Chain Falling Off...
#1
Full Member
Thread Starter
Join Date: Jun 2022
Posts: 294
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 193 Post(s)
Likes: 0
Liked 37 Times
in
32 Posts
Chain Falling Off...
Hi all. Went for a ride with my son this morning. We hit a hill (more like an exaggerated grade) and his chain came off the large chainring (2x10, Tiagra). It's a new set up and the groupo was installed by my LBS. We re-attached the chain and then it happened again on the next ascent! What are some of the common issues that may be causing this? Thank you!
#2
I'm good to go!
Join Date: Jul 2017
Location: Mississippi
Posts: 15,293
Bikes: Tarmac Disc Comp Di2 - 2020
Mentioned: 52 Post(s)
Tagged: 0 Thread(s)
Quoted: 6357 Post(s)
Liked 4,959 Times
in
3,414 Posts
Trying to shift was my thought too. Especially if he is waiting till his cadence is already too low. And also the possibility that shifts aren't getting completed before pedaling is stopped for what ever reason, be it stopping pedaling and coasting briefly for clearance to traffic ahead or stopping just because pedaling became too hard because going to the next easier gear was too late a decision.
#3
Habitual User
Join Date: Jan 2020
Location: Altadena, CA
Posts: 8,238
Bikes: 2023 Niner RLT 9 RDO, 2018 Trek Procaliber 9.9 RSL, 2018 Storck Fascenario.3 Platinum, 2003 Time VX Special Pro, 2001 Colnago VIP, 1999 Trek 9900 singlespeed, 1977 Nishiki ONP
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 5106 Post(s)
Liked 8,419 Times
in
3,976 Posts
Also look for damaged/twisted teeth on the chainring, as well as damaged/twisted chain links.
__________________
"Swedish fish. They're protein shaped." - livedarklions
"Swedish fish. They're protein shaped." - livedarklions
#4
Full Member
Thread Starter
Join Date: Jun 2022
Posts: 294
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 193 Post(s)
Likes: 0
Liked 37 Times
in
32 Posts
Thanks, to be honest he was riding an old school bike with the the old 80's Suntour-type shift levers that didn't click when you switched gears. The new Tiagra setup is totally new to him. He also has some real difficulty thinking simple things through. So maybe he's just not shifting correctly, if that's somehow possible. I really don't know what "cross chained" means. The chain itself is brand spanking new.
#5
Advocatus Diaboli
Join Date: Feb 2015
Location: Wherever I am
Posts: 8,707
Bikes: Merlin Cyrene, Nashbar steel CX
Mentioned: 14 Post(s)
Tagged: 1 Thread(s)
Quoted: 4806 Post(s)
Liked 1,548 Times
in
1,015 Posts
Is the chain falling off to the outside or inside of the big chainring?
Likes For Sy Reene:
#6
Habitual User
Join Date: Jan 2020
Location: Altadena, CA
Posts: 8,238
Bikes: 2023 Niner RLT 9 RDO, 2018 Trek Procaliber 9.9 RSL, 2018 Storck Fascenario.3 Platinum, 2003 Time VX Special Pro, 2001 Colnago VIP, 1999 Trek 9900 singlespeed, 1977 Nishiki ONP
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 5106 Post(s)
Liked 8,419 Times
in
3,976 Posts
Cross-chained is...
1. Being in the small cog at the rear and the small chainring in the front.
2. Being in the large cog at the rear and the large chainring in the front.
It is generally good practice to avoid both of these conditions. Although bike chains have some tolerance for lateral flexibility, it's pretty limited, and everything works best in a straighter line between chainring and cog. These scenarios put the chain at the most extreme angles, and it can cause issues. Because chains, chainrings, and cogs are designed for shifting from lateral pressure by a derailleur, big-big or small-small can cause an unwanted shift just from the lateral pressure caused by the angled chain line. It might also be at the limits of the rear derailleur's capacity, which is also not recommended.
1. Being in the small cog at the rear and the small chainring in the front.
2. Being in the large cog at the rear and the large chainring in the front.
It is generally good practice to avoid both of these conditions. Although bike chains have some tolerance for lateral flexibility, it's pretty limited, and everything works best in a straighter line between chainring and cog. These scenarios put the chain at the most extreme angles, and it can cause issues. Because chains, chainrings, and cogs are designed for shifting from lateral pressure by a derailleur, big-big or small-small can cause an unwanted shift just from the lateral pressure caused by the angled chain line. It might also be at the limits of the rear derailleur's capacity, which is also not recommended.
