Again another post about her bike not mine, it's a couple year old Trek crossover type bike, appears to have all "SRAM 3.0" components except the front der is Shimano something or other. SRAM indexed grip shifts. She was having lots of phantom upshifts on the rear going up hills, and when I took the bike inside to look at it here the cables are all inside a housing from the handlebars all the way to the derailleurs. So what could possibly be the issue? I have no experience setting up indexed shifters; all the bikes I've ever owned save for the Cannondale I bought last week have all been friction. Not sure if that is even the problem. She is neither light nor weak so I'm sure her bike is getting a good amount of stress when climbing. Bike has been more or less sitting for the last few years, unridden. Chain and cogs all looked brand new (except for a nasty twist - see my other post. I would like to rule out all other possibilities before telling her it's good to ride though.)
Should I just tell her to take it to LBS for a "tuneup?"
Again another post about her bike not mine, it's a couple year old Trek crossover type bike, appears to have all "SRAM 3.0" components except the front der is Shimano something or other. SRAM indexed grip shifts. She was having lots of phantom upshifts on the rear going up hills, and when I took the bike inside to look at it here the cables are all inside a housing from the handlebars all the way to the derailleurs. So what could possibly be the issue?
I'm no expert, but in light of the twisted chain...
Again another post about her bike not mine, it's a couple year old Trek crossover type bike, appears to have all "SRAM 3.0" components except the front der is Shimano something or other. SRAM indexed grip shifts. She was having lots of phantom upshifts on the rear going up hills, and when I took the bike inside to look at it here the cables are all inside a housing from the handlebars all the way to the derailleurs. So what could possibly be the issue?
I'm no expert, but in light of the twisted chain...
I agree it's possible, but during the ride the chain fell off the inner front ring and partially sucked at the same time - so I don't know if the chain is the cause or the effect. (I had to manhandle it pretty good to get it out from between the ring and the chainstay, so it might have twisted then.) I'm trying to just make sure I check everything easy before telling her to take it to a pro to look at it.
PS occurs inpart when cables stick in housings when bars are turned. A yearly cable - housing cleaning with thinner and a spoke and or used cable run in and out 10-20 times after thinner sits in cable as U then dry under hot sun or infralamp relube with Finish Line Wax with teflon also U soaked under heat wipe cable clean, drip FL on cable, allow to set place cable back in housing, fill with FL.
often, the PS happens during a temperature drop when drying lubes cross thier threshold of no sick to stick.
Again another post about her bike not mine, it's a couple year old Trek crossover type bike, appears to have all "SRAM 3.0" components except the front der is Shimano something or other. SRAM indexed grip shifts. She was having lots of phantom upshifts on the rear going up hills, and when I took the bike inside to look at it here the cables are all inside a housing from the handlebars all the way to the derailleurs. So what could possibly be the issue? I have no experience setting up indexed shifters; all the bikes I've ever owned save for the Cannondale I bought last week have all been friction. Not sure if that is even the problem. She is neither light nor weak so I'm sure her bike is getting a good amount of stress when climbing. Bike has been more or less sitting for the last few years, unridden. Chain and cogs all looked brand new (except for a nasty twist - see my other post. I would like to rule out all other possibilities before telling her it's good to ride though.)
Should I just tell her to take it to LBS for a "tuneup?"
Start with a new properly sized chain, new cable, and new housing. I would put on the new chain first and see if that did the trick. I would have the housing and cable standing by in case. When you cut the new housing make sure the ends are clean and flat.... I use a Dremel tool with a cutoff wheel. Keep your receipt in case you think it isn't worth changing the cable and housing... and ride the bike back to make it worth getting the refund... at today's gas prices I would ride to the LBS Phantom Shifts and all.
You didn't mention if your wifes bike was a woman's frame, if it is, that is partially the cause. The reason is the flexing of the frame and pedaling hard is causing the cable to move through the plastic guide under the bottom bracket. The solution is cheap, put some dielectric grease on the cable where it goes through the guide (it works as a lubricant and won't corrode plastic). You can get this stuff at any automotive store for 4-5 bucks. It worked on my wifes womans frame. Good luck.
John Henderson said:
Dan O said:
I'm no expert, but in light of the twisted chain...
I missed that bit. A twist in the chain can certainly cause auto-shifting and/or skipping skipping behaviour.
You didn't mention if your wifes bike was a woman's frame, if it is, that is partially the cause. The reason is the flexing of the frame and pedaling hard is causing the cable to move through the plastic guide under the bottom bracket. The solution is cheap, put some dielectric grease on the cable where it goes through the guide (it works as a lubricant and won't corrode plastic). You can get this stuff at any automotive store for 4-5 bucks. It worked on my wifes womans frame. Good luck.
John Henderson said:
Dan O said:
I'm no expert, but in light of the twisted chain...
I missed that bit. A twist in the chain can certainly cause auto-shifting and/or skipping skipping behaviour.
John
It is a ladies' frame (hey, she picked it out, I wasn't involved in the process) but there is no guide down there - the cable is all in housing. However that's a good tip for *my* bike - I was going to use bearing grease but if the silicone will work better I have that too.
You didn't mention if your wifes bike was a woman's frame, if it is, that is partially the cause. The reason is the flexing of the frame and pedaling hard is causing the cable to move through the plastic guide under the bottom bracket. The solution is cheap, put some dielectric grease on the cable where it goes through the guide (it works as a lubricant and won't corrode plastic). You can get this stuff at any automotive store for 4-5 bucks. It worked on my wifes womans frame. Good luck.
John Henderson said:
Dan O wrote:
> I'm no expert, but in light of the twisted chain...
I missed that bit. A twist in the chain can certainly cause auto-shifting and/or skipping skipping behaviour.
John
It is a ladies' frame (hey, she picked it out, I wasn't involved in the process) but there is no guide down there - the cable is all in housing. However that's a good tip for *my* bike - I was going to use bearing grease but if the silicone will work better I have that too.
nate
Hi, you don't want to use any petroleum based lubricants on plastic! That is why the dielectric grease works best. PS, if your wifes cable housing runs under the bracket, pull the steel cable or buy a new one and coatit with the Dieletric grease, it is worth a shot.
Again another post about her bike not mine, it's a couple year old Trek crossover type bike, appears to have all "SRAM 3.0" components except the front der is Shimano something or other. SRAM indexed grip shifts. She was having lots of phantom upshifts on the rear going up hills, and when I took the bike inside to look at it here the cables are all inside a housing from the handlebars all the way to the derailleurs. So what could possibly be the issue? I have no experience setting up indexed shifters; all the bikes I've ever owned save for the Cannondale I bought last week have all been friction. Not sure if that is even the problem. She is neither light nor weak so I'm sure her bike is getting a good amount of stress when climbing. Bike has been more or less sitting for the last few years, unridden. Chain and cogs all looked brand new (except for a nasty twist - see my other post. I would like to rule out all other possibilities before telling her it's good to ride though.)
Should I just tell her to take it to LBS for a "tuneup?"
nate
Phantom shifts are usually caused by frame flex when the frame is used as part of the cable housing (bare cable runs between stops). You usually see this when climbing while standing. If it's not that, it may just be that it's a shifting tweak that's needed. It may be a "slow shift" problem: the cable pulls the derailer inward, the spring pulls it back, if it gets draggy, the spring pull back may be slow.
