Thorn Cycles Forum
Community => Thorn General => Topic started by: crazytraveler on March 30, 2014, 06:11:27 pm
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I have noises and feel a bit of vibration everytime I pedal, when me left leg reach the lower position more or less.
I only feel it when pedaling hard, or when I stand up. Could it be about how tight are the screws of the bottom bracket? Should I tight it more until it stops or less and less?
Thanks!
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Hi CT!
Yes, the noise could be caused by a loose bottom bracket eccentric, or...
• Loose or worn pedals
• Loose chainring bolts
• Tight chain link
• Worn bottom bracket bearings.
"Vibration" points the finger toward the drivetrain. Absent that, the cause(s) could be...
• Slightly loose seatpost bolt
• Slightly loose saddle rail clamp
• If you have a Brooks saddle, the rails may be "working" in the rear cantle plate enough to cause the noise; inverting the bike and applying a drop of oil can fix the problem. I just did this myself.
If the noise goes away when you stand and pedal, then suspect something in the rider-support end of things.
A quick search of the Forum archives for "Eccentric" or "Bottom Bracket" should turn up a wealth of information for you. I made a little tutorial on how to quickly and effectively search the forum for answers here: http://www.thorncycles.co.uk/forums/index.php?topic=4390.0 A copy of the Thorn owner's manual details the chain tensioning procedure and offers torque specs for the eccentric bottom bracket grub screws and can be found in PDF form here: http://www.thorncycles.co.uk/thornpdf/ThornBikeOwnerManual2Web.pdf
Hope this helps.
Best,
Dan.
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Hi CT!
Yes, the noise could be caused by a loose bottom bracket eccentric, or...
• Loose or worn pedals
• Loose chainring bolts
• Tight chain link
• Worn bottom bracket bearings.
"Vibration" points the finger toward the drivetrain. Absent that, the cause(s) could be...
• Slightly loose seatpost bolt
• Slightly loose saddle rail clamp
• If you have a Brooks saddle, the rails may be "working" in the rear cantle plate enough to cause the noise; inverting the bike and applying a drop of oil can fix the problem. I just did this myself.
If the noise goes away when you stand and pedal, then suspect something in the rider-support end of things.
A quick search of the Forum archives for "Eccentric" or "Bottom Bracket" should turn up a wealth of information for you. I made a little tutorial on how to quickly and effectively search the forum for answers here: http://www.thorncycles.co.uk/forums/index.php?topic=4390.0 A copy of the Thorn owner's manual details the chain tensioning procedure and offers torque specs for the eccentric bottom bracket grub screws and can be found in PDF form here: http://www.thorncycles.co.uk/thornpdf/ThornBikeOwnerManual2Web.pdf
Hope this helps.
Best,
Dan.
When I stand and pedal is when more noise it makes. As I just readjusted the bottom bracket I imagine the problem is from there, but it was already making a bit of noise before (but only in really hard climbs before).
I had problems readjusting the bottom bracket, since it was stuck in the original position and it was really hard to move for the first time. Just in case that could develop in any further problems.
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I wonder too about the possibility of a loose crank bolt. No harm in checking the torque on those.
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Hi
I experienced this twice when I had an RST. First time was due to loose chainring bolts. Not easy to spot. The second time was cause by the EBB; the screws had not located properly and the EEB had moved a few mm sideways causing an 'oval' groove rather than round, if that makes sense. I removed a couple of links from the chain and started again with the EEB. Solved the problem. Hope this helps.
ian
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I have play and/or tighten the saddle, the seatpost and the eccentric bottom bracket and I still have problems.
When I get propper tools I will try the pedal and the crankset...
Thanks for the help, I will let you know how it evolves.
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Are you sure it is coming from the bottom bracket? If the rear wheel is bolted too tightly in the dropouts you can get a grinding from the bearings when pedalling hard.
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Are you sure it is coming from the bottom bracket? If the rear wheel is bolted too tightly in the dropouts you can get a grinding from the bearings when pedalling hard.
That could be! How to know how tight is it supposed to be?
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Do you use quick release cam-type attachment or what?
I use pit-locks with skewers. I have a big key-ring through the pit-lock tool and just go finger-tight with that keyring.
With a QR cam lever, it shouldn't be too hard to get that lever over the hump and fully snapped shut.
