Bike Shifting Oddity
June 19, 2010 6:36 AM Subscribe
My bike won't upshift to the large ring in the front when I am on it, but it works fine when it is turned upside down. What gives?
I recently bought a Cannondale Synapse 5 w/ Shimano 105s on it and I'm having a kind of odd problem - when there is pressure on the back tire, I have great difficulty upshifting to the large ring in the front - Most times it doesn't take at all, sometimes if I continue holding the lever for 30 seconds or so it may eventually catch.
The weird part is that if I get off the bike, and flip it upside down, spin the pedals and shift, it shifts flawlessly! WTF?! I've brought it back to the place I purchased the bike 3 times now, but the techs there aren't allowed to actually take the bike out on the road to witness this (in NYC) - They put it up on a trainer where the back wheel was elevated, not touching the ground and it worked fine, so I guess it has something to do with the weight on the back wheel, but I'm no bike tech (yet) and wanted to see if anyone has some ideas for me.
I am aware that not all gear combinations are meant to be used and have asked people to make sure I am on the correct gears on the back hub when trying to upshift to the big ring up front.
For what it's worth this bike only has the 2 rings in the front, no granny gear.
Thanks in advance for any insight. It's kind of driving me insane. Also if anyone has any recommendations for bike shops in NYC or bike forums on the internet that are helpful I'd appreciate it.
I recently bought a Cannondale Synapse 5 w/ Shimano 105s on it and I'm having a kind of odd problem - when there is pressure on the back tire, I have great difficulty upshifting to the large ring in the front - Most times it doesn't take at all, sometimes if I continue holding the lever for 30 seconds or so it may eventually catch.
The weird part is that if I get off the bike, and flip it upside down, spin the pedals and shift, it shifts flawlessly! WTF?! I've brought it back to the place I purchased the bike 3 times now, but the techs there aren't allowed to actually take the bike out on the road to witness this (in NYC) - They put it up on a trainer where the back wheel was elevated, not touching the ground and it worked fine, so I guess it has something to do with the weight on the back wheel, but I'm no bike tech (yet) and wanted to see if anyone has some ideas for me.
I am aware that not all gear combinations are meant to be used and have asked people to make sure I am on the correct gears on the back hub when trying to upshift to the big ring up front.
For what it's worth this bike only has the 2 rings in the front, no granny gear.
Thanks in advance for any insight. It's kind of driving me insane. Also if anyone has any recommendations for bike shops in NYC or bike forums on the internet that are helpful I'd appreciate it.
Also: http://bicycletutor.com
posted by spikeleemajortomdickandharryconnickjrmints at 6:42 AM on June 19, 2010
posted by spikeleemajortomdickandharryconnickjrmints at 6:42 AM on June 19, 2010
Yeah, it sounds to me like the FD isn't pulling the chain over far enough so you need to shorten the cable up some via the methods mentioned above. Shifting does work differently under load so that could easily by why it works fine upside down or on a repair stand.
posted by ghharr at 7:02 AM on June 19, 2010
posted by ghharr at 7:02 AM on June 19, 2010
Best answer: Before you tension your cable, make sure the limit stop (2 small screws on the top of the derailleur; one marked H and one marked L) is allowing the derailleur to move out far enough to push the chain up onto the big ring. It sounds like it isn't, so turn the one labelled H counterclockwise a quarter to a half turn before you tension the cable as described above.
posted by Go Banana at 7:03 AM on June 19, 2010
posted by Go Banana at 7:03 AM on June 19, 2010
This is a pretty weird problem but from what you are describing it sounds like flex in your frame may be throwing off the rear mechanism under load. So I'd second spikelee...jrmints and go banana's solutions, but keep in mind you're doing micro adjustments at this point. Like, start with a quarter turn and see what happens from there.
If that doesn't solve the problem, go to Bike Works on Ridge St in the LES or B's Bikes in Greenpoint. I messengered in this city for years and if those guys can't fix a problem, it's not worth fixing!
posted by johnnybeggs at 7:04 AM on June 19, 2010
If that doesn't solve the problem, go to Bike Works on Ridge St in the LES or B's Bikes in Greenpoint. I messengered in this city for years and if those guys can't fix a problem, it's not worth fixing!
posted by johnnybeggs at 7:04 AM on June 19, 2010
front mech, the front mech. gah.
