Road Bike, Cycling Forums banner

1 - 20 of 47 Posts

·
- I -
Joined
·
812 Posts
Discussion Starter · #1 ·
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?
 

·
Happily absent RBR Member
Joined
·
3,940 Posts
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?
 

·
Man, I'm Awesome
Joined
·
2,175 Posts
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.
 

·
Not a rocket surgeon.
Joined
·
9,402 Posts
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............
 

·
- I -
Joined
·
812 Posts
Discussion Starter · #7 ·
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.
 

·
Banned forever.....or not
Joined
·
24,410 Posts
But it's not safe from ridicule.

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

·
Registered
Joined
·
157 Posts
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.
 

·
Registered
Joined
·
7,492 Posts
Sometimes I think this is some kind of joke. And then I realize it isn't.

Is that a Trek?
 

·
Happily absent RBR Member
Joined
·
3,940 Posts
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.
 

·
Deliciously Ironic
Joined
·
1,006 Posts
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:
 

·
Registered
Joined
·
1,846 Posts
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.
 

·
- I -
Joined
·
812 Posts
Discussion Starter · #18 ·
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.
 

·
- I -
Joined
·
812 Posts
Discussion Starter · #19 ·
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.
 

·
Happily absent RBR Member
Joined
·
3,940 Posts
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.
 
1 - 20 of 47 Posts
Top