Originally Posted by
Iride01
I used to ride very large frames for my 5'11" size and not being able to get lower on the bike was one of the motivations for me getting a 56cm over a 58cm Tarmac. I was coming from a '91 Parmount with a 60cm frame.
I've not looked at the geometry numbers close enough, but with the 58cm Tarmac, I don't think I would have been able to get as low as I am now on the 56 cm bike with over half the spacers removed. This was a 2020 bike also, Specialized may have changed sizing methods with the 2021's.
Another thing to think about is crank lengths. Seems that on Tarmacs, those are where they go from 172.5 to 175 mm cranks. So that might be a consideration if you prefer one length crank over the other.
It was for me. I had the 172.5 crank removed and put in 165 mm cranks. With either frame, I would have done that anyway. But if you find not enough difference in stack for you between what ever you finally decide on, then look to be sure to note the size of the cranks and other stuff and figure those in with your frame bigger or smaller decision.
Thank you. Frankly crank size is something I’ve never thought about changing but I’ll def put that into my list of things to consider.
Originally Posted by
melikebikey35
Keep in mind that the stack measurement listed for the new SL7 is WITHOUT the top bearing cover (which you have to use), so add 10mm to the listed number to get the actual stack.
Then seat tube and head tube angles should not be used to determine the sizing. With ST, you should always have your saddle set to the same position, in relation to the BB, so it should not be used to judge reach (i.e. you can't make up for excessive reach, by simply pushing your saddle forward). It should only be used to judge how much setback will be needed, and if you can achieve the desired setback.
HT angle will affect reach slightly, but only if you need to run a ton of spacers
Based on the stack numbers, I'd say go for the 58. But, you also have to consider the wheelbase, front center, and trail numbers as those will have a big impact on the handling/stability of the bike...and vary quite a bite between the two sizes.
So, a 61 with a -12 may actually be the best route for you.
Thank you too. This is super interesting. I remember seeing the spacer discussion in another thread but totally forgot about it when I was typing the post. I’ll update my spreadsheet.