# Steerer tube extension - is it safe?



## Kodi Crescent

I was in the LBS this afternoon. This guy came in with this really nice road bike that he bought online for a great deal. The bike was really nice.

He was an older, heavier guy, and I think this may have been a race bike. He was having troubles with fit (go figure, but he got a great deal on the bike).

The LBS staff was trying to install a steerer tube extension on the bike. It was a carbon frame, carbon fork, but the fork had an aluminum steerer tube. I watched the LBS guy putting it on, and I asked:
(Me, asking tentatively) - "Is that safe?"
(LBS guy, answering confidently) - "Oh, it's very safe."
(Me) - "I don't think it is."

I went and mentioned to the store manager that those steerer tubes are limited to about 5 cm extension, or else the torque on them could crack them and cause a failure. I asked him to go back and investigate, then I left.

Are those steerer tube extensions safe?


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## Kontact

A steerer stack limit of 4cm is generally accepted for carbon steerers. Steel steerers don't really have a limit, and aluminum is a relative unknown. But aluminum should be stronger than carbon for clamping.

What lead you to believe you knew better than the shop staff?


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## tihsepa

Kontact said:


> What lead you to believe you knew better than the shop staff?


Rep power of 1?

Geeze, what's a matter you?


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## brianmcg

You are wrong. There should be no issues with the extension on an al. steerer.

But on anothet note, congratulations on earning a new nickname from the shop staff.


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## Kontact

tihsepa said:


> Rep power of 1?
> 
> Geeze, what's a matter you?


From what I can tell, rep and intelligence/experience are just as likely to have an inverse relationship. The lounge is pretty much a celebration of this concept.


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## tihsepa

Kontact said:


> From what I can tell, rep and intelligence/experience are just as likely to have an inverse relationship. The lounge is pretty much a celebration of this concept.


But the other guy says the extension of fine so............


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## Kodi Crescent

Kontact said:


> A steerer stack limit of 4cm is generally accepted for carbon steerers. Steel steerers don't really have a limit, and aluminum is a relative unknown. But aluminum should be stronger than carbon for clamping.
> 
> What lead you to believe you knew better than the shop staff?


Because I just went through this whole thing with trying to get a bike to fit correctly. One of my options was to replace the fork with one that had an uncut steerer. I was advised against using a much longer steerer due to torque / cracking issues.

Adding a steerer extension was never suggested as an option to fix a fit problem, probably for the reason I mentioned above. 

In regards to the shop staff, I don't have a lot of faith in shop staff, unless they run the shop and its their rear end on the line. This happened to be one of the larger national shops that serviced a lot of beginner clientele -- I don't expect the staff to be world class mechanics.


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## MR_GRUMPY

But it's not safe from ridicule.

Those extenders belong on comfort bikes, not race bikes.
.
.
.


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## speed metal

I had an similar experience. My son plays High School Football and the head coach called a running play on 3rd &10. I thought a passing play was in order. So I called the athletic director at home and told him he might want to come to the game cause the coach isn't calling the proper plays.


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## tihsepa

Nevermind, it will be fine.


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## Dave Hickey

tihsepa said:


> Nevermind, it will be fine.


holy sh!t..............:thumbsup:


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## bikerjulio

Sometimes I think this is some kind of joke. And then I realize it isn't.

Is that a Trek?


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## robdamanii

tihsepa said:


> Nevermind, it will be fine.


He belongs in this thread.


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## tihsepa

bikerjulio said:


> Is that a Trek?


Yep, probably Bontrager extentions.


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## Kontact

Kodi Crescent said:


> Because I just went through this whole thing with trying to get a bike to fit correctly. One of my options was to replace the fork with one that had an uncut steerer. I was advised against using a much longer steerer due to torque / cracking issues.


So, because one shop said that something on your bike is bad idea, that means you are now more knowledgeable than the staff at another shop?

I'm no fan of extensions, but unless you have something more concrete than advice you received once, it was kind of presumptious to attempt to "tell on" the mechanic staff.


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## Rollo Tommassi

*Omg*

that big "N" on his jersey is for NO NO NO NO NO NO!!

