Left crank arm fell off a week after maintenence tuneup
08-06-14, 04:51 AM
#26
Senior Member
Hmmm. Every bike mechanic I've ever encountered has hands covered in old grease. Let me wash those off, pull out the keyboard/iPad/whatever, get it dirty in the process and look up the spec on something I've done every day for the last 20 years, all while the shop owner is asking me to look at this guy's kid's bike.
08-06-14, 06:02 AM
#27
ot.net slave
Join Date: Feb 2006
Location: Canberra, Australia
Posts: 571
Bikes: Salsa mtb * 3, Intense mtb * 1, Abeni SS rd * 1, Salsa road/touring * 2, Trek Damn one * 1, Vintage/projects * many
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Hmmm. Every bike mechanic I've ever encountered has hands covered in old grease. Let me wash those off, pull out the keyboard/iPad/whatever, get it dirty in the process and look up the spec on something I've done every day for the last 20 years, all while the shop owner is asking me to look at this guy's kid's bike.
If we had constant broken fasteners or crushed parts, or parts falling off or rattling, I might consider using the torque wrenches for more common stuff. As it is, I use them for things like pivot bolts which are not necessarily intuitive or done frequently.
The Bontrager/Ritchey Torque Key type things though, we use all the time. They're a very handy 5.5nM preset for most lightweight stem bolts.
- Joel
08-06-14, 07:16 AM
#28
Let your bike be the tool
Join Date: Jun 2006
Location: NC/SC border
Posts: 938
Bikes: '66 Raleigh Carlton, '70 Ron Cooper, '95 Bianchi CD'I, Zonal Frame with Xenon gruppo, Carbon Frame with Record Gruppo, Columbia Twosome, Terry Classic, Bianchi SX, Gravity SS/FG
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 336 Post(s)
Liked 313 Times
in
193 Posts
Under-torqued crank bolts are the sickness as unto death?
__________________
Never try to teach a pig to sing...
Never try to teach a pig to sing...
08-06-14, 08:20 AM
#30
Mechanic/Tourist
Greasing the spindle can lead to overtightening. I have never used anything more than the residual "mechanic's hand lotion" on my fingers on a spindle. It is just as likely that they left some contamination such as rust scale on the mating surfaces. I always clean the spindle and crank hole with fine steel wool when overhauling an crankset that shows some dirt and corrosion.
08-06-14, 10:48 AM
#31
Senior Member
Join Date: May 2010
Location: midwest
Posts: 2,528
Bikes: 2018 Roubaix Expert Di2, 2016 Diverge Expert X1
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 482 Post(s)
Liked 151 Times
in
105 Posts
Greasing the spindle can lead to overtightening. I have never used anything more than the residual "mechanic's hand lotion" on my fingers on a spindle. It is just as likely that they left some contamination such as rust scale on the mating surfaces. I always clean the spindle and crank hole with fine steel wool when overhauling an crankset that shows some dirt and corrosion.
Without the light coating of grease the mating surfaces seem to build tension under load, then slip giving clicking noises. Plus these are two dissimilar surfaces: aluminum and steel.
I wouldn't think it good to remove bearing surface with steel wool, no matter how fine.
Last edited by GeneO; 08-06-14 at 10:58 AM.
08-06-14, 11:08 AM
#32
Mechanic/Tourist
My error - we oldsters often automatically assume square taper spindle. Greasing the spindle on a BB30 is correct.
08-06-14, 11:42 AM
#33
Member
Join Date: Jul 2014
Location: Vermont
Posts: 43
Bikes: 80s Ciocc Designer '84 Rival, All City Space Horse w/mostly Velo Orange Grand Crux touring parts, steel mtb with mechanic scavenged group, '73 Raleigh Super Course w/braze on canti bosses and a 700c Sturmey Archer 3 speed wheelset
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I gave them a call yesterday and left a message detailing my situation (they were closed) with a callback number. I was surprised that they did not attempt to call back.
I called them again today and spoke to the guy who I consulted with when I brought the bike in. He was totally nonchalant about the whole thing. I tried to be polite and non-accusatory.
"So right after the maintenance the left crank arm fell right off while I was riding."
"Ok?" <silence>
"Yeah, well, you guys put a bottom bracket on it and then a component that connects to the bottom bracket falls off"
"Bring it in."
"Well, I was wondering what you thought about it" (I'm a few towns away so I wanted to get some info on what they might do before I took the long trip up... maybe a discount, or a free fix, or a possible explanation, or an apology?)
