General Harley Davidson Chat Forum to discuss general Harley Davidson issues, topics, and experiences.
Sponsored by:
Sponsored by:

Why are front single disc brakes opposite rear brakes?

Thread Tools
 
Search this Thread
 
Old Mar 28, 2019 | 12:04 PM
  #1  
Mars47's Avatar
Mars47
Thread Starter
|
Road Captain
Veteran: Army
Joined: Apr 2011
Posts: 507
Likes: 9
From: Grand Rapids, MI
Default Why are front single disc brakes opposite rear brakes?

The topic came up in one of the groups I'm in on facebook - "Why is the rotor on the left side of a single rotor big wheel kits?" It seems the most accepted answer is that it balances the brakes between the front being on the left and the rear being on the right. I refuse to believe this because...well...sportsters. I've heard this discussion before, and once again the most accepted answer is that so it doesn't pull to one side when braking with both brakes.

I was wondering if anyone knew of any equations or any other scientific or mathematical facts to prove or disprove this theory.

Personally, I believe that its to show off the wheel when you're parked, and that since the brake rotor is attached to the wheel thats anchored down on both sides the force applied to a single brake side would be negligible to anything that the rider would feel (if anything at all).
Even thinking about it in terms of a longer object - say a conveyor wheel or Flintstones car - does side thats getting the power move faster than the side that is not?

I'm genuinely curious and this has started up quite a healthy discussion at work (I work with a bunch of engineers) with torque-steer(acceleration is the opposition of braking) being the counter argument, but once again....sportsters.

Any ideas? Any discussion?
 
Reply
Old Mar 28, 2019 | 12:22 PM
  #2  
RHPAW's Avatar
RHPAW
Seasoned HDF Member
Joined: Aug 2007
Posts: 21,708
Likes: 17,550
From: Driftless Area
Default

It's the Coriolus effect.
 
Reply
Old Mar 28, 2019 | 12:40 PM
  #3  
mitchxout's Avatar
mitchxout
Cruiser
Joined: Sep 2015
Posts: 208
Likes: 64
From: Asheville. NC
Default

Originally Posted by Mars47
The topic came up in one of the groups I'm in on facebook - "Why is the rotor on the left side of a single rotor big wheel kits?" It seems the most accepted answer is that it balances the brakes between the front being on the left and the rear being on the right. I refuse to believe this because...well...sportsters. I've heard this discussion before, and once again the most accepted answer is that so it doesn't pull to one side when braking with both brakes.

I was wondering if anyone knew of any equations or any other scientific or mathematical facts to prove or disprove this theory.

Personally, I believe that its to show off the wheel when you're parked, and that since the brake rotor is attached to the wheel thats anchored down on both sides the force applied to a single brake side would be negligible to anything that the rider would feel (if anything at all).
Even thinking about it in terms of a longer object - say a conveyor wheel or Flintstones car - does side thats getting the power move faster than the side that is not?



I'm genuinely curious and this has started up quite a healthy discussion at work (I work with a bunch of engineers) with torque-steer(acceleration is the opposition of braking) being the counter argument, but once again....sportsters.

Any ideas? Any discussion?
.

It's a myth. However there are many reasons a bike could swerve when using the brakes. ,Off the top of my head, loose spokes, broken axle, cracked top clamp, bearings, hub or some such major failure. Otherwise, it's a physically impossibility or manufacturers wouldn't allow single discs. Duals are for heat dissipation.
 

Last edited by mitchxout; Mar 28, 2019 at 12:41 PM.
Reply
Old Mar 28, 2019 | 01:06 PM
  #4  
Cygnusx51's Avatar
Cygnusx51
Ultimate HDF Member
Joined: Oct 2011
Posts: 5,691
Likes: 1,651
From: Olean, NY
Default

How about to just evenly distribute the weight. One rotor and caliper on one side of the bike offsets the weight of the other side.
 
Reply
Old Mar 28, 2019 | 01:20 PM
  #5  
ChopperBill's Avatar
ChopperBill
Seasoned HDF Member
20 Year Member
Liked
Loved
Community Favorite
Joined: Nov 2005
Posts: 5,588
Likes: 4,547
From: USA
Default

Wheels turn in different directions?
 
Reply
Old Mar 28, 2019 | 01:30 PM
  #6  
skratch's Avatar
skratch
Seasoned HDF Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Jan 2007
Posts: 20,616
Likes: 4,440
From: anacoco, la
Default

i'd go with weight distribution also. with a single disc, it doesn't matter if you have the rotor on the left right or middle, you can't slow down one side any quicker than the other, ergo. no pulling.
 
Reply
Old Mar 28, 2019 | 03:08 PM
  #7  
Tom84FXST's Avatar
Tom84FXST
Seasoned HDF Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Nov 2009
Posts: 15,705
Likes: 22,718
From: Farmington ,MS
Default

Fx springers have them both on the same side with no ill effects
 
Reply
Old Mar 28, 2019 | 03:14 PM
  #8  
Kawickrice's Avatar
Kawickrice
Grand HDF Member
10 Year Member
Liked
Loved
Community Favorite
Joined: Jul 2013
Posts: 4,752
Likes: 3,271
From: West Central Florida
Default

I had an RD400 back in the day with both disks on the right side, I am of the opinion that it pulled to that side during very spirited braking.
 