There must be a way to quantify this but it doesn't seem so easy!
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I use pit-locks with skewers. I have a big key-ring through the pit-lock tool and just go finger-tight with that keyring.
With a QR cam lever, it shouldn't be too hard to get that lever over the hump and fully snapped shut.
There must be a way to quantify this but it doesn't seem so easy!
Tools, handles and knobs are scaled to fastener or shaft size for correct torque. Tell us the diameter of the key ring for an approximation, Jim, and we're halfway there.
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the diameter of the key ring
I've got my pitlock key and my Kryptonite key together on a 3.5 cm diameter keyring. The pitlock doesn't see much action but that Kryptonite New York Standard U-Lock is core technology for me!
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Iquote author=crazytraveler link=topic=8759.msg59581#msg59581 date=1396199487]
I have noises and feel a bit of vibration everytime I pedal, when me left leg reach the lower position more or less.
I only feel it when pedaling hard, or when I stand up. Could it be about how tight are the screws of the bottom bracket? Should I tight it more until it stops or less and less?
Thanks!
[/quote]
Tightened my chain other day JUST after changing the oil and it felt crunchy!! Worrying when I had just changed the oil. Either way sure it is the eccentric. Near certain I have over tightened the eccentric. Have no way of taking pedals off to check eccentric but when I pulled them out a bit they had some decent "dents" from tightening. Started to feel better after about 30 miles but still a bit "crunchy ". Can't see what I can do about it other than wait till the chain gets slack and re tighten? Do the new Thorns have a different tightening method. Think I saw one with Allen key bolts? Do you think it is worth filing of the points on the bolts? Spread the pressure? Thorn Enduro Raven by the way, I think it is, away at the moment so can't check.
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Don't think you can overtighten the eccentric other than risking stripping the threads on the bolts. Can't see how it would cause a noise or crunchiness by tightening it.
Filing the points off the bolts would be a bad idea, the points are necessary to dig into the alloy of the eccentric to stop it moving.
The crunchiness is probably just a wear issue and may ease off as the chain and sprocket/chainring bed in to each other, otherwise it will be time to change the chain and turn the sprocket and chainring possibly.
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One thing: best not to over-tighten the chain! You want to leave some slack in the chain! If the chain is really tight, it stresses the hub bearings. When the chain is too tight, the bearings can give a crunchy feel. I don't know the exact spec but you want a good inch of play in the chain up and down mid way along the stays.
The downside of the dimple-style EBB is you don't get fine adjustment. The dimples need to be spaced far enough apart that they don't merge. So you can't loosen the chain just a little. You have to back off to the next dimple, or make a new one if there is enough room. It doesn't really matter about the lack of fine adjustment - you can have a fair bit of play in the chain and it won't fall off, which is really all that matters.
To keep an eye on the dimples and insure proper spacing, I just pull one of the EBB screws all the way out and look down the hole, using a headlamp for illumination. The dimples under the other screw should match exactly. When I see either the best existing dimple - giving a bit of slack but not too much - then I tighten down the one screw, then put back in the screw that I had removed. Or if there is enough space to make a new dimple, same process, I can see the space, tighten the screw that's in place, then tighten the second screw.
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Not to tight but I should have left it alone as the slack was not excessive.
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UPDATE.
I am still not sure where the problem is coming from, but defenetely from the "pedal area".
I have tighten harder the chainring bolt (that's the base of the pedal right?) And the pedals as hard as possible; I have move around the eccentric bottom bracket with no change either...
Chain doesn't look too tight.
Maybe something is worn out? But what? And how to check what? I have only riden 4500Km.
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I solved my last similar puzzle by putting on new pedals. I got some VP-191 pedals, that I learned about from Andre, off ebay for $15. Swapped them in and my annoying noise disappeared! If you have a spare pair of pedals, it's an easy thing to try. And if you don't, you can just get some inexpensive pedals as a diagnostic test. And you might find you like the new pedals!
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Did you take the chain off the sprockets at all ?
If your chainring and sprocket are even number of teeth each (e.g., 40*16) it will wear so that if you unship the chain and it goes back on to a tooth on an inner chain plate where previously it was an outer (e.g., out by 1 tooth) it can be very noisy.
