Bicycle Mechanics - Shimano Altus Shifters
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04-30-07, 07:38 PM
I'm not sure if this query is best served by this group, Classic & Vintage, or Mountain Bikes, but as it's technical in nature I figured I'd start it here.
The situation: I'm in the middle of refurbishing an old Bianchi Nyala mountain bike. Shifting is Shimano Altus C10's, and it's using the ST-CT15 shifters (3 x 7). At present, the bike's about 75% reassembled, and I'm down to cleaning and resetting the dérailleurs and shifters. Messing with the shifters before I disassembled the bike (when I got the bike the chain was completely rusted, there was no way I was going to try the drivetrain under normal operating conditions), they climbed the gears step by step very nicely, but when I pulled the lever to reverse the action, it shot to the small sprocket immdiately.
Is this normal action, are the shifters broken, or am I missing something? I'll admit to very little experience with MTB's, having only had a Trek 930 (nothing odd about that indexing) and my current Raleigh Seneca (no indexing) and Schwinn Ranger (SRAM twist grip) to fall back on.
Any advice would be greatly appreciated.
It seems as if the cable tension adjustment is screwed up somehow. Either you have to much cable friction which means you have to check the wire housing for damage or dirt, the wire itself could be damaged, dirty or rusty. Try lubricating the housing, this is the easiest thing to try first. You might also have too high of inner wire tension so just adjusting the barrel in could relieve that symptom.
Did you change the inner wire for the shift control? You may have gotten the wrong wire and thus not compatiable with your unit. Did you change the shift control itself, or the derailleur, or the cogset? If you got the wrong stuff you could be running into a campatibility issues with these too.
If you haven't replaced any of the above mentioned stuff then probably the system is just dirty and you need to clean the chain, cogs, the derailleur and the inside of the shift control then relube everything including the derailleur piviots with a dry lube like Finish Line Teflon Dry Plus.
If the cleaning doesn't take care of it and you didn't replace any components then maybe you have wear on the chain or the derailleur guide pulley or the derailleur pivot.
04-30-07, 08:27 PM
Hmmn, thanks for some good leads. To go in somewhat finer detail: The first test of the shifters were done on the bike prior to disassembly, but after the removal of the rusted chain. I've done some further checking once I took the bike down to component parts, by putting tension on the cable and trying the shifter (about the same technique I use on road bike brifters to set them up for the small sprocket prior to installation). Same result either way: Seven (or three) steps up, one snap down.
Will try the cleaning/lubrication bit once I get to work tomorrow (I work in a Honda motorcycle shop) and see what happens.
By the way, are these things disassembleable by mortal man, or, like brifters, are they throwaways once serious disassembly is considered?
05-01-07, 02:21 AM
Flush out the mechanism with some solvent. Gunk can keep the pawl from engaging quickly enough.
If that shifter has 2 levers, hold the upshift lever and try to SLOWLY "ease it" down a gear at a time. That seems to help get the gunk out of the crevices.
Not that the shifters are necessarily to blame, but you can replace the Altus shifters with Alivios for $30. Do a search on "altus". I posted the link a couple days ago.
05-01-07, 03:27 PM
As a backup, I picked up a set of NOS Altus shifters on eBay for something like $12.00, including shipping, but I'd still like to get the old ones working - if for the learning experience, at least.
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