Reply
HD Forum Stories

The Best of Harley-Davidson for Lifelong Riders

story-0

7 Surprising Harley-Davidson Products that Are Not Motorcycles

 Verdad Gallardo
story-1

8 Best Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-2

10 Worst Harley-Davidson Motorcycles Ever

 Pouria Savadkouei
story-3

Killer Custom's Jail Break Is The Breakout That Refused to Blend In

 Verdad Gallardo
story-4

Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

 Verdad Gallardo
story-5

Harley-Davidson Reveals Super Cool Cafe Racer Concept

 Verdad Gallardo
story-6

Engraved Rebellion: Inside Bundnerbike's Glam Rock II

 Verdad Gallardo
story-7

10 Motorcycles You Should Never Buy

 Joe Kucinski
story-8

10 Things Harley-Davidson Needs to Fix in 2026

 Verdad Gallardo
story-9

Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider

 Verdad Gallardo
Old Mar 28, 2019 | 04:11 PM
  #9  
Mattbastard's Avatar
Mattbastard
Grand HDF Member
Veteran: Air Force
15 Year Member
Liked
Top Answer: 3
Joined: Nov 2009
Posts: 4,315
Likes: 1,663
From: Tampa
Default

The same reason most bikes pull a little bit to the right, because the throttle is on the right side.



Does nobody understand physics now a days?
 
Reply
Old Mar 28, 2019 | 05:16 PM
  #10  
skratch's Avatar
skratch
Seasoned HDF Member
15 Year Member
Liked
Loved
Community Favorite
Joined: Jan 2007
Posts: 20,616
Likes: 4,440
From: anacoco, la
Default

Originally Posted by Kawickrice
I had an RD400 back in the day with both disks on the right side, I am of the opinion that it pulled to that side during very spirited braking.
completely impossible. it could be that maybe your rear end was starting to slide around having lost traction?
 
Reply



All times are GMT -5. The time now is 05:58 PM.

story-0
7 Surprising Harley-Davidson Products that Are Not Motorcycles

Slideshow: The bar-and-shield logo shows up on far more than motorcycles, some of the company's most unexpected products have nothing to do with riding.

By Verdad Gallardo | 2026-04-29 16:50:35


VIEW MORE
story-1
8 Best Harley-Davidson Motorcycles Ever

Slideshow: Not every Harley gets it right, but these are the ones that genuinely earned their reputation.

By Pouria Savadkouei | 2026-04-15 14:23:21


VIEW MORE
story-2
10 Worst Harley-Davidson Motorcycles Ever

Slideshow: From the troubled AMF years to modern misfires, these bikes earned reputations for reliability issues, questionable engineering, or disappointing performance.

By Pouria Savadkouei | 2026-04-01 20:01:09


VIEW MORE
story-3
Killer Custom's Jail Break Is The Breakout That Refused to Blend In

Slideshow: Killer Custom's "Jail Breaker" build focuses more on stance and visual aggression than mechanical overhaul.

By Verdad Gallardo | 2026-03-18 19:20:32


VIEW MORE
story-4
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?

Slideshow: The Swiss custom shop has taken a Harley Softail and stretched it into something so long and low that it looks closer to a rolling sculpture than a conventional motorcycle.

By Verdad Gallardo | 2026-03-07 16:15:30


VIEW MORE
story-5
Harley-Davidson Reveals Super Cool Cafe Racer Concept

Slideshow: Harley-Davidson's new RMCR concept revives the café racer formula with modern hardware-and it may be exactly the reset the company needs.

By Verdad Gallardo | 2026-03-04 12:23:37


VIEW MORE
story-6
Engraved Rebellion: Inside Bundnerbike's Glam Rock II

Slideshow: A standard cruiser becomes an intricate metal canvas in the hands of a Swiss custom house known for pushing Harley-Davidson platforms far beyond their factory brief.

By Verdad Gallardo | 2026-02-24 18:19:44


VIEW MORE
story-7
10 Motorcycles You Should Never Buy

Slideshow: There is no shortage of great motorcycles to buy, but we would avoid these ten.

By Joe Kucinski | 2026-02-19 14:50:51


VIEW MORE
story-8
10 Things Harley-Davidson Needs to Fix in 2026

Slideshow: Harley-Davidson's challenges aren't abstract; they show up in dropping shipments, shrinking dealer traffic, and strategic decisions that aren't yet translating into growth.

By Verdad Gallardo | 2026-01-13 18:33:17


VIEW MORE
story-9
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider

Slideshow: Graeme Billington's left-hand-drive Shovelhead is as much about problem-solving as it is about classic Harley form.

By Verdad Gallardo | 2025-12-30 11:27:08


VIEW MORE