posted by johnnybeggs at 7:04 AM on June 19, 2010
posted by johnnybeggs at 7:04 AM on June 19, 2010
Response by poster: spikeleemajortomdickandharryconnickjrmints:
This is the allen key part you are talking about eh http://img.skitch.com/20100619-kssg94qtn3ngkx9m61r2as6hx6.jpg
Having some issues finding the adjuster. Could this be it? http://img.skitch.com/20100619-tj8hyjpa6unmqctpnha9m17ujy.jpg
Thanks!
posted by zackola at 7:06 AM on June 19, 2010
This is the allen key part you are talking about eh http://img.skitch.com/20100619-kssg94qtn3ngkx9m61r2as6hx6.jpg
Having some issues finding the adjuster. Could this be it? http://img.skitch.com/20100619-tj8hyjpa6unmqctpnha9m17ujy.jpg
Thanks!
posted by zackola at 7:06 AM on June 19, 2010
I also suspect this is a cable tension issue. Play around with it and see what happens.
This is normal, by the way. Especially since it's a new bike. When you get it perfectly in tune, it may very well start having the same problem again after a few hundred miles. You need to keep making minor adjustments on new cables until they are fully stretched out.
posted by TurkishGolds at 7:32 AM on June 19, 2010
This is normal, by the way. Especially since it's a new bike. When you get it perfectly in tune, it may very well start having the same problem again after a few hundred miles. You need to keep making minor adjustments on new cables until they are fully stretched out.
posted by TurkishGolds at 7:32 AM on June 19, 2010
That first pic is indeed the part you would adjust with an allen wrench.
There should be a barrel adjuster at the point where the cable housing ends and is attached to the frame, probably on the downtube. The thing in your second pic does look like one but that is a weird place for it, you can give that a try as well.
posted by ghharr at 7:34 AM on June 19, 2010
There should be a barrel adjuster at the point where the cable housing ends and is attached to the frame, probably on the downtube. The thing in your second pic does look like one but that is a weird place for it, you can give that a try as well.
posted by ghharr at 7:34 AM on June 19, 2010
Actually you're not "adjusting" anything with the allen wrench, it's just a bolt that holds the cable in place, what you would do would be to pull more of the cable through and secure it with the bolt, sorry if that was unclear.
posted by ghharr at 7:36 AM on June 19, 2010
posted by ghharr at 7:36 AM on June 19, 2010
don't adjust with that allen key until you've tried the other solutions!
posted by johnnybeggs at 7:57 AM on June 19, 2010
posted by johnnybeggs at 7:57 AM on June 19, 2010
The thing in your second pic does look like one but that is a weird place for it, you can give that a try as well.
posted by ghharr
That is definitely a barrel adjuster. Newer/higher-end cable sets come with those for micro adjusting ease.
posted by johnnybeggs at 7:58 AM on June 19, 2010
posted by ghharr
That is definitely a barrel adjuster. Newer/higher-end cable sets come with those for micro adjusting ease.
posted by johnnybeggs at 7:58 AM on June 19, 2010
Google image search "barrel adjuster down tube" to see what people are talking about.
posted by johnnybeggs at 8:06 AM on June 19, 2010
posted by johnnybeggs at 8:06 AM on June 19, 2010
Best answer: Zackola: In your first photo, there are two screwheads facing up / facing the camera to the right of the the Allen-head bolt you pointed at. Those are the 'H' and 'L' screws Go Banana referred to. (That Allen-head bolt is the derailleur's mounting bolt. Don't mess with it except as a last resort. If the bike has ever shifted correctly, then the derailleur is already mounted correctly.)
The 'H' screw is to prevent the derailleur moving so far enough outboard as to push the chain over and off the big ring to the outside. It sounds like yours is just slightly too tight and is preventing the derailleur moving far enough to even shift onto the big ring. Slacking it should get you more positive shifting. 1/4-turns at a time, as others have said.
posted by TruncatedTiller at 8:12 AM on June 19, 2010
The 'H' screw is to prevent the derailleur moving so far enough outboard as to push the chain over and off the big ring to the outside. It sounds like yours is just slightly too tight and is preventing the derailleur moving far enough to even shift onto the big ring. Slacking it should get you more positive shifting. 1/4-turns at a time, as others have said.
posted by TruncatedTiller at 8:12 AM on June 19, 2010
(That Allen-head bolt is the derailleur's mounting bolt. Don't mess with it except as a last resort. If the bike has ever shifted correctly, then the derailleur is already mounted correctly.)