__________________
"Swedish fish. They're protein shaped." - livedarklions
"Swedish fish. They're protein shaped." - livedarklions
#7
Grupetto Bob
Join Date: Sep 2020
Location: Seattle-ish
Posts: 6,538
Bikes: Bikey McBike Face
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 2737 Post(s)
Liked 6,070 Times
in
3,096 Posts
If the chain is being thrown off the outside of the big ring, your derailleur needs to be adjusted. This is a DIY. Watch this: https://www.parktool.com/en-us/blog/...eur-adjustment
__________________
Road 🚴🏾♂️ & Mountain 🚵🏾♂️
Road 🚴🏾♂️ & Mountain 🚵🏾♂️
Likes For rsbob:
#8
Senior Member
Join Date: Apr 2011
Posts: 7,387
Mentioned: 43 Post(s)
Tagged: 0 Thread(s)
Quoted: 4606 Post(s)
Liked 1,766 Times
in
1,156 Posts
You should ride it to see if you can duplicate the problem, then take it back to the shop that assembled it.
#9
Senior Member
Join Date: Oct 2014
Location: Portland, OR
Posts: 13,014
Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder
Mentioned: 131 Post(s)
Tagged: 0 Thread(s)
Quoted: 4887 Post(s)
Liked 4,052 Times
in
2,627 Posts
Tell us all you can about the shifts where the chain falls off. What gear were you starting in? Where did the chain go? Off the outside or between the chainrings? The more we know, the better we can help. (Maybe you need to take the bike out and see if you can duplicate the events.) Any bike shop will love the same information. What happens on the road cannot always be duplicated on a stand.
#10
Super Moderator
Join Date: Jul 2004
Location: Ffld Cnty Connecticut
Posts: 21,851
Bikes: Old Steelies I made, Old Cannondales
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 1175 Post(s)
Liked 937 Times
in
620 Posts
I would think he was shifting to the smaller front chainring to go up the hill, and it overshifted onto the frame bottom bracket. Correct ?
It may just need a simple adjustment of the 'L' screw to prevent the front derailleur from moving inboard quite as much.
It may just need a simple adjustment of the 'L' screw to prevent the front derailleur from moving inboard quite as much.
__________________
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.
FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
Bikes: Old steel race bikes, old Cannondale race bikes, less old Cannondale race bike, crappy old mtn bike.
FYI: https://www.bikeforums.net/forum-sugg...ad-please.html
#11
Senior Member
Join Date: Aug 2019
Location: Québec, Canada
Posts: 2,161
Bikes: SL8 Pro, TCR beater
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 1027 Post(s)
Liked 595 Times
in
448 Posts
Where? Between the small chainring and the frame or between the bigger chainring and the crank arm?
If it's dropping between the frame and the small chainring when you change gear from the big to the small ring to climb a hill, it's most likely your low limit screw that isn't properly adjusted (your chain gets thrown too far inward). Bring it back to your LBS that installed it; they will adjust it free of charge.
If it's dropping between the frame and the small chainring when you change gear from the big to the small ring to climb a hill, it's most likely your low limit screw that isn't properly adjusted (your chain gets thrown too far inward). Bring it back to your LBS that installed it; they will adjust it free of charge.
Last edited by eduskator; 01-02-24 at 01:15 PM.
#12
Ontheroad
Join Date: Nov 2005
Location: Connecticut
Posts: 64
Bikes: Felt Z2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Likes: 0
Liked 2 Times
in
1 Post
I had the same problem on a new bike that was assembled by my LBS. Changing gears under tension would sometimes cause the chain to come off. After trying various adjustments to no avail, the head mechanic took a look and removed a link from the chain. It seems that when they assembled the bike, they allowed for too many links between the chain ring and the rear cluster. It worked like a charm. I've never had the chain fall off since.
#13
Full Member
Join Date: Jul 2018
Posts: 472
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 159 Post(s)
Liked 255 Times
in
134 Posts
I had the same problem on a new bike that was assembled by my LBS. Changing gears under tension would sometimes cause the chain to come off. After trying various adjustments to no avail, the head mechanic took a look and removed a link from the chain. It seems that when they assembled the bike, they allowed for too many links between the chain ring and the rear cluster. It worked like a charm. I've never had the chain fall off since.
Chain doesn't fall off during a ride. When rolling in reverse to store or such as this. I believe it may be too loose a chain.