Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Fifty Plus (50+) Share the victories, challenges, successes and special concerns of bicyclists 50 and older. Especially useful for those entering or reentering bicycling.

Reply
 
Thread Tools Search this Thread
Old 12-04-07, 04:04 PM   #1
steve91562
Member
Thread Starter
 
Join Date: Oct 2007
Bikes:
Posts: 31
What's the effective top tube?

I'm looking at this bike with the following specs: 57 cm center to top; 72 seat tube angle; 72.5 head tube angle and a 57 cm top tube. I'm trying to figure out what would be the effective top tube with the bike properly adjusted. Assume a 76.5 cm saddle height and bars 2cm higher then the saddle. Can this be figured out w/o a measuring tape?
steve91562 is offline   Reply With Quote
Old 12-04-07, 04:05 PM   #2
steve91562
Member
Thread Starter
 
Join Date: Oct 2007
Bikes:
Posts: 31
The frame size is actually 58 cm center to top.
steve91562 is offline   Reply With Quote
Old 12-04-07, 05:04 PM   #3
stapfam
Time for a change.
 
stapfam's Avatar
 
Join Date: Jan 2004
Location: 6 miles inland from the coast of Sussex, in the South East of England
Bikes: Dale MT2000. Bianchi FS920 Kona Explosif. Giant TCR C. Boreas Ignis. Pinarello Fp Uno.
Posts: 19,915
Why get technical. Measurements don't work because of so many factors. If it has a 58cm top tube- then it has a 58 cm top tube. By raising the saddle and bars by 2 or 4 cms- you can then adjust the seat or bar stem length to suit. You could be putting the seat as much as 7 cms further back- or further forward, and the same on the length of bar stem you fit. That can alter by 10cms if you wish it to.

So in reply to your question the only way -Unless you know where the saddle and bars are going to finish up in the fore and aft position- is to set the bike up and measure- but the top tube will still be 58cms.

Unless you get onto the bike guru on this forum and he disagrees- But I am certain that DG will come up with the same reply.
__________________
How long was I in the army? Five foot seven.


Spike Milligan
stapfam is offline   Reply With Quote
Old 12-04-07, 05:09 PM   #4
BluesDawg
just keep riding
 
BluesDawg's Avatar
 
Join Date: Feb 2005
Location: Milledgeville, Georgia
Bikes: 2015 Specialized AWOL Comp frameset (custom build), 2015 Zukas custom road, 2014 Specialized Crave Pro 29, 2003 KHS Milano Tandem, 1986 Nishiki Cadence rigid MTB, 1980ish Fuji S-12S
Posts: 13,191
Effective top tube does not vary with saddle or handlebar height. On a bike with a level top tube (the way nature intended them to be), the effective top tube length is the top tube length. If the top tube slopes to the rear, the effective top tube length is the level measurement from the center of the head tube to the center of the seat post at the point where the top tube should intersect the seat tube.
BluesDawg is offline   Reply With Quote
Old 12-04-07, 05:12 PM   #5
maddmaxx 
Small Member
 
maddmaxx's Avatar
 
Join Date: Nov 2003
Bikes: Leader home built hardtail, Diamondback Response
Posts: 7,131
Effective top tube length is a way of comparing sloping top tube bikes to the traditional horizontal top tube. Bike setup has little to do with it.

Measure from the centerline of the head tube in a horizontal direction to the centerline of the seat tube as if the seat tube extended up that far and that is the length of the virtual top tube.
maddmaxx is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 04:35 AM.