It's not the mounting bolt, that is on the other side of the seat tube. You can see in his picture that it is the bolt securing the cable, which is ok to fiddle with, but as mentioned above should only really be done if using the barrel adjusters isn't adequate.
posted by ghharr at 8:46 AM on June 19, 2010
It's not the mounting bolt, that is on the other side of the seat tube. You can see in his picture that it is the bolt securing the cable, which is ok to fiddle with, but as mentioned above should only really be done if using the barrel adjusters isn't adequate.
posted by ghharr at 8:46 AM on June 19, 2010
As to why it works when off the ground, my guess is that it has to do with the tension in the chain. The rear wheel freewheeling in the air doesn't provide much resistance at all so it's hard to develop much tension in the chain, compared to when you're actually riding the bike and you have the entire momentum of yourself and the bike to work against (even though you aren't supposed to try to shift while pedaling hard.) A chain under tension will be harder for the derailleur to deflect and it sounds like it's currently just at the edge of being able to deflect the chain sufficiently under little tension that it fails under normal tension.
posted by Rhomboid at 10:47 AM on June 19, 2010
posted by Rhomboid at 10:47 AM on June 19, 2010
I had this exact same problem on my new Cannondale -- I have the Synapse 5 with the 105 components, but last year's model and the women's frame. I could only shift up to the big chain ring with a lot of heinous grinding and holding down the lever for about 20 seconds. I never tried shifting with it turned upside down.
I took it back to the shop where I bought it and a few minutes worth of adjustments fixed it the problem. Unfortunately I can't advise you on the adjustment because I have no idea what they did to it. All I can offer is another datapoint that might indicate this is a common Synapse quirk, and the reassurance that a decent bike shop should be able to fix it in a snap.
posted by c lion at 10:59 AM on June 19, 2010
I took it back to the shop where I bought it and a few minutes worth of adjustments fixed it the problem. Unfortunately I can't advise you on the adjustment because I have no idea what they did to it. All I can offer is another datapoint that might indicate this is a common Synapse quirk, and the reassurance that a decent bike shop should be able to fix it in a snap.
posted by c lion at 10:59 AM on June 19, 2010
Best answer: Yes and yes.
You have a barrel (or in-line) adjuster coming right out of your shifter (that's nice). You probably have another one on the downtube. This gives you a bit more adjustment to use, which is a good thing.
Turning the adjusters is the easy and quick fix. If that doesn't solve it, then work with the H/L screws (you'll want to turn the H screw, which will move the derailleur in/out when it's on the big ring). Make little adjustments, test, make them again.
If you get it too far out of whack, take it to the shop mentioned above. This is a 5 minute fix, and ask if you can watch.
Doing this yourself really helps you understand exactly what's happening when you move your shift lever. Hand-->lever-->cable-->derailleur-->chain-->cog. Once you understand what's happening without having to process the mechanics in your head, you'll be able to reach down and turn your adjuster in/out a 1/4 turn while riding at full speed and not even think about it.
Not to get all zen on you, but play around and see how the screws affect the behavior of the derailleur.
posted by spikeleemajortomdickandharryconnickjrmints at 11:19 AM on June 19, 2010
You have a barrel (or in-line) adjuster coming right out of your shifter (that's nice). You probably have another one on the downtube. This gives you a bit more adjustment to use, which is a good thing.
Turning the adjusters is the easy and quick fix. If that doesn't solve it, then work with the H/L screws (you'll want to turn the H screw, which will move the derailleur in/out when it's on the big ring). Make little adjustments, test, make them again.
If you get it too far out of whack, take it to the shop mentioned above. This is a 5 minute fix, and ask if you can watch.
Doing this yourself really helps you understand exactly what's happening when you move your shift lever. Hand-->lever-->cable-->derailleur-->chain-->cog. Once you understand what's happening without having to process the mechanics in your head, you'll be able to reach down and turn your adjuster in/out a 1/4 turn while riding at full speed and not even think about it.
Not to get all zen on you, but play around and see how the screws affect the behavior of the derailleur.
posted by spikeleemajortomdickandharryconnickjrmints at 11:19 AM on June 19, 2010
Response by poster: Thanks for all the advice - about to go try out some barrel adjusting.
posted by zackola at 7:32 AM on June 20, 2010
posted by zackola at 7:32 AM on June 20, 2010
I don't think it is weight or flex that is causing this problem, I think it is tension on the chain. Under tension, front derailleurs need to move considerably further to still cause a shift. Another possibility, are you trying to shift into the big ring up front while you are also in the big gear on the back (3-1 in numbers, I guess). While I guess it is supposed to be possible, don't waste your time worrying about this shift. In the middle chain ring on the front you can use all the back gears, but in the small ring you should only ever use the bigger half of the back gears, and in the big ring you should only ever use the smaller half of the back gears.
