamp.

So yeah, I'd say go with it. What's the worst that could happen? The frame breaks again? Either your frame is trash, or you use the expander wedge and break your frame and your frame is trash, or you use the expander wedge and your frame is perfectly fine. Do it.

Whatever naysayers. I think the expander wedge seatpost is fine. In fact, I've seen a Peugeot frame made for such a seatpost. It had no seatpost clamp.

So yeah, I'd say go with it. What's the worst that could happen? The frame breaks again? Either your frame is trash, or you use the expander wedge and break your frame and your frame is trash, or you use the expander wedge and your frame is perfectly fine. Do it.

or the frame breaks and you bust your other thumb.. and you know what a human is without opposable thumbs.... a complaining monkey

Can someone provide a link to these said pedals?

Click the words 'bicycle inventor' in the first post :rolleyes:

leave it up to the inventor of one of the dumbest pedal systems ever to come up with that kludge.

Pray tell, why do you think it is one of the dumbest systems. It might have issues with lateral stiffnes putting all the stress on this new cleat and a sole of the shoe, the shoes do not seem walkable, but it does effectively lower your BB without reducing ground clerance.

Since when did you all become so bitter and jaded?

"Since when did you all become so bitter and jaded?"

three weeks ago...began the winter job to compliment my regular full-time job...

Since when did you all become so bitter and jaded?

October 3rd, 1989.

I'd just like to say, "CARBON FIBER KICKED STEEL'S ASS!"

*ducks and runs for cover*

and I'm a little concerned that someone from my hometown would troll like this!

and in reality, the statement is fundamentally wrong. All that it shows is that a steel tube with a carbon tube inside is stronger than the same steel tube without a carbon tube inside...big shock there.

Pray tell, why do you think it is one of the dumbest systems. It might have issues with lateral stiffnes putting all the stress on this new cleat and a sole of the shoe, the shoes do not seem walkable, but it does effectively lower your BB without reducing ground clerance.


You can walk just fine in the shoes with the cleats, its made od Ti, unless you are trying to fred flintstone the bike to a screeching halt then you are good.

Yeah, the cleat is "walkable." I mean, it's not walkable like say, a mountain bike shoe, but it's far more walkable than any other road cleat.

As for the seat post, ya'll sound like a bunch of pansies. Have you seen my fscking rear wheel?!? IT'S MADE OF CARBON FIBER, AND HAS BEEN KNOWN TO RANDOMLY EXPLODE.

I obviously have absolutely no regard for my own life.

It's been said that many pro racers choose one size smaller frame then adjust the seat post to fit them, which is more than Max for better aero position. Even then, it's not common that the top of seat tube breaks. I have, however, heard of stories the seat post broke.

From the reason above, I think the frame was defective to begin with.

Hey, anyone knows how that pedal works? Can you pull upwards in it? The system looks like the cleat just slides onto that button thingy from above, no retention...
If there is proper retention, it's not too hard to get out of (I can't see how these two could be achieved) and they managed to make the cleat light and stiff, it's a great improvement. If it's really stiffer than traditional pedals and lowers stacking height by an inch, it'll take the road racing world by storm. (Errr, except that the inventor would need a contract with a pro team to make the amateurs believe it's really that good.)

Yeah, the cleat is "walkable." I mean, it's not walkable like say, a mountain bike shoe, but it's far more walkable than any other road cleat.

As for the seat post, ya'll sound like a bunch of pansies. Have you seen my fscking rear wheel?!? IT'S MADE OF CARBON FIBER, AND HAS BEEN KNOWN TO RANDOMLY EXPLODE.

I obviously have absolutely no regard for my own life.


You keep saying this like its cool to be wreckless with you life. I call dibs on your wetsuit and surfboard...and laptop!

It's been said that many pro racers choose one size smaller frame then adjust the seat post to fit them, which is more than Max for better aero position. Even then, it's not common that the top of seat tube breaks. I have, however, heard of stories the seat post broke.

From the reason above, I think the frame was defective to begin with.


No way. No pro would do such a silly thing as that. Forget the max line, it's irrelevant. The seatpost didn't reach down to the level of the top tube. All the stress was on the seat tube extension, right above a ****ing WELD. Any frame will brake if you do that.

If you pull the seatpost out an inch further than the max line on a normal frame, you're still safe, as the seatpost collar is further down, and the seatpost enters the frame properly. Not on this frame.

To try to add something constructive here:

I don't like the looks of that cob job any more than I like the looks of the original too short seatpost. If you need more seatpost extension, buy a longer seatpost. BUT if you want a cob job that might actually hold your reckless ass, why not insert a thin steel tube into the original seat tube like a patch. It should be the length of the broken peice, plus extend at least 4 inches into the remaining seat tube. then have all 3 pieces brazed together, and slot the top of the new tube to match the seat collar, then use a thinner diamerter seat post that fits the new thicker seat tube. Make sure this one is long enough. It will be heavier than the original frame, but should be lighter and stronger than that crazy seatpost you've got now.

there are seatposts that are made for certain tubesets (i'm thinking certain vitus frames) that are expanding wedge by design... and really damn hard/costly to find. there is no inherent problem with it. of course, you probably want more than an inch or two of the seatpost into the tube.

yea the only thing that raises my eyebrows in this story is that your lbs just had one right there. i was scouring for one once, to no avail.

1986 - Whiskeytown, Cindy Whitehead breaks her seatpost and rides over 40 miles to win.

Let's all get rid of our seatposts immediately.

yea the only thing that raises my eyebrows in this story is that your lbs just had one right there. i was scouring for one once, to no avail.


He didn't. It had to be machined specially for him. Took like five months to come up with that as a solution and have it made. It was far from an overnight job.

He didn't. It had to be machined specially for him. Took like five months to come up with that as a solution and have it made. It was far from an overnight job.

WOW REALLY? I woulda just fixed the frame, or replaced it.

WOW REALLY? I woulda just fixed the frame, or replaced it.

Well, it is a unique one of a kind olympic track frame, so I'm not sure if its replacable or not. Fixing it is a more expensive option, not open to those of us that work with children.

As for the seat post, ya'll sound like a bunch of pansies. Have you seen my fscking rear wheel?!? IT'S MADE OF CARBON FIBER, AND HAS BEEN KNOWN TO RANDOMLY EXPLODE.

I obviously have absolutely no regard for my own life.
And fixed via the bumbike method.