Go Back  Bike Forums > Bike Forums > Road Cycling
Reload this Page >

shorter stem equals over the bar

Notices
Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

shorter stem equals over the bar

Old 05-25-15, 03:28 AM
  #1  
Senior Member
Thread Starter
 
Join Date: Aug 2012
Posts: 459
Liked 2 Times in 2 Posts
shorter stem equals over-the-bar

As a result of moving my saddle rearward (Steve Hogg's point of balance) and wanting to have a more upright position, I also change my stem length from 110mm (-17) that I've been on for about a year to 80mm (-17) hoping to maybe have a similar reach. But after a couple of days in this new position I had two occasions that I need to pull the front brake really hard and on both occasions my rear wheel lifted way off the ground and almost sent me flew over the bar had I not set my cleat tension to very-loose.

Now I don't remember having to brake real hard during my life with the 110mm stem position, but is shortening your stem contribute to this (physics?) or that I'm not just used to the new position?

edit: move the saddle aft position by about 18mm and didn't alter the saddle-to-drop position (105mm)

Last edited by bleui; 05-25-15 at 03:57 AM.
bleui is offline  
Old 05-25-15, 03:42 AM
  #2  
Senior Member
 
k_kibbler's Avatar
 
Join Date: Aug 2014
Posts: 241

Bikes: Canyon Ultimate CF SL

Likes: 0
Liked 0 Times in 0 Posts
a. Saddle further back = more weight over rear wheel = lower chance of going over the bars

b. More upright position = higher center of gravity = higher chance of going over the bars

Without more details of your old and current position, how much further back, how much more upright, A and B are a wash and either you're not used to hard braking or you're not used to your new position, or both. Stem length alone shouldn't directly affect braking.
k_kibbler is offline  
Old 05-25-15, 05:34 AM
  #3  
Senior Member
 
Join Date: Sep 2011
Location: Quebec, Canada
Posts: 780

Bikes: Argon18 Gallium 2016, Trek Emonda SL6 Pro 2018, Salsa Beargrease

Likes: 0
Liked 0 Times in 0 Posts
Saddle placement should not have impact on heavy breaking since wherever your saddle is, you should shift your weight all the way back to keep maximum control of the bike while braking.

So it's either the center of gravity that is a bit higher, or the driver that is not yet used to his new position?
generalkdi is offline  
Old 05-25-15, 05:46 AM
  #4  
ka maté ka maté ka ora
 
pdedes's Avatar
 
Join Date: Oct 2008
Location: wessex
Posts: 4,423

Bikes: breezer venturi - red novo bosberg - red, pedal force cg1 - red, neuvation f-100 - da, devinci phantom - xt, miele piste - miche/campy, bianchi reparto corse sbx, concorde squadra tsx - da, miele team issue sl - ultegra

Likes: 0
Liked 4 Times in 4 Posts
user error
pdedes is offline  
Old 05-25-15, 07:00 AM
  #5  
Flyin' under the radar
 
RNAV's Avatar
 
Join Date: Jun 2010
Location: O'Fallon, IL
Posts: 830

Bikes: '15 LeMond Washoe custom painted, '06 LeMond Croix de fer custom painted, '18 Specialized Crux

Liked 58 Times in 23 Posts
What you describe shouldn't affect the braking performance.

Spit-balling, though, it's possible your brake cable housing could have had a sharp bend in it (causing increased friction), which could have been alleviated by repositioning the handlebars, resulting in reduced friction. When you apply the same amount of perceived effort, you get more braking action.

Originally Posted by bleui
edit: move the saddle aft position by about 18mm and didn't alter the saddle-to-drop position (105mm)
To clarify, if you're moving your saddle aft, you're also effectively lengthening the saddle-to-BB distance. Steve Hogg even mentions that when you adjust the saddle fore/aft, you have to then readjust the saddle height to compensate for this. Based on what you wrote above, it sounds like you didn't readjust your saddle height (unless you did, and also made a corresponding handlebar height adjustment to keep the same saddle-to-drop position).
RNAV is offline  
Old 05-25-15, 07:03 AM
  #6  
Senior Member
 
wphamilton's Avatar
 
Join Date: Apr 2011
Location: Alpharetta, GA
Posts: 15,279

Bikes: Nashbar Road

Liked 341 Times in 228 Posts
Steve Hoggs makes a lot of sense, except for his notion of setting the seat by crouching balance, and your question relates to why he is wrong. As mentioned earlier you should shift your balance back from the seat during a panic brake. The balance point when braking, when sitting, or when pedaling, is different from the center of gravity while crouching.

A shorter stem does not mechanically make over the bars more likely, except if you change your position and posture as a result of it.
wphamilton is offline  
Old 05-25-15, 07:55 AM
  #7  
Senior Member
 
GravelMN's Avatar
 
Join Date: May 2014
Location: Rural Minnesota
Posts: 1,604
Likes: 0
Liked 2 Times in 2 Posts
Get your butt back and drop your elbows a bit and your chance of going OTB will be greatly reduced. A more upright position can affect braking dynamics, but if you moved both your seat and handlebar positions back with no other changes, this should shift your center of gravity back without raising it substantially, which should reduce rather than increase the chances of rear wheel lift. Front brake modulation is the more important factor here. Maximum braking effect occurs right at the point where both wheels are still rotating and the back wheel is just starting to lift. Once enough weight comes off the back wheel that it locks you lose braking effect from the rear wheel and gain no additional braking force (which begins conversion to the rotational force that could eventually throw you over the bar) from the front.
GravelMN is offline  
Old 05-25-15, 10:24 AM
  #8  
Senior Member
 
Join Date: Dec 2010
Location: Above ground, Walnut Creek, Ca
Posts: 6,682

Bikes: 8 ss bikes, 1 5-speed touring bike

Likes: 0
Liked 4 Times in 4 Posts
standing on the pedals, riding downhill, long stem, light bike, short wheelbase, hard front braking all contribute to a header. not a complete list...
hueyhoolihan is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
johngwheeler
Road Cycling
26
07-29-17 09:14 PM
curttard
Road Cycling
33
07-20-17 08:52 PM
jambon
Fitting Your Bike
2
08-10-16 10:19 AM
workingthrewit
Road Cycling
2
05-15-16 04:43 AM
Bacciagalupe
Fitting Your Bike
4
09-06-14 12:46 PM

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 - Your Privacy Choices -

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