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Need some help with geometry chart

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Need some help with geometry chart

Old 04-23-19, 03:56 PM
  #1  
Ali89
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Need some help with geometry chart

Hello,

I was wondering if you could help me with interpreting a geomety chart.

I currently have the size S of the first and was wondering if it would be possible to setup the M/L of the second to a similar reach.

I have the first setup with a 76.5 saddle height with 6.5cm of setback with a reach of 52. Many thanks for any help. I'm confused in part as the effective top tube length is so different yet the reach appears similar.

Last edited by Ali89; 04-24-19 at 01:51 AM.
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Old 04-24-19, 12:44 AM
  #2  
AnthonyG
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The short answer is that yes, you can setup the medium frame to be very similar to the small frame.
The reach and stack are the important figures that are hard to fudge.

In truth 700c wheeled bikes can only be made down to a 53/54cm size. Smaller than that they just fudge the geometry to make it look right on a spec sheet.
The difference that's confusing you is that the small frame has a steeper seat tube angle that's pushing the saddle forwards towards the handlebars giving a shorter top tube length on paper. If you go to the trouble of maintaining the same saddle setback then they are pretty much identical with the small having a lower stack/head tube length.

The medium frame will have higher handlebar height without adjustment and a good feature is that the medium frame will allow you to experiment with moving the saddle back giving you more saddle setback than present.

EDIT, OK, I was slightly confused and was only comparing the small to the medium of the same design but the principles still hold. The small and mediums are VERY close. In truth you can't build a good small with 700c wheels and they are just a medium that is fudged on way or another to make it look/seem smaller.

Last edited by AnthonyG; 04-24-19 at 07:08 PM.
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Old 04-24-19, 09:10 PM
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The shallower seat tube angle of bike 2 (M/L) increases the effective top tube length of that bike.
If you are currently running a setback seatpost with bike 1 (S) you may want to use a straight post with bike 2 since the shallower seat angle will place you farther forward in relationship to the bottom bracket/pedals.
Note that the stack on bike 2 is 14.4mm higher than bike 1 so your bars will be considerably higher unless you are currently using a stack of shims under your stem.
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Old 04-26-19, 10:24 AM
  #4  
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Big sheet of paper and draw it out full size?
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