Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

The ideal gear changes.

Old 02-15-11, 06:54 PM
  #1  
NYRhyme
Senior Member
Thread Starter
 
Join Date: Oct 2010
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
The ideal gear changes.

I've done a lot of searching for videos about how the "ideal" gear change would look like and most if not all of them only display the rear spokes. What i'm interested in is the two big spokes up front, so if anyone has a link to what an smooth front spoke (not sure of proper term) looks like post here .

Reason I wish to know is because i've been doing a lot of fine tuning and I don't have a reference to what looks ideal. :l At the moment when I go from the smallest cog to the larger cog (mine only has 2 big cranks), The chain will start to be grabbed by the larger one while dragging along the side of the crank, then after grabbing it for a while it'll pop on.

Type of bike is a jamis Ventura comp

any other questions feel free to ask. Thanks
NYRhyme is offline  
Old 02-15-11, 07:11 PM
  #2  
rschleicher
Retro-guy
 
Join Date: Oct 2006
Location: Danville, CA
Posts: 285

Bikes: 1980 Raleigh Super Record

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
I assume that when you say "two big spokes up front" you are really talking about the chain rings on the crank, and by "rear spokes" you are talking about the cassette (the rear cogs)?

In any case, the shift from small chain-ring to large chain-ring is inherently the least-smooth shift, due to the fact that the difference in size and tooth-count between the two chain-rings is so large. This is especially true for a compact double crank (typically with 34-tooth and 50-tooth chain rings. That said, the shift to the larger chain-ring should still take place fairly quickly. Part of the issue is that the front shift lever for some lower-priced groups lacks a trim capability, so the derailleur ends up being more or less directly over the new chain-ring. Whereas if the front shifter has trim capability, it can be set up so that the front derailleur can actually move a little past the ideal position with the shift (leading to a faster/smoother shift), and then be trimmed back a bit.
rschleicher is offline  
Old 02-15-11, 07:23 PM
  #3  
NYRhyme
Senior Member
Thread Starter
 
Join Date: Oct 2010
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
What you've assumed is correct, but I can't picture what you've stated. I haven't actually got on my bike since i've done the fine tuning and at the moment I'm just doing gear switches with the bike upside down.

If there is any video footage please show. >.<
NYRhyme is offline  
Old 02-15-11, 07:54 PM
  #4  
mike_s
Senior Member
 
Join Date: Sep 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Keep in mind that front shifts should not be done while pedaling with any force - only movement. When you shift the rear, the dérailleur is moving the slack part of the chain. When you shift the front, it's moving the part which would be under tension if you're pedaling. On modern gearsets, the front shift is also helped by pins and ramps on the side of the gear, which helps the chain ride up the gear and get onto the teeth. It can take some part of a revolution for the chain to grab on to one of these pins, which can also make front changes slower.

http://www.sheldonbrown.com/gloss_p.html#pins
mike_s is offline  
Old 02-15-11, 08:07 PM
  #5  
NYRhyme
Senior Member
Thread Starter
 
Join Date: Oct 2010
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Thanks guys

I've done some further research and if it's the case when a chain rubs against the sprocket wall that's bad correct? Currently my chain rubs the largest sprocket wall for a short time before being pulled.

Should I loosen tension which is turning clockwise i'm assuming? Or lessen tension which is turning counter clock.

Correct me in case i'm incorrect above, thanks.
NYRhyme is offline  
Old 02-15-11, 08:18 PM
  #6  
mike_s
Senior Member
 
Join Date: Sep 2008
Posts: 202
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by NYRhyme View Post
I've done some further research and if it's the case when a chain rubs against the sprocket wall that's bad correct? Currently my chain rubs the largest sprocket wall for a short time before being pulled.
That's not unusual for a shift to the larger front cog - it can rub until it gets picked up by one of the pins I mentioned.
mike_s is offline  
Old 02-15-11, 08:52 PM
  #7  
NYRhyme
Senior Member
Thread Starter
 
Join Date: Oct 2010
Posts: 68
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by mike_s View Post
That's not unusual for a shift to the larger front cog - it can rub until it gets picked up by one of the pins I mentioned.
If that's the case.....then I guess i just have to test ride my bike.
Thanks a lot.
NYRhyme is offline  
Old 02-15-11, 09:11 PM
  #8  
Al1943
Senior Member
 
Join Date: Feb 2005
Location: Oklahoma
Posts: 9,438

Bikes: Trek 5500, Colnago C-50

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
You should not make adjustments with the bike inverted. Find a way to hang the bike in normal riding position.
Follow the instructions for front derailleur adjustments found at www.parktool.com. Do each step in proper sequence leaving nothing out.
Al1943 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
perrycas
Electric Bikes
9
04-26-13 06:49 AM
LóFarkas
Singlespeed & Fixed Gear
15
10-01-07 12:47 PM
gerv
Living Car Free
47
06-27-07 06:37 PM
krazyderek
Road Cycling
28
09-12-05 03:40 PM
zanq
Road Cycling
0
04-20-05 09:04 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.