GPC Ride Rating System

Page last updated 2009-02-11

Contents of this page
What to Expect on a Ride?
The Rating System — Overview
Ride Pace — Details
Bears Loop
Terrain Rating — Details
Terrain Rating — Examples
Rationale
Background and History

What to Expect on a Ride?

GPC welcomes all riders. We especially welcome new and guest riders. We prepared these detailed conventions regarding pace and terrain in order to give ride leaders a good idea of how to pace a ride, and riders a good idea of what to expect.

Ride leaders are expected to ride at the published pace. Riders are expected to check the published pace in advance. These and other ride guidelines are stated in more detail on the separate ride guidelines page.

If you don't know which pace is right for you, it is better to err on the conservative side with your choice. Your sustainable pace for 50 miles may be slower than for 20. If you attempt a ride that may be too fast or too far, you should be self-sufficient in case you misjudged — especially on rides T-pace or faster. If you have questions about the pace or terrain of any given ride, contact the ride leader in advance.

The Rating System — Overview

GPC rides are rated using a notation such as 3/LT/35. The three factors are: terrain/pace/distance. The terrain ratings are:

Terrain Description Avg climbing, feet/mile
1 Essentially flat. 10 - 30
2 A few low hills. 30 - 50
3 Moderately hilly. 50 - 70
4 Hilly, a few steep ones. 70 - 90
5 Very hilly, considerable climbing. 90 - 110
! A "!" after the terrain rating number indicates surprisingly hard hills in view of the overall terrain. See details, below.

The pace ratings are:

Pace Description
XL Extra-leisurely: child-friendly pace with many long stops.
L Leisurely: easy pace, frequent stops, good for new riders.
LT     (Intermediate between L and T.)
T Touring: steady pace, fewer stops, for experienced riders.
TM     (Intermediate between T and M.)
M Moderately fast pace: for strong experienced riders.
MB     (Intermediate between M and B.)
B Brisk: very strong riders; tight fast packs and pacelines.

Mileage follows the first two factors. In the example above, 3/LT/35 is a moderately hilly ride at pace between leisurely and touring of distance 35 miles.

The faster-paced rides usually have fewer regroups, further apart, with less time for off-bike socialization during the ride. M-pace and faster rides usually have a fair amount of riding in packs and pacelines. These differences between the pace groups are not required, but are what typically happens. Specifics often depend on the ride leader.

T-pace and faster rides assume that riders are self-sufficient — i.e., can take care of themselves if they make a wrong turn or are unable to maintain the ride's published pace. This particular distinction is explained in the separate rider guidelines, items 3-7.

Over the years, many GPC members have requested detailed quantitative definitions for the pace and terrain ratings. The following sections provide those definitions.

Ride Pace — Details

GPC ride pace is formally defined using average ride speed on a known course of mixed terrain. The specific course is the Bears Loop (also known as the ITT Loop), an 18.7 mile loop with some nearly flat stretches, some rollers, some hills — and a total of about 1600 feet of climbing (average climb about 85 feet/mile). The paces correspond to the following average speeds around the complete loop when ridden under ideal conditions, but not treating it as a race or time trial. The ride times can also be extrapolated to rides of lengths 50 and 100 miles over similar mixed terrain:

Pace Avg mph Ride time,
Bears Loop,
18.7 miles
Ride time,
mixed terrain,
50 miles
Ride time,
mixed terrain,
100 miles
XL 7-9 NA (covers flat terrain and short distances only)
L 8-9 2:20-2:05 6:15-5:33 12:30-11:07
LT 9-10 2:05-1:52 5:33-5:00 11:07-10:00
T 10-12 1:52-1:34 5:00-4:10 10:00-8:20
TM 12-14 1:34-1:20 4:10-3:34 8:20-7:09
M 14-16 1:20-1:10 3:34-3:08 7:09-6:15
MB 16-18 1:10-1:02 3:08-2:47 6:15-5:33
B 18+ 1:02- 2:47- 5:33-

As used here, "average speed" means average ride speed for the entire ride excluding rest stops or regroups, and "ideal conditions" means dry roads, moderate temperatures, no precipitation, and no wind. For different terrain or conditions, the paces correspond to the same amount of effort by the same rider, and may therefore have different average speeds. Flatter rides and flatter stretches will have a higher average; hillier rides will have a slower average.