I know this from experience. Its been discussed here before and some folks mark the rear sprocket so as 1 tooth is always noticeable, and they mount the chain on an outer plate on that tooth.
Odd number of teeth, then it won't matter.
Bad luck man.
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Did you take the chain off the sprockets at all ?
If your chainring and sprocket are even number of teeth each (e.g., 40*16) it will wear so that if you unship the chain and it goes back on to a tooth on an inner chain plate where previously it was an outer (e.g., out by 1 tooth) it can be very noisy.
I know this from experience. Its been discussed here before and some folks mark the rear sprocket so as 1 tooth is always noticeable, and they mount the chain on an outer plate on that tooth.
Odd number of teeth, then it won't matter.
Bad luck man.
42*17.
Anyways I moved the chain one up and it still make the same noise. I replaced the link for a new one as well and that didn't help.
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I solved my last similar puzzle by putting on new pedals. I got some VP-191 pedals, that I learned about from Andre, off ebay for $15. Swapped them in and my annoying noise disappeared! If you have a spare pair of pedals, it's an easy thing to try. And if you don't, you can just get some inexpensive pedals as a diagnostic test. And you might find you like the new pedals!
I will try that, but I got new pedals 1 month ago and the sound didnt start at the same time.
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I agree with Jim about trying a pedal swap. You've got to try these noises systematically. Start with removing the pedals, try and get some grease into them if they are the serviceable type, regrease the threads and reattach. If problem persists, take the cranks off one at a time, regrease taper and reattach. If still a problem check the EBB for nice discrete dimples and tightly secure the bolts. Next you need to check the chain for a damaged link, the chainring and the sprocket for any burring. Also check for loose chainring bolts. After that I would check the saddle rails. Then is probably the time to think about the BB.
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Yeah if the pedals are new... that is a classic sort of failure situation, where a new thing develops a problem right away. It's easy to swap different pedals in. Just go out for a mile spin and you'll know if the pedals were are problem. Just borrow pedals off a different bike if you don't have an extra pair lying about. If it turns out to be the pedals, then you can decide if you want to fix them or get some new fancy ones or just live with the sound or whatever. The initial swap is just for diagnostic purposes.
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UPDATE. All checked, problem seem to be the BB.
It is or loose ot worn out.
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Hi CT!
Thanks so much for the followup; this thread will help others in similar straits in future.
Glad to hear all is sorted for you.
Best,
Dan.
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I had this noise as well.
It turned out to be one of the points Dan had flagged.
Loose chain ring bolts.
I had removed it to do a proper clean.
When the noise appeared I was stumped.
But Fans suggestion helped me track it down.
I had not tightened all of the bolts up completely.
Once done, problem solved.
They were only slightly loose.
Not even really loose. But enought to creak.
Matt
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I know crazytraveller's issue has been resolved, which is great news, but just to add another possible factor from my own recent experience, you can get a crunchy sound when the chain is too loose, as well. My relatively new Nomad that has been getting noisier, especially in high gear and standing situations. When I put it up on the stand, I found that as I rode, each link was momentarily slightly holding up on the bottom of the chain ring, then falling away. The chain was loose, but not enough to fall off. The chain line appears spot on as well.
I measured T1-T2, which was 76mm (difference of distances between inside of chain when spread out vs when squeezed together at the midpoint - see the manual). Thorn recommends about 40mm, and no more than 60mm. I tightened the chain ( first time time since building the bike), and the "problem" was solved.
YMMV, but it's worth mentioning. BTW, now that I have made this first adjustment, I don't expect to have to touch it for several thousand km. Time will tell, but it feels like it will be a long time (and a new chain) before I am running over the same dimples on the BB.
PS - I am running 38x16, so I will watch the link alignment, as was mentioned earlier...
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Joining an old thread because I now suffer similar symptoms and I can't track down the cause.
Chain is well adjusted and sparkling clean and teflon dry lubed.
The chainwheel bolts needed tightening but no improvement thereafter.
Eccentric BB bolts tight.
Chainwheel and rear sprocket clean.
The rear sprocket is showing some wear with a bit of sharks fin showing but nowhere near pointy yet.
Pedals removed, checked, regreased and refitted tight.
Each chain link checked for stiffness.
Still I have the noise and slight vibration.
