Aurora Geometry

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07-02-2010, 09:50 AM
indysteel

Aurora Geometry

Another TEer has inspired my DH and I to do an end-to-end tour of the Katy Trail. We're thinking of September of next year. As you might guess, :rolleyes: the ride is giving us a good excuse to buy touring bikes. We have road bikes that aren't perfectly suited for the packed limestone of the Katy. At least, that's our rationalization!

My DH already has a Jamis, so he''s pretty sold on the 2010 Aurora in blue. I'm also looking at the 47 cm Aurora in green. Zen mentioned in another thread (Catrin's Surly versus Aurora thread) that it has "unique" geometry, but she didn't really elaborate on what makes it unique.

I happily ride a 50 cm Bianchi Eros Donna, which also has somewhat unique geometry. In comparing the two bikes I tend to think they're comparable, so I'm hoping the Aurora work. Ideally, I'll find a shop that has it in stock for me to try, but if not, I'd like to hear anybody else's take on it.

I'd add that I'm a little gun shy to buy a new bike. Last year, I invested a ton of time, money and energy into another frame--a custom Moots--that ultimately didn't work for me. The Moots is pretty similar to the Bianchi except for a shorter top tube and a steeper head tube. On paper, it should work....but it just doesn't. :(

In trying in vain to get the Moots to work for me, I realized a couple things. I need a slacker seat tube than a lot of bikes that are otherwise my size. It appears that most smaller frams have STAs of 74.5 to 75 degrees. They work for me--so long as I have a seatpost with A LOT of set back and even then, I have to push my saddle back nearly all the way. The Aurora has a 74 degree SA, so I'm hopeful in that department.

I also prefer to have a longer top tube than my measurements would otherwise suggest. I tend to think the Moots is just too cramped for me in this regard. The Bianchi's ETT is 515; the Aurora's is 513. Finally, I have a short inseam. The Bianchi's standover is 28.7, and that's about my limit. The Aurora's standover for the 47 cm is less than that, so I should be okay.

If anybody had any thoughts after seeing those numbers, let me know.

Thanks!
07-02-2010, 12:06 PM
Cataboo

I'm 5'1 & really hate a seat tube angle other than about 73 - 73.5 degrees - even then I've got a setback seatpost and the seat most of the way back.

touring bike wise - look at the old trek 520's - the small ones still have 73 degree seat angles. The new ones have like 74 or 75. The REI novara touring bike has a 73 degree seat angle in the small sizes, as does the bikesdirect.com touring bike.

The rawlands sogn frames also have 73 degree seat angles in their small sizes.

I've been on Zen's aurora - it felt fine a little too upright for me how she had it set up, but I didn't pedal it long enough to see how much the 74 degree angle irked me. I don't know how long of a stem she has on it - but I like a longer top tube (520-530)
07-02-2010, 12:12 PM
Zen

Too many numbers make me dizzy and cause my ADD to flare up. No kidding.
07-02-2010, 12:24 PM
indysteel

Quote:

Originally Posted by Zen

Too many numbers make me dizzy and cause my ADD to flare up. No kidding.

Sorry to confound you. :o Just ignore the numbers if you can and explain what you meant in describing the Aurora's geometry as "unique." Thanks!
07-02-2010, 12:27 PM
Cataboo

Quote:

Originally Posted by indysteel

Sorry to confound you. :o Just ignore the numbers if you can and explain what you meant in describing the Aurora's geometry as "unique." Thanks!

I think she just means unique in that it really works for her.
07-02-2010, 12:29 PM
indysteel

Quote:

Originally Posted by Catriona

I'm 5'1 & really hate a seat tube angle other than about 73 - 73.5 degrees - even then I've got a setback seatpost and the seat most of the way back.

touring bike wise - look at the old trek 520's - the small ones still have 73 degree seat angles. The new ones have like 74 or 75. The REI novara touring bike has a 73 degree seat angle in the small sizes, as does the bikesdirect.com touring bike.

The rawlands sogn frames also have 73 degree seat angles in their small sizes.

I've been on Zen's aurora - it felt fine a little too upright for me how she had it set up, but I didn't pedal it long enough to see how much the 74 degree angle irked me. I don't know how long of a stem she has on it - but I like a longer top tube (520-530)

Thanks for the suggestions, but I guess I should clarify that I can get a bike to work that has a steeper STA, so the Aurora's 74.5 STA isn't a problem. It's just a matter of using a seatpost with a fair amount of set back.
07-02-2010, 03:54 PM
wnyrider

Quote:

Originally Posted by indysteel

... I can get a bike to work that has a steeper STA, so the Aurora's 74.5 STA isn't a problem. It's just a matter of using a seatpost with a fair amount of set back.

I just tested out an Aurora on Monday. I am taller than you and he put me on the 53 size with a 73 degree STA. We couldn't dial in my seat without throwing off my leg extension or cockpit reach (his words not mine). The seat had to be raised for my leg length, but then my reach felt too forwards putting more weight on my hands. I thought maybe it exaggerated the lower height of the headtube, making it even lower. He wanted to put on an adjustable stem and use spacers and not use the stem sleeve originally on the bike. I ended up telling him I wanted to think about it first.
Your plan to use a seatpost with a more setback position sounds promising. How does that end up regarding your knee position over the pedals and having push power?