Bears Loop

If you wish to time yourself in order to find your natural pace, here are riding directions for the Bears Loop. The start point is San Pablo Dam Rd (SPDR) and Bear Creek Rd, approximately 2.5 miles north of Orinda. (It's also the intersection of Wildcat Canyon Rd and Camino Pablo.) North on SPDR; R on Castro Ranch Rd; R on Alhambra Valley Rd; R on Bear Creek Rd; return to origin. The club offers timing and tempo rides around this loop several months each year; see the monthly ride listings or see under ITT heading on the ride series page. The Grizzly Peak Century courses, both metric and full, cover a similar mix of terrain with similar overall average climbing.

Terrain Rating — Details

GPC terrain rating is formally defined using average climbing per mile over the entire route. It is:

Terrain Rating  =  ((Climbing, in feet) / (Distance, in miles)) / 20

generally rounded to the nearest integer. For example, a century ride (100 miles) with 6200 feet of climbing has terrain rating (6200 / 100) / 20 = 62 / 20 = 3.1, which would be called a '3'.

The definition also allows for terrain 0 = astoundingly flat, and terrain 6 or more = enormously hilly.

An exclamation point "!" in the terrain rating means "SURPRISE!". It signifies surprisingly hard hills — long and/or steep — in view of the average. The "!" should be used for routes where the overall average alone might be misleading. An example is the Del Puerto Loop which is usually considered "3" overall. Because it has one notably long hard steep section, it is generally rated "3!". The "!" is relative to the overall terrain rating: The steep stretch on Del Puerto would be no surprise if the terrain were otherwise rated as 5.

Terrain ratings in ride listings are often approximations, for several reasons: The total climbing of some routes is not well known; not all ride leaders have the time or inclination to do detailed altimetric research; and in any case, not all altimeters agree. Even so, with experience, many people are able to make quite good guesses to the nearest integer. If your own altimetric research indicates that the terrain rating for a given route should be refined, feel free to share that knowledge with the ride leader (in a constructive sort of way!) and send it in as an example, as explained in the next section.

Terrain Rating — Examples

Examples of quantitative terrain ratings for common routes can help a lot. A good set of examples can give us all a gut feeling for what the numbers mean, and they will allow ride leaders to keep on rating terrain the way most of us currently do — by instinct. The point of good examples is to give us better instincts and, hence, better ratings.

We have prepared a preliminary set of examples. It is available here, in the form of an Excel spreadsheet. We invite those club members who are interested in quantitative ratings to contribute more examples. Send them to <webminion at grizz dot org>. At a later time, we may move the examples (or some of them) from the spreadsheet into this page for easier reference.

Rationale

As noted above, the reason for these explicit quantitative definitions is to give everybody a better idea of what to expect. To define pace, a specific "benchmark" course was chosen for concreteness, and mixed terrain was chosen, rather than flat, because most GPC rides are over mixed terrain. The Bears Loop was chosen in particular because it is representative terrain, it is familiar to many people in the club, and because the club offers monthly timing rides around it. The purpose of quantitative terrain definitions is so that we all mean the same thing by (for example) the description "moderately hilly" and we can, in principle, all agree to the same rating for any given route.

Background and History

Pace Rating Background. The names Leisurely, Touring, Moderate, Brisk and the terrain/pace/distance scheme date from the misty past of early GPC history. Groundwork for the present definitions was laid at a special club meeting on ride pace held 7 December 1999. The quantitative definitions of ride pace used here were adopted by unanimous vote at the regular club meeting of 19 April 2000; an article about it appeared in the May 2000 Wheel Truth, page 4. The verbal descriptions and other accompanying explanations used here were adopted by unanimous vote at the regular club meeting of 17 January 2001.

Terrain Rating Background. The club historian, Pierre LaPlant, states that ft/mile/20 was the original basis for the numerical terrain rating system (1, 2, 3, 4, 5) when it was devised in 1975. Apparently, however, ft/mile/20 was not formalized; by the 2000 decade only a few members used it or knew about it. It was formally adopted at the regular club meeting of 14 January 2009. The surprise flag "!" was proposed by the Terrain Rating Committee in February 2001 and has been in informal use ever since. It too was formally adopted at the regular club meeting of 14 January 2009.

Further Background Info. Further background info on the terrain proposals is archived on the GPC maillist. To see the following references, you'll need to enter your GPC mailman username and password (they are automatically mailed to GPC maillist users the first of every month).
The Terrain Rating Committee Report, February 2001, considered seven (!) different rating schemes which had been proposed by club members:
http://www.grizz.org/mailman/private/gpc-talk/2001-February/003402.html.
Pierre's statements are here:
http://www.grizz.org/mailman/private/gpc-talk/2001-February/003454.html, http://www.grizz.org/mailman/private/gpc-talk/2001-February/003471.html

This page is maintained by Mark Abrahams, <webminion at grizz dot org>.

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