However, back to the OP's concern, no there isn't inherently anything UNsafe about a steerer extension. On the other hand, I would have no hesitation as a shop employee to tell him that:
A: no matter how 'good a deal' the big is, it is not the right bike for him, and
B: IF the mechanic says "ok" It will cost you at least $100 for us to install (new cables, housing, bar tape, yada yada) 
C: Frankensteining that bike will affect handling,
D: We would ask that you sign this dated letter absolving us from all liabilty

I've had this conversation in the past with a customer, and they ended up returning the "good deal" bike and bought a more appropriate and properly fitting bike from us.

Had a similar conversation with a gentleman who had a 60cm Madone with a steerer extension. Our conversation ended with him putting down a deposit with me for a custom Moots.

So, my point is that the LBS is doing a disservice to the customer by:
A: NOT selling him/her on the expertise, knowledge and services of their shop,
B: Allowing him/her to have a crappy experience on a bike. That, I think, is the worst part of it all. :cryin:


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## FBinNY

Is it safe? probably yes.

Total bending moment on the extended steerer is a function of stack height and handlebar extension. The measurement that counts is the distance from the handlebar to the headset top assembly. There are other factors involved including how precisely the spacers are made, and the angle that the rider pulls on the bars. 

In any case, the extender fits down into the steerer and reinforces it pretty well. If the base of the extender is below the headset bearing the arrangement is probably stronger than direct mounting. 

If the bottom is above the headset, it's the same as without except for the longer moment arm, but with a short stem and a rider who doesn't work the bars hard hill climbing is probably no worse than the use of carbon parts anywhere else on the bike.


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## Kodi Crescent

This definitely wasn't a power rider. He was an old, overweight yuppie who got a good deal on a closeout boutique bike online. He had the shop build it from the box for him.The extender would have been mounted above the spacer and headset stack, probably 5cm above the headset. 
The stem was probably 100 - 110 mm, 0-6 degree rise.

I'm sure there was no discussion on changing some of the easier variables such as stem length and rise first. The customer probably told the sales guy about what he wanted, and the sales guy tried to accommodate the guy without having him get on a bike and see.

I wanted to step in and tell the guy that was the wrong bike for him, but it just wasn't my place. I'll probably find that bike on Craigslist within the next year.


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## Kodi Crescent

Kontact said:


> So, because one shop said that something on your bike is bad idea, that means you are now more knowledgeable than the staff at another shop?
> 
> I'm no fan of extensions, but unless you have something more concrete than advice you received once, it was kind of presumptious to attempt to "tell on" the mechanic staff.


So nothing about this situation raises any red flags for you? Would you have risked your bottom line and reputation on the safety of that deal?

There was no risk to me if that guy crashed and ended up in the hospital. It wouldn't be my pain, suffering, or attorney fees in the deal. However, I did feel I had a moral obligation to point out something that seemed suspect and potentially dangerous. Call it being a tattle-tale if you like. I call it being ethical and responsible.


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## Kontact

Kodi Crescent said:


> So nothing about this situation raises any red flags for you? Would you have risked your bottom line and reputation on the safety of that deal?
> 
> There was no risk to me if that guy crashed and ended up in the hospital. It wouldn't be my pain, suffering, or attorney fees in the deal. However, I did feel I had a moral obligation to point out something that seemed suspect and potentially dangerous. Call it being a tattle-tale if you like. I call it being ethical and responsible.


There are two issues here:

1. Is this safe? On an aluminum steerer, probably. 

2. Do you have the depth of knowledge to tell professionals how to do their job? See 1.


You can only argue the ethics of speaking up if you actually have the information to speak up about. If not, you are being a busybody.

Illustrated:
We had a customer buy a $5000 bike the other day. When asked if he wanted a lighter wheel option, he told the mechanic that lighter wheels make the bike less stable, since bikes are kept upright by centrifugal force (they aren't). Imagine if he started doing his 'ethical duty' by warning someone else in the store looking at light wheels to avoid them? 

His microscopic bit of knowledge on the topic is fine for him to act on, but screwing with other people's bikes and jobs is not.


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## FBinNY

Kodi Crescent said:


> So nothing about this situation raises any red flags for you? Would you have risked your bottom line and reputation on the safety of that deal?


Yes, so far there is nothing about this that raises a red flag for me. As it stands now, I don't have enough information to second guess the judgement of the mechanic in the field. It's possibly that he's going too far, and it's equally possible that it's perfectly safe. the devil here is in the details.

It's always easy to say something may be unsafe. After all there's no way to determine the consequences of an accident that might have happened. Following that logic to it's conclusion nothing is safe, so we need to make judgement calls. And those need to be based on real information about the particulars.


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## Kodi Crescent

Kontact said:


> There are two issues here:
> 
> 1. Is this safe? On an aluminum steerer, probably.
> 
> 2. Do you have the depth of knowledge to tell professionals how to do their job? See 1.
> 
> 
> You can only argue the ethics of speaking up if you actually have the information to speak up about. If not, you are being a busybody.
> 
> Illustrated:
> We had a customer buy a $5000 bike the other day. When asked if he wanted a lighter wheel option, he told the mechanic that lighter wheels make the bike less stable, since bikes are kept upright by centrifugal force (they aren't). Imagine if he started doing his 'ethical duty' by warning someone else in the store looking at light wheels to avoid them?
> 
> His microscopic bit of knowledge on the topic is fine for him to act on, but screwing with other people's bikes and jobs is not.


I bet you work at "Cycling Spoken Here". Am I correct?


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## Winters

Thank goodness Navy Beat Army yesterday, else this photo would have ruined the rest of 2011 for me.

On a serious note, I was at my local LBS today and one of the wrenchers there has about a 3" extension above the stem on his bike. Is he just "borrowing" a stem and doesn't want to cut It ?


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## speed metal

This thread is way more awesome than the crankset preferance thread. I bet Kodi Crescent is a Tebow fan also!


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## Kodi Crescent

speed metal said:


> This thread is way more awesome than the crankset preferance thread. I bet Kodi Crescent is a Tebow fan also!


I hate football, especially the Denver Broncos.


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## flatlander_48

Just out of curiosity, I would say that this issue is not a bike fit problem. It sounds more like a rider flexibility problem and they are trying to get the bike to work around that. Anybody else read it this way?


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## Mr. Scary

Kontact said:


> A steerer stack limit of 4cm is generally accepted for carbon steerers. Steel steerers don't really have a limit, and aluminum is a relative unknown. But aluminum should be stronger than carbon for clamping.
> 
> What lead you to believe you knew better than the shop staff?


Because most shop staff are not engineers, that's why...


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## Kontact

Mr. Scary said:


> Because most shop staff are not engineers, that's why...


That's irrelevant. 

No one in this story is an engineer. The people who are the engineers are the ones who made the fork and the extensions and wrote the installation manuals that the mechanics read.


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## sp3000

Kontact said:


> That's irrelevant.
> 
> No one in this story is an engineer. The people who are the engineers are the ones who made the fork and the extensions and wrote the installation manuals that the mechanics read.


I didn't know that bike shop mechanics could read? ....

oooooh.. just kidding, just kidding, I couldn't resist.

But seriously I have seen some awful stuff happen at the hands of bike shop mechs. Awful awful things... I now do everything myself.:thumbsup:


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## Jesse D Smith

Kodi Crescent said:


> This definitely wasn't a power rider. He was an old, overweight yuppie who got a good deal on a closeout boutique bike online. He had the shop build it from the box for him.The extender would have been mounted above the spacer and headset stack, probably 5cm above the headset.
> The stem was probably 100 - 110 mm, 0-6 degree rise.
> 
> I'm sure there was no discussion on changing some of the easier variables such as stem length and rise first. The customer probably told the sales guy about what he wanted, and the sales guy tried to accommodate the guy without having him get on a bike and see.
> 
> I wanted to step in and tell the guy that was the wrong bike for him, but it just wasn't my place. I'll probably find that bike on Craigslist within the next year.


You seem to know an awful lot about this transaction including the customers ability level, social standing, where he got the bike, etc. Just be aware of all the assumptions you're making. 
The stem was probably...
I'm sure there was no....
The customer probably....
I bet you work at.....

You need more information, less disinformation, and more experience before you go around telling shop mechanics how to do their job. It interferes with their work and it can get you a reputation as a pain in the ass. Then you get disillusioned when you go into the shop and get no attention, no service, no deals, and no advice.


