What kind of stem do i need to get into my preferred position?

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chris47
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by chris47

Am am currently riding an avanti corsa dr with a slammed 100mm -6 degree stem. It has a 12cm headtube.
I can get a very good price on a giant propel in a size medium. The problem is that the headtube is 3cm taller, thus the question goes;
What kind of stem(angle specifically) do i need to get into my current position?
Thanks in advance :D

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prendrefeu
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by prendrefeu

Run the numbers and you'll have an answer.
http://bb2stem.blogspot.com/

Download the spreadsheet enter in known data and see what you get for comparison of position.
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fa63
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by fa63

I will need to crunch the numbers later, but probably -30 degrees, maybe more.

nlouthan
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by nlouthan

You'll need to know the stack and reach measurements for both frames in order to figure this out. The HT length alone does not provide enough information to calculate what stem you'll need.

cyclenutnz
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by cyclenutnz

I've assumed a 15mm headset cover for slammed, it would pay to measure that
For the Propel you'd need to get a Cobb headset cover to be close. Unless the Avanti has a taller cover than 15mm.
As you can see from the Bar XY numbers - it's possible to get pretty close
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wingguy
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by wingguy

A -25 100mm stem will put you 4mm lower and 2 mm longer - assuming the bearing caps are the same stack.

Then that's assuming it's a basic Propel Advanced with a 1 1/8 steerer. If it's a Pro or SL with 1.25 OD2 then you'll be stuck 30mm higher than the Avanti because low rise stems for those are like rocking horse shit.

chris47
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by chris47

Thank you all for the replies. I had no clue that such a fancy program existed :oops:
Wingguy, could you care to elaborate upon how a low rise stem on a giant overdrive steerer tube are "like rocking horse shit"
I really did not get that. how would it differ from a normal steerer tube+ low rise stem?
Thanks again

wingguy
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by wingguy

Well, one of them is made by lots of companies and is freely available, the other one isn't.

Seriously, if it's OD2 and you need a stem more angled than 8degrees then make sure you can find a stem before you buy the bike, otherwise you could be screwed.

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vejnemojnen
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by vejnemojnen

even with switching to a -17 degree (uno ebay) stem, you won't be as low.

but, there is another possible solution, with classic bend bars (like ritchey neoclassic or deda shallow). With those, hoods will get lower, whereas the drops will remain approx. in the same height.

cyclenutnz
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by cyclenutnz

chris47 wrote:Wingguy, could you care to elaborate upon how a low rise stem on a giant overdrive steerer tube are "like rocking horse shit"


In theory Giant make a 20deg OD2 MTB stem that would work nicely for you.
Like Wingguy said - make sure you know you can get one before you get the bike. Especially if you're in Oz/NZ.
1.25 steerers are a pain for bike fit so your choices are dictated by the stems you can actually get hold of

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wheelsONfire
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by wheelsONfire

Wow, you ask for a 30mm lower version or very close!?

I am not sure if that is even nearly possible?
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mimason
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by mimason

As indicated above you can drop the stack of the Propel bearing cap by replacing it which will help overall and then the option of using classic bars for lower drop position.

Im in the same boat as you but to a lesser degree where my f8 is lower that a TCR SL I am getting for a song. I can only lower the cap stack because it has really nice integrated bars that i plan on keeping

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wpccrunner
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by wpccrunner

Instead of a Medium why not go for a Small and use a longer stem? Medium is clearly the wrong size frame
Small Propel has 19mm lower stack and 9mm shorter reach.
You can do the math to figure out stem length/angle needed.

OP did not mention this, but is a size Medium the only available size you can get at the "very good price"?

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