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Discussion Starter · #1 ·
Hey Guys and Gals
This is my first post on here so be esay on me>
Bought my first rode bike last year Giant OCR alliance
I have about 2000 miles on it and I have noticed my front crank teeth
are wore way down.
Its a Shimano tiagra FC 4550
I have been looking On line and I see that the FC 4650 seems to be a lot cheaper.
Can anybody tell me what the difference is??
Is it better just ahve a new gear put on or buy new crankset!!

thanks for any info
 

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Funny, 2000 miles shouldn't wear down the teeth. Not in my opinion.

Does it look worn to you or does a mechanic say its worn?

And chain rings are normally alot cheaper then a new crankset

Bill
 

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Shimano spends alot of time shaping the teeth for good shifting. This machine work is often mistaken for damage or wear. I would bet there is no issue with your crankset.
 

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If some of the teeth seem worn-down to you and others don't, it could be that the crank came that way from the factory. Sometimes the short or blunt teeth are all in a row, like three of them or so. Such an arrangement is called a "shift gate" and allows for easier shifts under power.

Edit: tihsepa got there ahead of me.
 

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Discussion Starter · #5 ·
Well
I am a ford techician but I have not worked on any bikes like these !!
To me it looks like the 50 tooth gear teeth are way smaller and look worn to me than the smaller gear
But maybe they are suppose to look like that!!
ill take it to the bike shop and have them look at it!!
 

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Never ever use the term "rode bike"......It's "road bike".

I'll pretend that this was a spelling mistake.

That is all.
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PS Crank is probably OK. Most chainrings last for years and years. (unless you ride all day at 400 watts)
.
.
 

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Chainring teeth wear where they are in forceful contact with the chain rollers. So they don't get shorter; they acquire a profile that looks like a hook or a sharkfin, rather than the symmetrical shape they start with.
View attachment 281879
 

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Well
I am a ford techician but I have not worked on any bikes like these !!
To me it looks like the 50 tooth gear teeth are way smaller and look worn to me than the smaller gear
But maybe they are suppose to look like that!!
ill take it to the bike shop and have them look at it!!
The small ring and bike ring don't have the same teeth and they are supposed to look different. Unless you are lubing your chain with diamond dust your ring is not worn out after 2000 miles.

Here's a picure of your cranksete unused so you can see that the two rings don't look alike: https://www.nashbar.com/images/nashbar/products/large/SH-FC4550-NCL-TOP.jpg
 

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The small ring and bike ring don't have the same teeth and they are supposed to look different.
Good point. On that note, people who are not that familiar with modern bicycles often remember the looks of old-school chain wheels, which had much longer teeth. A close modern equivalent to those is the still-current (FC-7710) Dura-Ace track crank with it's "old-timey" long teeth that do not need to be chopped off for easier gear-shifting.
 

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At 2000 miles, you are due for a new chain. However, your chain ring is designed with some teeth different from others. This aids with shifting.
Only true if you ride in crappy conditions and don't take care of your chain. A moderately maintained chain will last longer than that. And a well maintained chain will last much longer.
 

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If some of the teeth seem worn-down to you and others don't, it could be that the crank came that way from the factory. Sometimes the short or blunt teeth are all in a row, like three of them or so. Such an arrangement is called a "shift gate" and allows for easier shifts under power.

Edit: tihsepa got there ahead of me.

This is correct (I hope) Here is a pic of my brand spanking new FSA crank.


<a href="https://s7.photobucket.com/user/bcsinflight/media/DSCF7209_zps408a3281.jpg.html" target="_blank"><img src="https://i7.photobucket.com/albums/y277/bcsinflight/DSCF7209_zps408a3281.jpg" border="0" alt=" photo DSCF7209_zps408a3281.jpg"/></a>
 

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Its fine.
+1. Those two short teeth in a row make the "shift gate." (You can see two shift gates in your picture). Think of it like a railroad switch that allows a train to switch from one track to another.

Back in the day when there weren't shift gates, you had to soft-pedal (no or very little force on the pedal) from the time you started the shift until the shift was completed. It sounds like a pain, but it really wasn't. With practice, you could do very fast shifts even with the required soft-pedaling. The key was perfect timing.
 

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I was sure it was fine. I just wanted to post that for the OP to see it was norm. I didn't give it a second thought until seeing this post. Figured since it was still in the box I'd take it out and take a pic.
 

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Discussion Starter · #16 ·
Thanks Guys I stopped By the Bike shop today !! And Ummmm yea they all look like that!!
Yea im not used to looking at these new bikes !!
When I got the bike I didnt even no what a presta valve is!!!
 
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