"I can't do anything without looking at the bike."
"Well, do you think it is a bit unusual that a week after the maintenance the crank arm falls off?"
"Bring it in."
"Uh, ok. Thanks, bye"
<click>
I was blown away by his snobbishness. He definitely doesn't care about his customer's satisfaction. He won't say anything until I drive the lengthy trip up to the shop so he can "look at it". Well I already paid him to "look at it". The phone call telegraphed his disposition towards me and based on that I think any hope of repairing this situation without additional cost to me is null. Curiosity makes me want to head up there just so I can pry at him and see what he says back. If I want to get riding again I feel I should find a new shop. From the posts here it sounds like possibly the crank arm slot is damaged if it loosened enough to fall off. Anyway, I need a trusting set of eyes and these guys aren't it. It's almost too humiliating to go back in that store.
Sounds like it's a trip to a new bike shop and time to write some consumer reviews.
I called them again today and spoke to the guy who I consulted with when I brought the bike in. He was totally nonchalant about the whole thing. I tried to be polite and non-accusatory.
"So right after the maintenance the left crank arm fell right off while I was riding."
"Ok?" <silence>
"Yeah, well, you guys put a bottom bracket on it and then a component that connects to the bottom bracket falls off"
"Bring it in."
"Well, I was wondering what you thought about it" (I'm a few towns away so I wanted to get some info on what they might do before I took the long trip up... maybe a discount, or a free fix, or a possible explanation, or an apology?)
"I can't do anything without looking at the bike."
"Well, do you think it is a bit unusual that a week after the maintenance the crank arm falls off?"
"Bring it in."
"Uh, ok. Thanks, bye"
<click>
I was blown away by his snobbishness. He definitely doesn't care about his customer's satisfaction. He won't say anything until I drive the lengthy trip up to the shop so he can "look at it". Well I already paid him to "look at it". The phone call telegraphed his disposition towards me and based on that I think any hope of repairing this situation without additional cost to me is null. Curiosity makes me want to head up there just so I can pry at him and see what he says back. If I want to get riding again I feel I should find a new shop. From the posts here it sounds like possibly the crank arm slot is damaged if it loosened enough to fall off. Anyway, I need a trusting set of eyes and these guys aren't it. It's almost too humiliating to go back in that store.
Sounds like it's a trip to a new bike shop and time to write some consumer reviews.
Now, why did it happen. Could be the crank arm was already getting pretty rounded out -- square taper crank arms, if their taken off and put on repeatedly do eventually round and then refuse to stay on. Could be as simple as the mechanic forgetting to put a wrench on it -- often times to tighten that bolt, you put it in then spin the cranks while holding with your fingers and that tightens the bolt down finger tight. Then you put a wrench on it and really tighten it down. It's of course possible that he got interrupted at exactly that moment and then forgot to actually put a wrench on it.
What would I do? I'd go back that store. If it is stripped, they should replace the crank. If it isn't, they won't charge you for checking it out and putting it on, and if they're rude about it, then don't go back.
08-06-14, 11:43 AM
#34
You gonna eat that?
Part of being a professional is knowing which are the critical torques that need to be measured.
__________________
I stop for people / whose right of way I honor / but not for no one.
Originally Posted by bragi 
"However, it's never a good idea to overgeneralize."
I stop for people / whose right of way I honor / but not for no one.
Originally Posted by bragi "However, it's never a good idea to overgeneralize."
08-06-14, 11:43 AM
#35
Member
Join Date: Jul 2014
Location: Vermont
Posts: 43
Bikes: 80s Ciocc Designer '84 Rival, All City Space Horse w/mostly Velo Orange Grand Crux touring parts, steel mtb with mechanic scavenged group, '73 Raleigh Super Course w/braze on canti bosses and a 700c Sturmey Archer 3 speed wheelset
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
08-06-14, 01:47 PM
#37
working on my sandal tan
Join Date: Aug 2011
Location: CID
Posts: 22,627
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)
Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3870 Post(s)
Liked 2,563 Times
in
1,577 Posts
Why bring up greased (or not) spindles in this thread? A square-taper crank gets rounded out because it is ridden while loose, and that shouldn't happen if it was "overtightened", right? 
