Grinding
10-16-18 | 09:20 PM
#1
Thread Starter
Senior Member
Joined: Aug 2018
Posts: 2,919
Likes: 4,815
From: Allen, TX
Bikes: 2021 S-Works Turbo Creo SL, 2020 Specialized Roubaix Expert
Grinding
I’ve put about 1,200 miles on my new Specialized Diverge Comp and had to adjust the front and rear derailleurs tonight. It wasn’t wanting to shift into the highest gear and i was hearing a slight drag on the front derailleur in the large chainring. After making the adjustments I ran the bike around a bit to make sure the bike would shift into all gears. And it does.
But I noticed a creaking/grinding noise when pedaling hard on the drive side crank (not the left crank) when in the top four gears. (Largest chain ring, smallest four cogs on the cassette.) This is only when moving relatively slowly, and I don’t normally ride in the top four gears while moving slowly, so maybe it doesn’t matter. The noise goes away when moving a bit faster even with what seems like similar force on the crank.
The noise sounds like the chain rubbing on the front derailleur. Kind of like 4-5 fast clicks. I slacked off the high limit screw. Still have the noise. I’ve adjusted the high limit screw to the point that the derailleur is centered on the chain and still have the noise. The chainring bolts are tight.
Is this simply the cranks or frame flexing? Does it matter?
-Matt
But I noticed a creaking/grinding noise when pedaling hard on the drive side crank (not the left crank) when in the top four gears. (Largest chain ring, smallest four cogs on the cassette.) This is only when moving relatively slowly, and I don’t normally ride in the top four gears while moving slowly, so maybe it doesn’t matter. The noise goes away when moving a bit faster even with what seems like similar force on the crank.
The noise sounds like the chain rubbing on the front derailleur. Kind of like 4-5 fast clicks. I slacked off the high limit screw. Still have the noise. I’ve adjusted the high limit screw to the point that the derailleur is centered on the chain and still have the noise. The chainring bolts are tight.
Is this simply the cranks or frame flexing? Does it matter?
-Matt
10-16-18 | 10:11 PM
#2
Senior Member
Joined: Feb 2012
Posts: 19,353
Likes: 5,471
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
The first thing I think of is a chain getting worn and not meshing with the cogs as nicely as when new. Next is the fix all that so many go to so quickly, bent hanger. The hesitation to shift into the small cog suggests either a worn chain or a bent hanger as also does the noise. Both are easy to check out. If you're not sure how to do so or not comfy with your judgment how about letting the shop you got it from have a look at it.
1200 miles is usually considered a bit low for a chain wear issue. But I have seen bikes with less miles and worn out chains before. What rear cogs do you use most frequently? The smaller the cogs usually used the faster they and the chain wear. (Riding at 10MPH in a 100+ inch gear means a cadence of less then 30). As the cog size decreases the forces that occur with each link/tooth engagement increases (look up chordal action). In many industries a 17T cog is the smallest to insure a smooth power delivery.
I seriously doubt the frame or crank flex is an issue. Andy
1200 miles is usually considered a bit low for a chain wear issue. But I have seen bikes with less miles and worn out chains before. What rear cogs do you use most frequently? The smaller the cogs usually used the faster they and the chain wear. (Riding at 10MPH in a 100+ inch gear means a cadence of less then 30). As the cog size decreases the forces that occur with each link/tooth engagement increases (look up chordal action). In many industries a 17T cog is the smallest to insure a smooth power delivery.
I seriously doubt the frame or crank flex is an issue. Andy
__________________
AndrewRStewart
AndrewRStewart
10-17-18 | 10:08 AM
#3
Thread Starter
Senior Member
Joined: Aug 2018
Posts: 2,919
Likes: 4,815
From: Allen, TX
Bikes: 2021 S-Works Turbo Creo SL, 2020 Specialized Roubaix Expert
I threw a chain a few hundred miles ago and twisted it ever so slightly. I replaced it about 300 miles ago. I haven't measured it for stretch, but it *should* be good. I wasn't sure if the twisted chain might have prematurely worn the cassette or not. I'm preparing for a century ride this weekend and went ahead and replaced the cassette last night, so there was literally no wear on the cogs.
I did check the derailleur hanger and it *appears* to be straight, but it's hard to tell without a derailleur gauge. I did suspect the hanger might be slightly bent as I've had two minor falls on the right side of the bike, but there's no road rash on the derailleur itself. Maybe if I take the hanger off and look at it on a surface plate I can tell if it's bent.