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## Kodi Crescent

Jesse D Smith said:


> You seem to know an awful lot about this transaction including the customers ability level, social standing, where he got the bike, etc. Just be aware of all the assumptions you're making.
> The stem was probably...
> I'm sure there was no....
> The customer probably....
> I bet you work at.....
> 
> You need more information, less disinformation, and more experience before you go around telling shop mechanics how to do their job. It interferes with their work and it can get you a reputation as a pain in the ass. Then you get disillusioned when you go into the shop and get no attention, no service, no deals, and no advice.


Speaking of assumptions, everyone is assuming that this was the MECHANIC helping the guy. It WAS NOT. It was a member of the SALES FLOOR staff. A CASHIER.


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## Kodi Crescent

Kontact said:


> That's irrelevant.
> 
> No one in this story is an engineer. The people who are the engineers are the ones who made the fork and the extensions and wrote the installation manuals that the mechanics read.


I'm an engineer.

Since I'm being accused of making assumptions, I'm going to assume that if we contacted the engineers who designed the fork they would not recommend that an extension be added for a variety of reasons. Liability is probably at the top of the list.

The assembly may not fail, but if it does, the consequences could be disastrous. Better to err on the side of caution.


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## Kontact

Kodi Crescent said:


> I'm an engineer.
> 
> Since I'm being accused of making assumptions, I'm going to assume that if we contacted the engineers who designed the fork they would not recommend that an extension be added for a variety of reasons. Liability is probably at the top of the list.
> 
> The assembly may not fail, but if it does, the consequences could be disastrous. Better to err on the side of caution.


This was a 1 1/8" extension, and 1 1/8" steerer tubes are all either carbon or aluminum these days. These extensions are still being produced. Are you saying an engineer designed this, but never to be used?

BTW, nearly everybody these days is fat, and the skinny ones are not often the ones buying equipment to sit up straighter. I really don't understand who or what you think this device was built for. It isn't a candlestick.


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## DaveG

*new benchmark*

This is the gold standard against which all future ridiculous handlebar extensions will be measured


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## Kodi Crescent

Kontact said:


> This was a 1 1/8" extension, and 1 1/8" steerer tubes are all either carbon or aluminum these days. These extensions are still being produced. Are you saying an engineer designed this, but never to be used?
> 
> BTW, nearly everybody these days is fat, and the skinny ones are not often the ones buying equipment to sit up straighter. I really don't understand who or what you think this device was built for. It isn't a candlestick.


You are an argumentative type, aren't you? That's why I asked if you worked at that particular shop. I see you are in the Triangle area. I'm curious as to which shop so I can stay out of it.

Engineers can design all sorts of things, but that doesn't mean that mixing them is a good idea. Just because something is made for a bike and has a certain dimension, doesn't make it compatible. 

Engineers designed clamping bike racks and clamping work stands, but that doesn't mean I can clamp them on my engineer designed carbon frame.

One engineer designed a threaded assembly and another engineer designed a tool. But if I use said tool in a manner inconsistent with the specs of the threaded assembly, it will fail. Both were designed by engineers.

So if you rig this assembly up, and it fails, who is ultimately responsible for the consequences? The folks that make the steerer tube extender? That part won't fail, unless it fails at the clamp/screw threads. The fork will be the failure point. It is being used in a manner inconsistent with how it was designed. That manufacturer will deny any claim due to this.

In case of a failure, the store will ultimately be held responsible for the bad advice.
That doesn't help our new cyclist, who should have been advised that this was the wrong bike for him and that he is better off looking for the bike that best fit him.


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## orange_julius

Kodi Crescent said:


> You are an argumentative type, aren't you? That's why I asked if you worked at that particular shop. I see you are in the Triangle area. I'm curious as to which shop so I can stay out of it.
> 
> Engineers can design all sorts of things, but that doesn't mean that mixing them is a good idea. Just because something is made for a bike and has a certain dimension, doesn't make it compatible.
> 
> Engineers designed clamping bike racks and clamping work stands, but that doesn't mean I can clamp them on my engineer designed carbon frame.
> 
> One engineer designed a threaded assembly and another engineer designed a tool. But if I use said tool in a manner inconsistent with the specs of the threaded assembly, it will fail. Both were designed by engineers.
> 
> So if you rig this assembly up, and it fails, who is ultimately responsible for the consequences? The folks that make the steerer tube extender? That part won't fail, unless it fails at the clamp/screw threads. The fork will be the failure point. It is being used in a manner inconsistent with how it was designed. That manufacturer will deny any claim due to this.
> 
> In case of a failure, the store will ultimately be held responsible for the bad advice.
> That doesn't help our new cyclist, who should have been advised that this was the wrong bike for him and that he is better off looking for the bike that best fit him.


