Under Construction

Choosing a helmet:
Fit is crucial.

Adjustment is important: See: How to Choose a Bike Helmet: Sizing Guide - REI Expert Advice
and Best Bike Helmet Buying Guide - Consumer Reports

MIPS feature:
One newer offering in helmet technology is the Multi-directional Impact Protection System (MIPS). This thin, low-friction liner inside the helmet allows the outer shell to slide a few millimeters across the skull on impact, reducing rotational force and the amount of energy transferred to the head. Rotational force is thought to be a factor in concussions.

In Consumer Reports tests of two pairs of the same brand and model helmets--one MIPS, one not--the MIPS helmets reduced rotational force up to 43 percent compared with the non-MIPs helmets.

Styles:
There are several styles of helmet.
See Bicycle Helmet Types | helmets.org
and Helmets for different cycling disciplines explained | EvansCycles.com, UK

There are other types, childrens, full-face (for dare devels)
Reviews/Ratings:
Helmet Ratings Virginia Tech College of Engineering Tests 2018
They tested 30 helmets with scores from 10.9 (best) to 25.3 (2 stars).
They used the the STAR protocol originally developed for football helments to estimate the incidence of concussion that a college football player may experience.

A lower score offers better protection
Helmet Cost Score
5 star
Bontrager Ballista MIPS $200 10.9
Louis Garneau Raid MIPS $80 12.3
Bell Stratus MIPS $150 12.9
Specialized Chamonix MIPS $75 13.1
4 star
SCOTT Arx PLUS (MIPS) $100 14.3
Bontrager Quantum MIPS $100 14.3
Specialized S-Works Prevail II $225 14.8
Smith Optics Overtake $163 15.0
Bell Draft MIPS $60 15.6

  The Bontrager Ballista is designed for racers with a lot of aerodynamic testing and claim with only 3 vents in front they get better ventilation than their competitors. Of course when you're going 30 MPH only 2 holes would probably give you good ventilation.
see YouTube.

 
 
  
 
 
Louis Garneau Raid MIPS

 
Specialized Chamonix MIPS


Consumer Reports Review 2016 Scores ranged from 88 to 22.
Manufac
turer
Price
CR Rating
MIPS
Impact
absorption
Ventilation
Fit
adjustments
Ease of use
Scott Arx Plus $92 88 * 5 4 5 5
Cannondale CAAD MIPS bike helmet $80 85 * 5 4 3 5
Giro Register MIPS bike helmet $65 85 * 5 5 3 5
Bell Gage Mips bike helmet $195 83 * 5 3 5 5
Bontrager Circuit MIPS bike helmet $150 83 * 5 4 5 5
Giro Register bike helmet $45 83 5 5 3 5
Bell Draft $40 82 5 5 3 5
Bontrager Circuit $80 80 5 4 3 5
CR Rating - Consumer Reports 2016


                  Scott Arx Plus

Links:
Bike Helmet Buying Guide | Consumer Reports
Bicycle Helmet Ratings - Virginia Tech College of Engineering Tests 2018
Bicycle Helmet STAR Protocol
Bicycle Helmet Ratings Overview | Consumer Reports 2016

last updated 3 Oct 2018