# Bike Geometry Comparison Question



## Barnsie (Jun 8, 2007)

Hello.

I currently ride a 60cm 2006 Trek Madone 5.2 SL, and I'm looking at buying a bike online that is a 59cm Bianchi 928SL. Without riding it, I only have specs to go on for comparison.

I'm attaching the geometry specs for both bikes. Do you think I'll be OK on the new Bianchi? I'm 6'3" / 170lbs and have a 35" inseam if that helps. I feel like I'm not setup in a very aggressive way on my Trek, so perhaps the Bianchi setup could have a higher seat/lower bars setup. The Trek is a standard geometry, while the Bianchi is compact.

Trek:

View attachment 169823


Bianchi:

View attachment 169824


Just looking for a few more opinions before I pull the trigger on anything. Not a LOT of difference in the top tube length, but there is a big difference in the seat tube length (if I'm comparing correctly: actual seat tube length from Bianchi to the Trek's only listed seat tube length), which makes me think my saddle might need to be so high as to be...uh...not good? 

Thanks for the help!


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## pdh777 (Oct 7, 2005)

Define what it is you want to change about the Trek, reach, bike feels too long, nervous front end steering etc..., That being said, the Bianchi will have a slightly higher seat and lower bars just based on measurements.

It may however ride very different from the Trek - based on numerous factors. I would strongly suggest you try finding one to test ride before taking the online plunge.

If you do decide to go for it:

Pay attention to the effective top tube length - seat tube length is very secondary.
If your upper torso is well dialed in on the Trek than that TT length is probabaly a good fit. FInd something close with the Bianchi - you can compensate with a slightly longer / shorter stem to compensate for any minor differences in length.

From the info given the TT on the Trek is 58.2 - add to this the length of your stem

The Bianchi looks to be 57.5 (EFF TT is not designated on your diagram) find the right stem length based on what you need and would like to change on the Trek. You have 7mm diferrence between the two. Most stems are in 10mm incerements (1 cm) so you will either be 7mm shorter with the same stem or 3mm longer with the next stem length up.

Decide what is best for you - Good Luck!


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## PJ352 (Dec 5, 2007)

From what you've offered, I'd have two concerns - HT length and ST length. All you have to do to answer the ST length question is mark the post where it enters the ST on your Trek. Remove the post and measure from the mark to the minimum insertion mark. If it's 4 cm's or less you're taking a chance on the Bianchi, because the ST length is 4 cm's _shorter_ than the Trek's, so that much more post will be exposed.

The HT differences are a litle trickier, but we know the Bianchi's HT length is 2cm's longer than the Trek's, so (roughly) you'll need to remove the equivalent in spacers or lower your stem by 8 degrees to _equalize_ bar height. Going lower would obviously require more changes, but I wouldn't do that until I dialed in the fit on the Bianchi.


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## PJ352 (Dec 5, 2007)

pdh777 said:


> Define what it is you want to change about the Trek, reach, bike feels too long, nervous front end steering etc..., That being said, *the Bianchi will have a slightly higher seat and lower bars just based on measurements.*
> It may however ride very different from the Trek - based on numerous factors. I would strongly suggest you try finding one to test ride before taking the online plunge.
> 
> If you do decide to go for it:
> ...


I disagree with you on the two bolded points. Saddle height is a constant, but the HT length on the Bianchi is 2 cm _taller _than the Trek, so all else being equal, the bars will be _higher_ on the Bianchi.

While I normally agree that on compact frames the effective TT takes precedence over ST length, in this case because the OP is going from a traditional geo to compact _and_ may be at the limit on post travel, ST length is of equal importance.

Good points on the handling characteristics of the Bianchi and test rides. And finding the bike and getting sized/ fitted would answer those questions as well. I looked through the geo chart on Bianchi's website but they don't offer specs on offset/ trail, so even making a comparison 'on paper' is near impossible.

FWIW the effective TT on the Bianchi is 575mm.


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