I can repack a bottom bracket, true rims, adjust the front derailier and adjust brakes. I have never had success adjusting this confounded mechanism since I started working on bikes 30 years ago! Can anyone lend a hand in getting this thing adjusted? I had planned on joining the boulder bike co-op but then covid hit and they are no longer offering their classes or expertise.
Looking for rear derailer help on my sons mtn bike.
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r.swany
Rising Sun Member
Is it just delayed shifting? or shifting off the cassette into the spokes? I can def walk you through troubleshooting and, at at least help you fix what you can with on-hand tools. The most common shifting issue with kids bikes is a bent derailleur hanger, in which case the quickest fix is a derailleur hanger alignment tool. Happy to hop on facetime or something and give you some tips!
I was going to say the same. Bent hanger can make it really frustrating. Hard to fix without proper tool. Most bike shop grade bikes have replaceable hangers.
For initial set up adjust the high gear limit screw without the cable attached. (Chain on high gear) Thread the adjustment barrel almost all the way in first and connect the shift cable. Once the cable is connected use the adjustment barrel to tension the cable. Shift the derailleur all the way up into the low gear and set that limit screw. Make fine adjustment with the barrel. The chain should set directly below each cassette gear riding on the upper derailleur pulley.
If that does not work you’ll have to trouble shoot. Bent hanger #1 on kids bike. Cable and housing may need replacement due to contamination or damage. Lubing the derailleur pivots. Shifters rarely go bad without obvious damage.
That’s about all I can do from a distance.
For initial set up adjust the high gear limit screw without the cable attached. (Chain on high gear) Thread the adjustment barrel almost all the way in first and connect the shift cable. Once the cable is connected use the adjustment barrel to tension the cable. Shift the derailleur all the way up into the low gear and set that limit screw. Make fine adjustment with the barrel. The chain should set directly below each cassette gear riding on the upper derailleur pulley.
If that does not work you’ll have to trouble shoot. Bent hanger #1 on kids bike. Cable and housing may need replacement due to contamination or damage. Lubing the derailleur pivots. Shifters rarely go bad without obvious damage.
That’s about all I can do from a distance.
This is an older fuji but it is an entry level model. I'll have to check but I'm pretty sure the hanger is part of the frame. As far as I can tell it doesn't move enough and it has the worthless (imho) gripshift setup.
60wag
Rising Sun Member
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- Aug 23, 2005
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Sometimes, the one piece steel hanger is easier to straighten than the bolt-on aluminum ones. As long as the threads are in good shape, the tool works. With the aluminum bolt-ons, sometimes the aluminum cracks, or the tiny screws holding it in place break off.
I also start by removing the cable and working on the end stop screws while trying to determine if things are square.
Getting it to shift and hold gear first before connecting the cable and messing with indexing issues can really help narrow it down.
I'm not sure replaceable drop outs make shifting service easier, they just makes the frame easier to repair and more modular. Its another part that can move or come loose and inpact shifting.
Getting it to shift and hold gear first before connecting the cable and messing with indexing issues can really help narrow it down.
I'm not sure replaceable drop outs make shifting service easier, they just makes the frame easier to repair and more modular. Its another part that can move or come loose and inpact shifting.
r.swany
Rising Sun Member
Most steel frames typically have integrated hangers, but aluminum frames are usually replaceable. Whether the hanger is removable or not, it doesn't have to be bent very much and it will throw the pulley swing off and cause problems. The easiest way to see if its bent without a tool is to shift to the lowest gear and verify that the pulleys are tracking in-line with the largest cog of the cassette. If the top pulley is further toward the spokes than he cog, and/or the lower pulley is even farther inboard, its most likely the hanger. If that's the case, it totally possible to straighten it "good enough" by eye, just remove the derailleur and use an adjustable crescent wrench to clamp down on the hanger and slowly pull back until the face of the hanger looks parallel to the cassette. Be careful though because as @60wag said if its aluminum it can be brittle (and those little nuggets aren't cheap!)
If all that looks good then next step is to follow the steps @Corbet laid out for setting up a derailleur. There is one step however I would add to the beginning of his list which is checking the B screw adjustment. They always seem to come from the factory too far in, and in the case of older bikes at some point somebody has messed with it and it's not in the correct place. To check it's position have the chain in small cog in back with the cable removed. Adjust the B screw in or out to make the guide pulley (top pulley) as close to the cog as possible without actually hitting it. This will help that guide pulley track the chain as close to the cassette as possible. I guess it's also worth noting that there are also compatibility issues between derailleurs and different sized cassettes. Just mentioning in case you have up-sized the cassette at some point (to have a larger low gear) in which case the throw of the current derailleur may not have a compatible swing and causing shifting issues.
Another cause for poor shifting to consider is a worn out chain. Or what's even more common for folks is using a new chain on a worn out cassette. Over time as the pins, and the ID of the chain rollers wear down, and the chain effectively gets longer (chain stretch). Over time the stretched chain wears the drive edge of the teeth of cogs and chain rings. The system works alright until you put on a new chain which doesn't fit with the worn teeth. Its not always obvious, but the first sign of an issue with that is sticky, delayed or ghost shifting in the rear derailleur.
Sorry for the info dump. You might already know all of this, but you mentioned that rear derailleurs give you fits and there are a lot of reasons why following the basic step-by-step setup process might not yield a functioning derailleur. happy to hop on a call if you want more help working through it!
If all that looks good then next step is to follow the steps @Corbet laid out for setting up a derailleur. There is one step however I would add to the beginning of his list which is checking the B screw adjustment. They always seem to come from the factory too far in, and in the case of older bikes at some point somebody has messed with it and it's not in the correct place. To check it's position have the chain in small cog in back with the cable removed. Adjust the B screw in or out to make the guide pulley (top pulley) as close to the cog as possible without actually hitting it. This will help that guide pulley track the chain as close to the cassette as possible. I guess it's also worth noting that there are also compatibility issues between derailleurs and different sized cassettes. Just mentioning in case you have up-sized the cassette at some point (to have a larger low gear) in which case the throw of the current derailleur may not have a compatible swing and causing shifting issues.
Another cause for poor shifting to consider is a worn out chain. Or what's even more common for folks is using a new chain on a worn out cassette. Over time as the pins, and the ID of the chain rollers wear down, and the chain effectively gets longer (chain stretch). Over time the stretched chain wears the drive edge of the teeth of cogs and chain rings. The system works alright until you put on a new chain which doesn't fit with the worn teeth. Its not always obvious, but the first sign of an issue with that is sticky, delayed or ghost shifting in the rear derailleur.
Sorry for the info dump. You might already know all of this, but you mentioned that rear derailleurs give you fits and there are a lot of reasons why following the basic step-by-step setup process might not yield a functioning derailleur. happy to hop on a call if you want more help working through it!
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Based on my prior experience entry level gripshift is likely the cause. There is a considerable amount of cable friction in those shifters for the derailleur spring to overcome. But make sure the cable is greased inside the housing also.