New: Take part in the January 2020 BikeRide Giveaway for a HEDKAYSE | ONE bike helmet

Welcome guest! Register or sign in to participate in the cycling discussions.


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, 11:01 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...
Thread Author Replies Views Last Post
  Help with rear derailleur? BSciacca 2 729 08-28-2019, 02:52 PM
Last Post: CharleyFarley
  Help.. Rear derailleur wrong position? Quixoticish 0 4,739 06-06-2018, 06:56 PM
Last Post: Quixoticish
  SRAM rear derailleur arm length jacke 0 4,891 06-28-2017, 04:52 AM
Last Post: jacke
  Road Bike Rear Derailleur Problem Lighttower 5 7,456 05-19-2017, 01:01 AM
Last Post: Painkiller
  Rear derailleur rolling chain off It's your boy 0 5,891 06-05-2016, 04:36 PM
Last Post: It's your boy
  Replacing old rear derailleur eab 3 12,447 05-14-2015, 09:55 PM
Last Post: DaveM
  What if your new rear Dérailleur nordog 3 5,718 05-08-2015, 12:30 AM
Last Post: nfmisso
  Rear Derailleur Suicide Into Spokes. fribbles 5 9,145 04-25-2015, 05:22 AM
Last Post: nfmisso
  Rear Derailleur.. I have no idea what I'm doing jjc5 4 7,413 04-13-2015, 03:38 PM
Last Post: elmore leonard
  SRAM X9 - Rear Derailleur Pulley - Wobbles columkelly@yahoo.com 2 7,969 03-24-2015, 03:07 AM
Last Post: fredbyte

Forum Jump: