Replacement for lost guide pulley, Shimano STX 7-speed
11-06-21, 06:54 PM
#1
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Replacement for lost guide pulley, Shimano STX 7-speed
I have a 1996 Trek 930 I use with a kid trailer. While towing my son to tennis this week, the upper guide pulley fell off the derailleur, including the bolt. It's a 7-speed Shimano STX. Thoughts on how I should fix this? I found replacement pulleys at my LBS that aren't a perfect match but were cheap enough ($3) to give them a try, but the shop didn't have a bolt long enough to hold it in place. Is it worth searching for a bolt to fix this derailleur with the mismatched pulley, or should I buy a newer (or used but nicer) derailleur? Photo attached of the original pulley (which I found later lying in the street) and the new one from the bike shop.
The bike suddenly started shifting poorly - wouldn't go into the smallest cog - and adjusting the cable tension on the fly with the barrel adjuster at the shifter didn't help. It didn't occur to me to check the derailleur itself (and I was running late, didn't want to stop). I noticed this derailleur has both pulley bolts on the same side which I suspect explains the problem, the upper one spins in the direction that would tend to loosen the bolt. All my other bikes have the upper pulley bolt with the head on the opposite side from the lower one.
The bike suddenly started shifting poorly - wouldn't go into the smallest cog - and adjusting the cable tension on the fly with the barrel adjuster at the shifter didn't help. It didn't occur to me to check the derailleur itself (and I was running late, didn't want to stop). I noticed this derailleur has both pulley bolts on the same side which I suspect explains the problem, the upper one spins in the direction that would tend to loosen the bolt. All my other bikes have the upper pulley bolt with the head on the opposite side from the lower one.
11-06-21, 08:00 PM
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It all depends on whether the STX was running narrow pulleys. 6/7 speed pulleys were wider. When 8 speed came out 10 tooth narrow pulleys were used. Yours looks like a narrow. If you use a wider pulley the attach bolt will be too short.
8 speed narrow 10t pulleys are almost impossible to find. Unless you are running at the max cog or above, you can probably use a set for 9 speed.
John
8 speed narrow 10t pulleys are almost impossible to find. Unless you are running at the max cog or above, you can probably use a set for 9 speed.
John
11-06-21, 09:04 PM
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Originally Posted by 70sSanO
It all depends on whether the STX was running narrow pulleys. 6/7 speed pulleys were wider.
11-06-21, 09:54 PM
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Originally Posted by nathand
It's a 7 speed. The shop that sold me the replacement pulleys also gave me a bolt off a spare derailleur but it's too short.
Not sure what bolt they gave you.
John
Edit Added: Just compare the thickness of the new pulley to the lower pulley.
11-07-21, 10:19 AM
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If you decide on a replacement, Shimano (or compatible) 6- through 9-speed and 10-speed road derailleurs all have compatible cable pull ratios.
11-08-21, 09:51 AM
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I've got that same set of replacement pulleys in my spares box, but haven't tried to use it yet. Both pulleys are identical as far as I can tell, so either one could function as a guide or tension pulley, I guess.
As for the bolt, you might have to buy a donor RD from the same time period, or just buy another 7-speed compatible RD. There are lots out there that would work.
As for the bolt, you might have to buy a donor RD from the same time period, or just buy another 7-speed compatible RD. There are lots out there that would work.
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RUSA #7498
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
11-08-21, 11:05 AM
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Originally Posted by ThermionicScott
As for the bolt, you might have to buy a donor RD from the same time period, or just buy another 7-speed compatible RD. There are lots out there that would work.
11-08-21, 11:50 AM
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Originally Posted by nathand
If I buy a replacement RD, recommendations on whether I should buy the same model (seems there are plenty of used ones on eBay, roughly $25), or upgrade to a used Deore (more like $40 on eBay), or get a more modern low-end 7-speed such as Tourney?
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RUSA #7498
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
11-08-21, 12:26 PM
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Originally Posted by ThermionicScott
If you can find a NOS/NIB/low miles STX-RC, it would be fun to keep it original-spec.
It's the original derailleur on a 1996 Trek 930.
11-08-21, 01:03 PM
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Originally Posted by nathand
For what it's worth, this is an "STX" (no "-RC"). Any idea what the difference is?
It's the original derailleur on a 1996 Trek 930.
It's the original derailleur on a 1996 Trek 930.
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RUSA #7498
Originally Posted by chandltp
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
11-17-21, 02:46 PM
#11
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I stopped by my local bike co-op yesterday. They have a small drawer full of derailleur pulleys and related parts, and I found a bolt that fits although it's clearly not the "right" one. There's maybe a little less side-to-side play in the replacement pulley than with the original guide pulley but the shifting works (a little noisy between the smallest two cogs) so I think I'm set for now.