08-06-14, 01:51 PM
#38
Senior Member
08-06-14, 01:52 PM
#39
Wheel Builder
Join Date: Jun 2014
Location: Toronto, Ontario
Posts: 148
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 17 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
The use of torque wrenchws on bicycles is a relatively new phenomenon. Not counting a fringe element that confuses bicycles with space vehicles, nobody started using torque wrenches until the advent of carbon parts. That's after the square taper crank was already being phased out on better bikes. In the heyday of Sq. taper, millions upon millions of these were installed and maintained by both pros and amateurs with no serious issues. (Yes, some did work loose, but the numbers are small and consistent with other mechanical issues).
So, maybe younger mechanics that were never properly trained might not know how to properly torque a crank bolt, but the vast majority of mechanics, pro and not, can and do install these reliably time after time.
It's not a question of tools, it's a question of skill, and more important, craftsmanship and care.
BTW- if we continue to foster the ridiculous notion that torque specs have to be looked up for every mundane job, the cost of bicycle repair will increase beyond the reach of most of the public, and we'll be moving to throwaway bicycles.
So, maybe younger mechanics that were never properly trained might not know how to properly torque a crank bolt, but the vast majority of mechanics, pro and not, can and do install these reliably time after time.
It's not a question of tools, it's a question of skill, and more important, craftsmanship and care.
BTW- if we continue to foster the ridiculous notion that torque specs have to be looked up for every mundane job, the cost of bicycle repair will increase beyond the reach of most of the public, and we'll be moving to throwaway bicycles.
I use torque wrenches a lot, but I do agree with FB.
If you ever worked in a shop that employee 6 mechanics with 10+ tune-ups per day for each of them. You will know the torque specs on most of the stuff.
Once, me and my co-worker find out that our torque wrench needed a calibration because we felt it was off. And we were right. If we let the junior mech. to work on a high-end carbon bike with the wrench, it could've been a mess.
If you rely on tools too much, you have no backup.
08-06-14, 02:21 PM
#40
Member
Join Date: Jul 2014
Location: Vermont
Posts: 43
Bikes: 80s Ciocc Designer '84 Rival, All City Space Horse w/mostly Velo Orange Grand Crux touring parts, steel mtb with mechanic scavenged group, '73 Raleigh Super Course w/braze on canti bosses and a 700c Sturmey Archer 3 speed wheelset
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
If you over tighten a crank on a square spindle you're pushing the crank further onto the taper, thereby widening the the hole the spindle goes through. If you take a crank on and off enough times, eventually it may become sufficiently worn enough that it won't ever be tight enough, then it will loosen and round out. Greasing the spindle could result in over tightening. This was the thinking in the shops I worked in about 15 years ago. Back then torque wrenches were rarely, if ever, used.
08-06-14, 03:02 PM
#41
working on my sandal tan
Join Date: Aug 2011
Location: CID
Posts: 22,627
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)
Mentioned: 98 Post(s)
Tagged: 0 Thread(s)
Quoted: 3870 Post(s)
Liked 2,563 Times
in
1,577 Posts
If you over tighten a crank on a square spindle you're pushing the crank further onto the taper, thereby widening the the hole the spindle goes through. If you take a crank on and off enough times, eventually it may become sufficiently worn enough that it won't ever be tight enough, then it will loosen and round out. Greasing the spindle could result in over tightening. This was the thinking in the shops I worked in about 15 years ago. Back then torque wrenches were rarely, if ever, used.
08-06-14, 05:14 PM
#42
Senior Member
Join Date: May 2010
Location: midwest
Posts: 2,528
Bikes: 2018 Roubaix Expert Di2, 2016 Diverge Expert X1
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 482 Post(s)
Liked 151 Times
in
105 Posts
EDIT: And I am talking, I didn't read your last post above before I posted this. Sorry didn't mean to derail this - shouldn't have used greased and spindle together in a sentence LOL.
Last edited by GeneO; 08-06-14 at 05:20 PM.
08-06-14, 07:19 PM
#43
Banned
Join Date: Apr 2010
Location: Lincoln Ne
Posts: 9,924
Bikes: RANS Stratus TerraTrike Tour II
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 3352 Post(s)
Liked 1,056 Times
in
635 Posts
retro +1
Crank arms are a really good place to use a torque wrench. It simply is the right tool for a professiona job.
Under torque and the arm falls off like it did for the thread creator. Too tight and it can ruin the arm for all time.
Crank arms are a really good place to use a torque wrench. It simply is the right tool for a professiona job.
Under torque and the arm falls off like it did for the thread creator. Too tight and it can ruin the arm for all time.