Rather than arguing in abstract, why don't you find a fork manufacturer's instruction that states the limit that is exceeded in this case? Out of curiosity, I looked at Bontrager's fork installation document and it doesn't give any limits.

I think you are opening new fronts of argument that are not relevant to the discussion, at least I don't see how they are. I thought the argument was simply about whether a particular installation scenario is dangerous, which you helpfully suggested meant that it exceeds a specification.


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## danl1

flatlander_48 said:


> Just out of curiosity, I would say that this issue is not a bike fit problem. It sounds more like a rider flexibility problem and they are trying to get the bike to work around that. Anybody else read it this way?


Not so much. That's as much as saying that there should only be one size of bicycle, and everyone should just get comfortable as best as they can.

The bike should be adapted to the rider, not the rider to the bike. And if you are doing it right, the bike is close enough that only minor changes are needed. 

What I read in this case is that someone simply bought the wrong size bike, because it was a 'good deal.' I wonder how many suits he has in his closet that are three sizes too small, but were a 'good deal.'


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## danl1

*Another thought on the matter...*

Hands Up! Adjusting Handlebar Stem Height on Your Bicycle


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## Kontact

Kodi Crescent said:


> You are an argumentative type, aren't you? That's why I asked if you worked at that particular shop. I see you are in the Triangle area. I'm curious as to which shop so I can stay out of it.
> 
> Engineers can design all sorts of things, but that doesn't mean that mixing them is a good idea. *Just because something is made for a bike and has a certain dimension, doesn't make it compatible. *
> 
> Engineers designed clamping bike racks and clamping work stands, but that doesn't mean I can clamp them on my engineer designed carbon frame.
> 
> One engineer designed a threaded assembly and another engineer designed a tool. But if I use said tool in a manner inconsistent with the specs of the threaded assembly, it will fail. Both were designed by engineers.
> 
> So if you rig this assembly up, and it fails, who is ultimately responsible for the consequences? The folks that make the steerer tube extender? That part won't fail, unless it fails at the clamp/screw threads. The fork will be the failure point. It is being used in a manner inconsistent with how it was designed. That manufacturer will deny any claim due to this.
> 
> In case of a failure, the store will ultimately be held responsible for the bad advice.
> That doesn't help our new cyclist, who should have been advised that this was the wrong bike for him and that he is better off looking for the bike that best fit him.


I don't know what the Triangle area is - I'm in Wisconsin.

I also don't understand what you're getting at with the highlighted section. You said that the guy's bike had an aluminum steerer - the most conservative steerer material available in 1 1/8". If the extender wasn't for this guy's bike, who's bike is it for? Are you talking about a weight limit or bar width limit? 


The other thing to consider here is that the extender connects to the steerer tube the same way a stem with no spacers does - all the way at the bottom. So if spacers are an issue, this system has none. 

The only other consideration is leverage. These extenders add 7cm of height, but Mr. Pythagorus says that on a 42cm bar that only increases the lever arm from hoods to headset by 1.1cm. If the leverage of adding this extender is the same as simply going from a 42 to a 44cm bar, what is you _engineering_ issue with it?


BTW, you posted this, not me. If you don't want an argument, don't post something wrong and then insist you're right about it.


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## Kodi Crescent

danl1 said:


> Hands Up! Adjusting Handlebar Stem Height on Your Bicycle


Sheldon shows that, but we don't know whether he is mounting that on a steel steerer tube or not.


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## Kontact

Kodi Crescent said:


> Sheldon shows that, but we don't know whether he is mounting that on a steel steerer tube or not.


We don't, but Sheldon specifically says "metal 1 1/8" steerers", which means that he doesn't think it matters which kind of metal it is.


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## danl1

Step one: Find an online seller with a wide selection. Someone that stocks from QBP will do.
Step two: Notice that these are available from multiple manufacturers.
Step three: Consider America's litigious environment.

