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18" or 20"

2K views 3 replies 2 participants last post by  empre 
#1 · (Edited)
180cm, 75kg, 83,5cm inseam. 0,226 x inseam gives 18,871.

The dimensions of my old 26" 19" MTB I currently ride:

Top tube length (horizontal): 565mm
Top tube length (actual): 555mm
Seat tube length: 480mm
Head tube length: 140mm
Stem length: 130mm
Wheelbase: 1050mm

170mm of the seatpost tube showing. Click here to see seat position.

Bike I'm interested in: RADON ZR Race 8.0

Dimensions for 18" model (comparison vs my bike in parentheses):

Top tube length (horizontal): 594mm (+29mm)
Top tube length (actual): 569mm (+14mm)*
Seat tube length: 460mm (-20mm)
Head tube length: 115mm (-25mm)
Stem length: 100mm (-30mm)
Wheelbase: 1084,6mm (+34,6mm)

Dimensions for 20" model (comparison vs my bike in parentheses):

Top tube length (horizontal): 612mm (+47mm)
Top tube length (actual): 588mm (+33mm)*
Seat tube length: 505mm (+25mm)
Head tube length: 130mm (-10mm)
Stem length: 100mm (-30mm)
Wheelbase: 1103,7mm (+53,7mm)

* the site doesn't display this, it's just my "approximate" calculation.

As you can see. Both bikes are longer than my 19", but the 18" is a bit lower and the 20" is a bit higher.

If I want to get same distance from seat to the handlebar that I have in my current bike (which I like), it would mean that I must use 100mm stem on the 18" model and 80mm stem on the 20" model.

The seatpost tube would be showing 190-200mm with the 18" model and 145-155mm with the 20" model. Not sure how much is considered "too much" in general.

When I get the bike I will change the tires from 57mm to something around 40mm and I will also change the suspension fork to rigid one because I ride more in the urban areas and roads with harder surfaces. Even though I ride mostly on easy flats (fitness, urban exploring, national parks, touring) I will get MTB because a) I like the driving position b) I drive year-round (nordic winter) c) it gives me the most freedom and it's nice that I can drive basicly where ever I wan't without any worries.

Which one do you suggest and why? :)
 
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#2 ·

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#3 ·
Thanks for noticing my calculation mistake! I used the actual top tube length with my own bike dimensions for some reason. Corrected the first post.

Ok now it seems that 18" would be the better options since I think 100mm stem would be a lot better for my driving purposes than 80mm. Even more so since I currently ride with 130mm and it feels good too.

Will check more about that Canyon tomorrow. Thanks for the suggestions.
 
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