Have questions or want to discuss cycling? Join Now or Sign In to participate in the BikeRide community.

New: Take Part in the new April's Giveaway for a Chance to Win the Euybike S4 Pro Max ebike worth $1299


What do these numbers mean for a rear derailleur
#1
Hello again,

Another newbie question that I couldn't find in a search.

Looking at a rear derailleur this time.

What do these numbers mean?

Max Cog: 30
Wrap: 40
Speed 5,6,7

I assume on speed, it's saying on the rear sprockets, it supports 5, 6 or 7 sprockets? That's not the 'speeds' of the bike itself is it?
  Reply
#2
Hi Rastoma. Yes, the 5, 6 or 7 refers to the number of rear cogs. It's not as big a deal as most manufacturers make it out to be BUT - as we gained numbers of rear cogs, chains (and derailleurs) got narrower. Any 5, 6 or 7 should be fine for even up to 8.

The 'max cog' refers to the largest number of teeth on the large cog that the drlr was designed to handle. For example, an 11-30 stack.

Chain Wrap is the capacity that the drlr has for keeping the chain from going slack between extremes. (Large chainring - small chainring) + (large rear cog - small rear cog) = chain wrap capacity.

For what it's worth, (not being condescending, just informing) hardly anyone who is into bikes will use terms like "21 speed" or "28 speed" anymore. They will, of course, know what you mean. A 21 is a 7 spd with a triple up front. A 18 would be a 9 spd with a double.

Welcome to BT!
Rob
Wheelies don't pop themselves. (from a QBP fortune cookie)
  Reply
#3
(11-23-2011, 07:01 PM)RobAR Wrote:  ........
A 18 would be a 9 spd with a double.
........

Or a 3 x 6 Smile

My World Tourist and Sierra Sport are both 2 x 7, and our T50 is currently 3 x 7, and in a month or so will be 3 x 9.
Nigel
  Reply


Possibly Related Threads...

Forum Jump:

[-]
10 Latest Posts
Austin, TX Bike Lane Change
Yesterday 11:51 AM
Tubeless vs. tubes: What are the pros an...
Yesterday 06:41 AM
Do you have a four foot rule?
04-19-2025 02:21 PM
Let me introduce myself
04-19-2025 07:56 AM
Paris-Roubaix
04-18-2025 06:19 PM
What are the best cost effective ways to...
04-18-2025 01:34 PM
Climbing hills: Where have you found the...
04-18-2025 12:27 AM
Schrader vs Presta
04-17-2025 09:59 AM
New To The Forum
04-16-2025 11:50 PM
Good morning form Alberta CA
04-16-2025 08:16 AM

[-]
Join BikeRide on Strava
Feel free to join if you are on Strava: www.strava.com/clubs/bikeridecom

[-]
Top 5 Posters This Month
no avatar 1. GirishH
17 posts
no avatar 2. Flowrider
15 posts
no avatar 3. meamoantonio
13 posts
no avatar 4. SPINMAN
13 posts
no avatar 5. rydabent
9 posts