-Matt
I did check the derailleur hanger and it *appears* to be straight, but it's hard to tell without a derailleur gauge. I did suspect the hanger might be slightly bent as I've had two minor falls on the right side of the bike, but there's no road rash on the derailleur itself. Maybe if I take the hanger off and look at it on a surface plate I can tell if it's bent.
-Matt
10-17-18 | 02:20 PM
#4
Senior Member
Joined: Dec 2015
Posts: 916
Likes: 468
From: San Diego
Bikes: 1978 Bruce Gordon, 1977 Lippy, 199? Lippy tandem, Bike Friday NWT, 1982 Trek 720, 2012 Rivendell Atlantis, 1983 Bianchi Specialissima? 1998 Serotta Atlanta, 1981 Dave Moulton
I wonder if some fresh lube on the chain might take care of the problem?
10-17-18 | 02:46 PM
#5
Member
Joined: Mar 2018
Posts: 48
Likes: 1
From: PNW
Bikes: 90's Norco Nitro, 90's Softride traveler, 90's Jamis Dakota, 84 Schwinn High Sierra,
Grinding on one side and not the other leads me down the path of check your pedal on the drive side to make sure it's tight maybe a little Lube on the threads before tightening... Also bearings in pedals can go bad. It seems like lately in me neck of the woods... Proper torque values on pedals is ignored and pedals are left loose.
So you adjusted the limit screw... Did you tension the cable A bike that new probably still qualifies for a free tune up at the shop you got it at right? Maybe use this for getting that hanger checked and have the internal routed cable checked end to end and all points in between.
But the falls and twisted chain all of that can bend a hanger and the only way to check it accurately is with the tool so this is a shop job unless you want to invest in the tool but you could just buy a new hanger and keep the job in house.
So you adjusted the limit screw... Did you tension the cable A bike that new probably still qualifies for a free tune up at the shop you got it at right? Maybe use this for getting that hanger checked and have the internal routed cable checked end to end and all points in between.
But the falls and twisted chain all of that can bend a hanger and the only way to check it accurately is with the tool so this is a shop job unless you want to invest in the tool but you could just buy a new hanger and keep the job in house.
Last edited by MobiBike; 10-17-18 at 02:51 PM. Reason: Final thoughts
10-18-18 | 07:18 AM
#6
Member
Joined: Mar 2018
Posts: 48
Likes: 1
From: PNW
Bikes: 90's Norco Nitro, 90's Softride traveler, 90's Jamis Dakota, 84 Schwinn High Sierra,
One more thing
Pick the bike up and spin that back wheel forward fast and see if the top chain sags down a little bit while the wheel is turning forward. If it does that could also cause the grinding sound as the chain drags on the bottom of the front derailleur cage. A flat pedal stroke from one leg would cause it to drag while riding the smaller cogs in the back. The freehub body may have a string or twine or some other thing wrapped in behind it which causes extra friction.
finding the cause of the initial thrown change that got twisted has me thinking a little bit harder than I probably need to. The other thing that might be going on is a loose bottom bracket or crank arm so to speak. The front derailleur itself may have also been damaged during the Twisted chain episode and of course the rear derailleur pulley wheel cage might have been twisted or any number of other hard to see bends.
finding the cause of the initial thrown change that got twisted has me thinking a little bit harder than I probably need to. The other thing that might be going on is a loose bottom bracket or crank arm so to speak. The front derailleur itself may have also been damaged during the Twisted chain episode and of course the rear derailleur pulley wheel cage might have been twisted or any number of other hard to see bends.
10-23-18 | 08:47 AM
#7
Thread Starter
Senior Member
Joined: Aug 2018
Posts: 2,919
Likes: 4,815
From: Allen, TX
Bikes: 2021 S-Works Turbo Creo SL, 2020 Specialized Roubaix Expert
Well, after riding the bike for about 60 miles the sound is gone. I'm relatively sure it was the FD dragging. I'm just not sure why it was only while hard pedaling on the drive side crank only unless it was slight flexing of the crank or BB.
Thanks for the input, folks.
-Matt
Thanks for the input, folks.
-Matt
Thread
Thread Starter
Forum
Replies
Last Post
vol
Bicycle Mechanics
5
11-03-13 10:36 PM
fronesis
Bicycle Mechanics
10
10-25-13 04:10 PM
