A popular pun is told about unicycles and bicycles (or bicycles and tricycles):
 
Q:What’s the difference between a poorly dressed man on a unicycle and a well-dressed man on a bicycle?
A: Attire. (A tire.)
 
“What’s the difference between a poorly dressed man riding a tricycle and a well dressed man riding a bicycle?” was posted on Twitter on Deember 2, 2008. The joke started to go viral in 2010. “What is the difference between a well dressed man on a bicycle and a badly dressed man on a tricycle? Attire!!” was posted on Twitter on March 6, 2010.
 
     
Twitter
Jennifer
‏@comstockj
What’s the difference between a poorly dressed man riding a tricycle and a well dressed man riding a bicycle?
9:47 PM - 2 Dec 2008
   
Twitter
Colleen Oakley
‏@mytreasurebox
What is the difference between a well dressed man on a bicycle and a badly dressed man on a tricycle? Attire!!
11:34 AM - 6 Mar 2010
 
Twitter
John Pointon
‏@johnpointon
Twitterpun : What is the difference between a well dressed man on a tricycle and a poorly dressed man on a bicycle? A tyre. #pun #humour
10:41 AM - 1 May 2010
 
Twitter
Julie
‏@sun_freespirit
@Ali_Sweeney Q: What’s the difference between a well-dressed man on a tricycle, and a poorly dressed man on a bicycle? A: A tire
9:52 PM - 22 Jun 2010
 
Twitter
Simply Puns!
‏@SimplyPuns
What’s the difference between a well dressed man on a bicycle & a poorly dressed man on a tricycle? Attire #SimplyPuns
6:24 PM - 4 Aug 2011
   
Twitter
Fion
‏@foreverfion
@AmyMcLovin I have a great joke 😊 What’s the difference between a poorly dressed man on a unicycle and a well dressed man on a bicycle?
3:10 PM - 24 Nov 2011
 
BuzzFeed
67 Jokes That Will Make You Go “Ba Dum Tss”
Three men walk into a bar… Ouch!
posted on Apr. 18, 2014, at 3:45 p.m.
Tanner Greenring
(...)
49. What’s the difference between a poorly-dressed man on a unicycle and a well-dressed man on a bicycle? Attire.
 
reddit 
What’s the difference between a well dressed man on a bicycle, and a poorly dressed man on a tricycle?
submitted October 9, 2014 by rekd1
A tire!
 
Google Books
Scooby-Doo’s Laugh-Out-Loud Jokes!
By Michael Dahl
North Mankato, MN: Capstone Young Readers, A Capstone Imprint
2015
Pg. 202:
What is the difference between a well-dressed man on a tricycle and a poorly dressed man on a bicycle?
Attire!
 
Google Books
Git for Teams:
A User-Centered Approach to Creating Efficient Workflows in Git
By Emma Jane Hogbin Westby
Sebastopol, CA: O’Reilly Media, Inc.
2015
Pg. 193:
What’s the difference between a poorly dressed man on a tricycle and a well dressed man on a bicycle?
Attire.
       
reddit
What is the difference between a well dressed man on a unicycle and a poorly dressed man on a bicycle?
submitted September 25, 2015 by austin_976
Attire
 
Beatnikhiway
20 One Liners That Are ACTUALLY Good
ISAAC TAYLOR
on 1 June, 2016 at 3:16 pm
(...)
13. What’s the difference between a well dressed man on a bike and a poorly dressed man on a unicycle?
Attire.