Retrobike Forum Index

It is currently Tue Nov 12, 2019 11:56 am

* Login   * Register * Search  * FAQ



Post new topic Reply to topic  [ 13 posts ]  Go to page 1, 2  Next
Author Message
PostPosted: Mon Sep 09, 2019 1:05 pm 
Old School Hero
User avatar

Joined: Tue Jun 24, 2014 1:13 pm
Posts: 217
Location: London
Hi guys,

I recently (6 months ago :roll: ) replaced the shifters on my Bear Valley with these Shimano:

Image

The number of speed is the same, 7, and so is the brand, Shimano. But for some reason I can't for the life of me find the correct alignment that makes shifting accurate.
It works OK on the way up (i.e. from small to big cog) but it misses the central cogs on the way down. So, for example to go from speed 4 to 5, I need to skip to 6 and the go up to 5.
Doable, but annoying, especially because it was supposed to be an upgrade :lol:

Is it possible the indexing is different?

P.S. I'm having problems only with the right hand side shifter, not the one in the foreground in the picture (confusing picture, I know, but it's the only one I have)

Cheers


Top
 Profile  
 
 Post subject: Re:
PostPosted: Mon Sep 09, 2019 1:14 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider

Joined: Thu May 06, 2010 10:05 pm
Posts: 9056
Location: Scotland
If it’s ok shifting up the cassette ie to the larger cogs, but not great shifting down then that to me suggests either a sticky cable or a weak/worn out spring in the rear mech. (Shifting up you’re using your force from the shift lever to move the mech, shifting down your relying on the spring in the mech doing the work).

I’d check the rear mech cable first though, a bit too much friction or drag could stop the rear mech doing its job properly, try lubing the cable, making sure the ends of the outer are cut cleanly, that this cable hasn’t rusted inside the outer, and that the cable run has nice smooth curves with no sharp angles or unnecessarily long loops of outer cable.


Top
 Profile  
 
PostPosted: Mon Sep 09, 2019 2:30 pm 
Old School Hero
User avatar

Joined: Tue Jun 24, 2014 1:13 pm
Posts: 217
Location: London
I had thought the same, that the mech was dirty (which it was) and it prevented from shifting down properly.
I cleaned it and nothing changed, but it didn't occur to me to check the cable!


Top
 Profile  
 
PostPosted: Mon Sep 09, 2019 9:40 pm 
Retro Guru
User avatar

Joined: Fri Jun 06, 2014 8:07 pm
Posts: 570
Location: Tunbridge Wells
Could be the grease in the shift mechanism. The stuff Shimano uses dries out over time and gets properly claggy. So, strip the shifter and clean with some degreaser or something like GT85. Regrease with something nice and light — stuff for forks like Pace RC7 or Judy Butter (non retro alternatives probably exist!) work well in my experience. Rebuild, and off you go!


Top
 Profile  
 
 Post subject: Re:
PostPosted: Tue Sep 10, 2019 6:59 am 
Dirt Disciple

Joined: Sun Aug 19, 2012 5:58 pm
Posts: 40
Location: Finland
Sometimes the cable outers can also be worn on the inside, so if the cable doesn't move even after lubrication you could try changing them. Also a misaligned rear mech hanger can cause the symptoms you described.

You could also try loosening the b-tension screw a bit, especially with a worn chain it helps to have the mech as close to the cogs as possible

Indexing is the same so that shouldn't be an issue.


Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Sep 11, 2019 7:09 am 
Dirt Disciple

Joined: Fri Oct 12, 2018 6:28 pm
Posts: 80
I had the same problem on a bike build so I got another rear mech out of my collection fitted it and all was good .
Prior to fitting the second mech I had check ed all the cables and chain length.


Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Sep 11, 2019 7:21 am 
Old School Hero
User avatar

Joined: Tue Jun 24, 2014 1:13 pm
Posts: 217
Location: London
Thank you guys for the help. I might have time tonight to give it a look and I will let you know.


Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Sep 11, 2019 8:11 am 
Retro Guru
User avatar

Joined: Thu Feb 07, 2008 10:51 am
Posts: 437
Location: Oslo, Norway
Hi, I used the same shifters on an old bike for years. It was a cheap replacement to get the bike going again after my grip shifters wore out. They were bomb proof, never missed a beat. Just make sure the rear derailleur has good spring tension and that the cables run smooth.
These might be cheapies, but they work great and for a long time. If they become a little rough, you can remove the plastic caps on top (undo the 2 little screws) and put a bit of grease in there.
Good luck.


Top
 Profile  
 
 Post subject: Re:
PostPosted: Wed Sep 11, 2019 6:46 pm 
Retro Guru
User avatar

Joined: Tue Mar 23, 2010 7:06 pm
Posts: 433
Location: Seattle, WA
Might want to check derailleur hanger alignment. If it's off, you'll always have issues.


Top
 Profile  
 
PostPosted: Wed Sep 11, 2019 8:34 pm 
Old School Hero
User avatar

Joined: Tue Jun 24, 2014 1:13 pm
Posts: 217
Location: London
I think I need to check how to correctly put together a rear derailleur first. I think I made some mistakes when I switched the shifters and now it's in a weird position.
I only noticed it today. When in the highest gear the derailleur is so folded up into itself that the two jockey wheels are horizontal and the chain rubs on itself.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 13 posts ]  Go to page 1, 2  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: stefanolo and 16 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  

About Us

Follow Retrobike

Other cool stuff

All content © 2005-2015 Retrobike unless otherwise stated.
Cookies Policy.
bikedeals - the best bike deals in one place
FatCOGS - Fat Chance Owner's Group

Powered by phpBB® Forum Software © phpBB Group