They may not be the best idea on the planet, for a few reasons, but yeah, they are reasonably safe when used according to directions.


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## Broozer59

This is an old thread and I noticed no one here has actually installed or used a steerer extension. Good news! I have one on an aluminium frame Malvern Star oppy A4. The stock frame is very racey (small headtube). Bike is a lot more comfortable and the geometry is now more like an endurance bike when on the hoods and of course you still have the drops when you need some speed. This was my first race bike and I bought the large size (56cm top tube) on the recommendation of the bike shop owner. I'm 185cm tall and 55 when I bought it. I have also installed a shorter stem so no problem with cables. In retrospect a more comfortable geometry would have been the way to go but because of my inexperience I didn't know any better. I assumed race bikes were meant to be uncomfortable!
Extender works fine and is solid. I've completed 100km plus rides on this bike without any problems.


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## Finx

Broozer59 said:


> Extender works fine and is solid. I've completed 100km plus rides on this bike without any problems.


Working fine or not, that bike is three sizes too small for you...


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## No Time Toulouse

Are we still posting "April Fools" posts? It's the 6th already....


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## duriel

That posted bike looks like it has 'double' extension on the stem & that seat angle, OMG, I would feel like I would slide off it and onto the top tube if I lifted both hands from the handlebars!!!!


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## Lombard

A stem extender is OK unless you have a carbon steerer, then it's dangerous. If you are looking to get some handlebar height, why are your bars tilted so low. You can get "free height" by tilting them up. Better yet, get bars with a shorter reach and a stem with a greater rise.

This being said, as Finx said, the bike looks too small for you anyway. These "fixes" are all a Band-Aid on a broken leg.

And as duriel implied, your saddle angle looks like you would struggle to not slide forward. I can't imagine that's very comfortable.


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## Tom Kunich

tihsepa said:


> Rep power of 1?
> 
> Geeze, what's a matter you?


Anyone is entitled to an opinion. But an educated opinion is a real one and an uneducated opinion is simply noise. Aluminum steering tubes are so strong that their height is unlimited by length. And you can use those punch in Cap screws which you cannot do with carbon fiber. In steering tube extenders I would hesitate to extend a steering tube more than 5 cm but I wouldn't worry about the length of the steering tube itself. There is a worry about the head tube though since that is a source of failure in some bikes.


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## Tom Kunich

Kodi Crescent said:


> So nothing about this situation raises any red flags for you? Would you have risked your bottom line and reputation on the safety of that deal?
> 
> There was no risk to me if that guy crashed and ended up in the hospital. It wouldn't be my pain, suffering, or attorney fees in the deal. However, I did feel I had a moral obligation to point out something that seemed suspect and potentially dangerous. Call it being a tattle-tale if you like. I call it being ethical and responsible.


Even if your opinion is hogwash, if you have the idea that it is your obligation, that is enough to prevent me from criticizing you over it. Though being me I have no problem criticizing your idea of the failure points.


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## No Time Toulouse

Good old Tom Kunich, answering a 10 year-old post. Still on top of things, I see...


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## Lombard

No Time Toulouse said:


> Good old Tom Kunich, answering a 10 year-old post. Still on top of things, I see...


Looks like he was re-banned already. Don't know what he posted elsewhere. These two posts of his don't seem ban worthy.


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## ogre

Lombard said:


> Looks like he was re-banned already. Don't know what he posted elsewhere. These two posts of his don't seem ban worthy.


He started a thread with a specific bike shop mentioned in the title and how bad they ducked. Then the body of the post was a diatribe on their mask policy. cx gave a very polite response about the state of things right now, then I blasted cx for not telling him to take that crap to PO. I don’t see that thread anymore, most likely got nuked because of the inflammatory crap in the title with a specific LBS mentioned.


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## Lombard

ogre said:


> He started a thread with a specific bike shop mentioned in the title and how bad they ducked. Then the body of the post was a diatribe on their mask policy. cx gave a very polite response about the state of things right now, then I blasted cx for not telling him to take that crap to PO. I don’t see that thread anymore, most likely got nuked because of the inflammatory crap in the title with a specific LBS mentioned.


Yikes! Yep, the mods did the right thing.


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