08-07-14, 04:55 PM
#44
Pedal Pusher/Pundit
Join Date: Jul 2012
Location: Hutchinson/Minneapolis, MN
Posts: 420
Bikes: Motobecane Jubilee
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I would take it back and see if they fix it to your satisfaction and how they treat you in person. However, the over the phone contact seems to leave a lot to be desired. He should have expressed that he is sorry that you had trouble with your bike but he'd be glad to take a look at it if you brought it in and if the probablem looks like it could have been their fault they'd take care of it. That is Customer Service 101 no matter what sort of business you are in.
I agree with others here that it very well could be that the crank could have been the original problem or perhaps it was improperly installed which caused the crank to fail.
I agree with others here that it very well could be that the crank could have been the original problem or perhaps it was improperly installed which caused the crank to fail.
08-07-14, 05:09 PM
#45
Senior Member
Join Date: May 2008
Location: Zang's Spur, CO
Posts: 9,080
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 3370 Post(s)
Liked 5,491 Times
in
2,844 Posts
Only clamp bolts I've loosened for cable replacement and for parts I'm installing. Everything else was obviously tight enough to stay that way since it was last re-installed or adjusted years ago.
If dialing up a setting takes too long on your torque wrenches get better ones. I'm fond of my Stahlwille wrenches - squeeze the lock, slide the adjusting knob to the appropriate position, and be happy (split-beam wrenches don't require releasing the tension prior to storage as with conventional micrometer wrenches)
If dialing up a setting takes too long on your torque wrenches get better ones. I'm fond of my Stahlwille wrenches - squeeze the lock, slide the adjusting knob to the appropriate position, and be happy (split-beam wrenches don't require releasing the tension prior to storage as with conventional micrometer wrenches)
Did you steal it, or inherit it?
08-07-14, 07:18 PM
#46
Senior Member
Join Date: Apr 2010
Location: Mountain View, CA USA and Golden, CO USA
Posts: 6,341
Bikes: 97 Litespeed, 50-39-30x13-26 10 cogs, Campagnolo Ultrashift, retroreflective rims on SON28/PowerTap hubs
Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 550 Post(s)
Liked 325 Times
in
226 Posts
Otherwise I'd have ordered from Germany where you don't pay the "exotic foreign" markup and Americans don't pay VAT
Vereinigte Staaten von ******* is German for a US shipping address
Manoskop 730
Way less expensive than my last torque wrench malfunction. My HOA made me buy a new garage door after I threw my wrench through it leaving a hole, plus there were the gaskets that needed replacing when the engine came back apart.
Last edited by Drew Eckhardt; 08-07-14 at 07:31 PM.
08-07-14, 07:54 PM
#47
Senior Member
Join Date: May 2011
Location: Midwest
Posts: 369
Bikes: '10 Fuji Cross Comp, '12 Brompton S-Type, '14 All City Mr Pink
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Otherwise I'd have ordered from Germany where you don't pay the "exotic foreign" markup and Americans don't pay VAT
Vereinigte Staaten von ******* is German for a US shipping address
Manoskop 730
Vereinigte Staaten von ******* is German for a US shipping address
Manoskop 730
08-07-14, 09:45 PM
#48
Senior Member
Join Date: Apr 2012
Location: Nor Cal
Posts: 6,016
Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 1814 Post(s)
Likes: 0
Liked 923 Times
in
569 Posts
Doesn't quibbling over torque settings overlook the probability that for the crank to fall off in a week and probably less than 200 miles, it was likely either not tightened at all, or was stripped?
08-08-14, 04:50 AM
#49
Senior Member
Join Date: Jul 2014
Location: SoCal
Posts: 1,331
Bikes: 89 Schwinn 754, 90 Trek 1100, 93 Trek 2300, 94 Trek 1400 (under construction), 94 Trek 930, 97 Trek 1400
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 29 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
If a crankset was checked for damage when the shop replaced the bottom bracket, they should have caught any damage before reinstalling the crankset. If the shop used a torque wrench to tighten the crankarm bolts, they would not have had a reason to strip. If the shop used a torque wrench to tighten the crankarm bolts, they could not have been too loose, and would not have fallen out.
Earlier I read where somebody complained that if he had to look up the torque spec and use a torque wrench a tuneup would take him twice as long to perform. I highly doubt that, and isn't the mechanic's time already being paid for by the customer, who brought the bike in, and accepted the estimate for the cost, agreed to by the shop and the customer? To short the customer by not doing the work being paid for, is unprofessional, and possibly criminal, if neglect causes bodily harm.
