Go Back  Bike Forums > Bike Forums > Fitting Your Bike
Reload this Page >

Road Frame Size

Notices
Fitting Your Bike Are you confused about how you should fit a bike to your particular body dimensions? Have you been reading, found the terms Merxx or French Fit, and don’t know what you need? Every style of riding is different- in how you fit the bike to you, and the sizing of the bike itself. It’s more than just measuring your height, reach and inseam. With the help of Bike Fitting, you’ll be able to find the right fit for your frame size, style of riding, and your particular dimensions. Here ya’ go…..the location for everything fit related.

Road Frame Size

Old 06-29-13, 04:51 PM
  #1  
Senior Member
Thread Starter
 
Join Date: May 2013
Location: Westminster, CO
Posts: 186

Bikes: 2016 Hong Fu Gravel Bike, 2015 Motobecane Turino Team

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Road Frame Size

I started cycling again 2 months ago after a 6 year hiatus. I put 2600 miles on my 58 cm road bike back then and never thought anything of the fit. When I started up again, I realized just how stretched out my upper body was, so I swapped my 110 mm stem for an 80 mm version. That has made a big difference, but I don't think I'm satisfied yet with the fit. I am 5'10". I'm thinking about swapping my traditional geometry road frame with a 54 cm semi-compact frame. My current TT length is 57.1 cm. The frame I'm looking at has identical head and seat tube angles with an effective TT length of 55 cm. The only other difference is the BB is 1.2 cm higher on the new frame than my current one.

Do you think this is a worthwhile venture? I don't think I want to reduce the stem length any more. Would I notice the higher BB and corresponding higher center of gravity? Thanks!

Alan
RFEngineer is offline  
Old 06-29-13, 05:36 PM
  #2  
Senior Member
 
Road Fan's Avatar
 
Join Date: Apr 2005
Location: Ann Arbor, MI
Posts: 16,866

Bikes: 1980 Masi, 1984 Mondonico, 1984 Trek 610, 1980 Woodrup Giro, 2005 Mondonico Futura Leggera ELOS, 1967 PX10E, 1971 Peugeot UO-8

Mentioned: 49 Post(s)
Tagged: 0 Thread(s)
Quoted: 1854 Post(s)
Liked 660 Times in 503 Posts
Higher BB/higher CG is a bit of a religious issue. Personally I think I like the feel of a lower BB, 7.5 to 8 cm drop. But one of my best bikes ever, a 1980 Woodrup, had a 6.5 cm drop. It seemed a little toppley when I rode it, but it worked well on a long tour.

A 3 cm reduction in reach is rather drastic. Are you sure you didn't back up too far? Considering this your idea to just buy an arbitrarily shorter frame is a shot in the dark. Is there any way you can try out a friend's bike first?

Another consideration in shortening the TT is toe overlap. On your current bike, how far are you from toe overlapping the front wheel? It'll rarely happen at speed but it could happen at low speed when the bike is less stable. If you are not practiced in how to react, you may go down.

Then again, some people are never bothered if the toe interferes with the front wheel.

Ultimately, the requirement for frame sizing is that it must enable proper bicycle fitting - the actual placement of the contact points. It's preferred to have the correct fitting locations not at the extremes of the positions for bars and saddle that can be achieved with a given frame. I'd say that if you have confidence that these conditions are met with your new frame and cannot be met with your old frame, then go for the new one and see what happens.

Last edited by Road Fan; 06-29-13 at 06:23 PM.
Road Fan is offline  
Old 06-29-13, 07:42 PM
  #3  
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,598

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,355 Times in 862 Posts
center of gravity can be improved with more setback.. distance rearward from plumb line thru the BB axis ..

may be a seat post change, saddle adjustment on the seatpost or a frameset with a lower angle seat tube.
fietsbob is offline  
Old 06-29-13, 07:47 PM
  #4  
Senior Member
Thread Starter
 
Join Date: May 2013
Location: Westminster, CO
Posts: 186

Bikes: 2016 Hong Fu Gravel Bike, 2015 Motobecane Turino Team

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks. The reason this came up was that I actually rode a smaller bike 56cm bike for a short while when I started back up. It was actually very comfortable for me so when I switched back to my normal bike it felt huge. I measured the reach between the two and it was different by about 2 inches! So my 30 cm change was actually less than I tried out between the two bikes.

I'll have to pay attention to toe overlap and see how close I am to that being a problem.
Alan
RFEngineer is offline  
Old 06-29-13, 07:48 PM
  #5  
Senior Member
Thread Starter
 
Join Date: May 2013
Location: Westminster, CO
Posts: 186

Bikes: 2016 Hong Fu Gravel Bike, 2015 Motobecane Turino Team

Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 78 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by fietsbob
center of gravity can be improved with more setback.. distance rearward from plumb line thru the BB axis ..

may be a seat post change, saddle adjustment on the seatpost or a frameset with a lower angle seat tube.
My saddle has been pushed up as far as it will go. I never fitted the bike according to my knees and pedal spindles. I would assume my saddle ended up that far forward due to a reach problem.
RFEngineer is offline  
Old 06-29-13, 07:57 PM
  #6  
Banned
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Posts: 43,598

Bikes: 8

Mentioned: 197 Post(s)
Tagged: 0 Thread(s)
Quoted: 7607 Post(s)
Liked 1,355 Times in 862 Posts
Well a shorter than standard top tube length gets you out of the off the shelf bike frames .
ready for a made to measure custom?
fietsbob is offline  
Old 06-30-13, 07:36 AM
  #7  
Thread Killer
 
Join Date: Aug 2008
Location: Ann Arbor, MI
Posts: 12,428

Bikes: 15 Kinesis Racelight 4S, 76 Motebecane Gran Jubilée, 17 Dedacciai Gladiatore2, 12 Breezer Venturi, 09 Dahon Mariner, 12 Mercier Nano, 95 DeKerf Team SL, 19 Tern Rally, 21 Breezer Doppler Cafe+, 19 T-Lab X3, 91 Serotta CII, 23 3T Strada

Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 3129 Post(s)
Liked 1,696 Times in 1,026 Posts
My opinion, based on what you've said, is that probably the 54cm frame will work well. Road Fan's points are right on, and given your seat is slammed all the way forward on the 58cm, and that the 80mm stem is still a bit off feeling, I think dropping down to a 550TT from a 571TT/80 stem combo will work better, my guess with a 110mm stem. The reason being that the shorter wheelbase will put you further back over the BB and make the bike feel more centered, which I think is what Fietsbob was getting at.

i share Road Fan's uncertanty, but it does sound like most of your height is in your legs, so I say go for it! I'm of the opinion that's it's more difficult to fit and more unpleasant to ride a too big frame than a too little one. Also, the semi-compact frame should have a moderate height head tube, so that you'll be able to dial in the right amount of bar drop.
chaadster is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Clumsy Climber
Fitting Your Bike
3
06-24-13 10:25 AM
velikigrizli
Cyclocross and Gravelbiking (Recreational)
9
12-31-12 08:38 AM
bus_ter
Road Cycling
11
06-08-11 02:18 PM
MagicJade
Long Distance Competition/Ultracycling, Randonneuring and Endurance Cycling
13
05-12-11 03:40 PM
1nsane
Road Cycling
8
05-04-10 07:19 AM

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.