To determine if the high limit screw is set well, put the bike in the big ring, grab the front derailleur cable and pull firmly (you can pull in any direction, no need to pull axially, you just want to put a lot of tension on it. This will show you the furthest outward position the derailleur can reach with that limit screw setting. It should be a little further to the outside than centre over the large ring--touching the chain on the inside is a little too much, but it should be pretty close to touching.
Adjusting the front dérailleur using the allen key and tensioning the cable manually is a big pain in the ass. Certainly doable, but front derailleurs have quite a strong spring, and you run out of hands quickly :)
Finally, the store not fixing this is ridiculous, but sadly typical of my experience with bike stores. If they put it on a trainer, do they get on and ride while the trainer is set to highest resistance setting? If the trainer is resisting hard, and they try to shift at high cadence, it should be a pretty good simulation of riding on the road..
posted by Chuckles at 8:06 AM on June 20, 2010
To determine if the high limit screw is set well, put the bike in the big ring, grab the front derailleur cable and pull firmly (you can pull in any direction, no need to pull axially, you just want to put a lot of tension on it. This will show you the furthest outward position the derailleur can reach with that limit screw setting. It should be a little further to the outside than centre over the large ring--touching the chain on the inside is a little too much, but it should be pretty close to touching.
Adjusting the front dérailleur using the allen key and tensioning the cable manually is a big pain in the ass. Certainly doable, but front derailleurs have quite a strong spring, and you run out of hands quickly :)
Finally, the store not fixing this is ridiculous, but sadly typical of my experience with bike stores. If they put it on a trainer, do they get on and ride while the trainer is set to highest resistance setting? If the trainer is resisting hard, and they try to shift at high cadence, it should be a pretty good simulation of riding on the road..
posted by Chuckles at 8:06 AM on June 20, 2010
Response by poster: The barrel adjuster was totally loose! As in was just spinning around the cable and not catching doing anything - so I tightened that up and it made this slightly more tolerable, instead of absolutely never upshifting to the top ring, sometimes it caught after about 10 seconds - Still was unacceptable.
I checked the high limit screw, by doing a 1/2 turn counter clockwise, pedaling around, then the chain came off towards the outside (pedal) so I dialed that back by a 1/4 turn and that seems to have made things much better. Seems to have reliably shifted ~ 10 times in a row which is a new record. We'll see if this holds.
I have a feeling the tension on the cable is still a little loose so I'm going to probably deal with this after I put another hundred or so miles on it, unless there's something wrong with having the barrel adjuster tightened this much http://img.skitch.com/20100620-kraa4ppukks63mn4dx1s2exe97.jpg
Thank you for all your help. Seriously awesome! I've got a pretty good mental picture now of how the front derailleur works now, and some trustworthy sounding shops to go to when I need to.
posted by zackola at 11:52 AM on June 20, 2010
I checked the high limit screw, by doing a 1/2 turn counter clockwise, pedaling around, then the chain came off towards the outside (pedal) so I dialed that back by a 1/4 turn and that seems to have made things much better. Seems to have reliably shifted ~ 10 times in a row which is a new record. We'll see if this holds.
I have a feeling the tension on the cable is still a little loose so I'm going to probably deal with this after I put another hundred or so miles on it, unless there's something wrong with having the barrel adjuster tightened this much http://img.skitch.com/20100620-kraa4ppukks63mn4dx1s2exe97.jpg
Thank you for all your help. Seriously awesome! I've got a pretty good mental picture now of how the front derailleur works now, and some trustworthy sounding shops to go to when I need to.
posted by zackola at 11:52 AM on June 20, 2010
The barrel adjuster should always be screwed in at least 1.5 turns. Looser than that, and you might damage the thread.
posted by Chuckles at 1:42 PM on June 20, 2010
posted by Chuckles at 1:42 PM on June 20, 2010
This thread is closed to new comments.
Look for the barrel adjustment that's on the frame, or the one that's on the derailleur. It's grey or black plastic, and the cable runs through it. Turn it counterclockwise (to make it pull out, and therefore putting more tension).
Give it a few turns and ride. If you need more tension, give it a couple of more turns. It should be positioned so that you can reach it while you're riding. If you run out of room with the adjuster, then thread it almost all of the way in and adjust the cable tension with a 5mm allen wrench at the derailleur (where the cable is pinched to the body of the derailleur).
Let me know if that doesn't make sense.
posted by spikeleemajortomdickandharryconnickjrmints at 6:41 AM on June 19, 2010