BB? It has only done about 13,000 km so I would doubt it?
I'm a bit stumped and rather disheartened.
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Hi rafiki, you don't say whether it is a tick or a gravelly sound, if the former try removing the cranks, greasing and refitting. If gravelly then it is likely to be transmission or bb. If it appears to be coming from the hub when under load tr backing off the skewer tension slightly.
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there u go so much for changing things that dont need changing BB, next problem the rohloff will probably explode leaving you stranded.
if you went for a shimano bb you would never have this problem.and if you did a tenner would have you back cycling in silence.and thats a fact..
just saying now don't go shooting me. ;D
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Did the noise start suddenly one day, or has it been building up slowly over time?
Is it a creak or rumble that comes and goes once per crank revolution or is it more steady than that?
The way sound runs around a metal bike frame, these things are notoriously difficult to track! Don't be too discouraged!
You can always just pull the chain off the chainring and spin the cranks just to check if the BB itself is too messed up. Of course a BB problem might manifest only under load. But it seems very unlikely and is surely the last sort of fix you want to try! Be patient, try little tests, you'll figure it out!
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Another classic is the sharp noise from your pedal arm, and an easy fix. Thats if its a taper.
Remove the arm clean with a bit of emery cloth/sandpaper, get all the grease off with turps, let dry and reinstall.
Tighten, give it a light tap with a bit of timber, and check again so its tight.
Many people put grease on. This is one place you want dry and clean.
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Thanks all.
It is a gravelly sound.
It happens under load, otherwise she just sings along!
It came on quite suddenly. Repaired a puncture and put the wheel back on. Since then have taken it off, re-seated it and checked skewer not overtight.
Shimano bottom bracket BB-ES25-AK
Any supplementary thoughts?
Brian.
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The gravel sound sure brings to mind a mismatch between chain and chainring and/or sprocket.
One wild idea: suppose the sprocket and chain both have an even number of teeth/links, or divisible by 3 or whatever. Maybe they've worn together in some repeating pattern. Then you put the chain back on but didn't line the pattern back up.
Maybe try removing the wheel again and just move the chain one step up on the sprocket?
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Thanks. I'll give it a go in the morning. Just did a 40 km ride on my trusty old lady - a 22 year old Dawes Mean Street. Absolutely silent. :)
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Hah HA there u go you cant beat tried and tested gear works every time..
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True, but I'd still like to get my Sterling working properly again. ;)
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AH just winding you lads up. if as you say its a grinding noise it has to be bearing problem either in the pedals or BB.mind u try degreasing the chain wash it in warm soapy water and relube .
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Not so much a grinding noise as a gravelly noise really.
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has to be bearings.
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I go for chain n sprockets.
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Just returned from a 53km ride after moving the chain along one link. BINGO! Smooth as silk under any load. On the first climb I kept her in the highest gear I could and stood up. My heart missed a beat when there seemed to be an irregular ticking sound - until I realised it was some road tar bits being thrown up into the mudguard!
Problem solved! Thanks to everyone who has contributed their thoughts and suggestions.
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emm thats a new one on me .great your sorted ;)
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Wonderful news, Brian! So glad you're sorted. Thanks for the followup; it is bound to help others as well.
Best,
Dan.
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Take a bow JimK! Glad you are sorted.
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Wow, fantastic! That was a shot in the dark, but sometimes the target gets hit!
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;)clever boy.
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It has left me with my ongoing quandary each day: which bike to take! My lovely old lady the 24 year old Dawes or the younger Sterling. I happened to mention that to my wife and then, inadvisedly, said that it's easier with two lovely women; with bikes you can only take them out one at a time! ;D I had to duck.
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You're being modest, Jim -- inspired stuff! Now if only I can remember this...
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Just returned from a 53km ride after moving the chain along one link. BINGO! Smooth as silk under any load. On the first climb I kept her in the highest gear I could and stood up. My heart missed a beat when there seemed to be an irregular ticking sound - until I realised it was some road tar bits being thrown up into the mudguard!
Problem solved! Thanks to everyone who has contributed their thoughts and suggestions.
Been there, done that. Happens more if you run even/even i think as I do (40*16)
Some will mark the sprocket on a tooth that has a chain inner (as opposed to outer) link on it. Someone here came up with that smart idea.