Stripped crank arms = replace Tiagra cranks with 105 or Ultegra, new BB needed?



B

Brad Ford

Guest
Tonight I experienced the joy of riding 15 miles home on one leg. The
ride started out fine, though my left cleat felt like it had a little
more play than usual. Within minutes this feel intensified -- stepping
on the pedal with any force felt like my foot was hanging off of it at
a 45 degree angle below horizontal. I thought maybe a rock had taken a
big chip out of the front of the SPD-SL cleat. I stopped and clicked
out, and the pedal came along for the ride....not good. The threads on
the inside of the left crank were stripped bare, and the pedal was
literally dangling there.

This is my commuting bike, Trek 1200 with Tiagra triple + 9 spd
cassette. I've put about 7000 miles on it.

This unfortunate incident brings up several questions:

1) How did this happen? I use Ultegra spd-sl pedals, and frequently
service them (i.e. once every month to 6 weeks) - cleaning them, then
applying a thin film of grease across the threads before tightening
them back in the ends of the crankarms. Did I overtighten?

2) So now that my left crank is totally useless, I surfed around for a
while and could not find anyone selling replacement Tiagra triple
crankarms or even cranksets. Does anyone know where I can find some?

3) If #2 is not possible, I might consider upgrading to a 105 or
ultegra triple crankset, though I really don't want to pour too much
money into this commuting bike. Is my existing Tiagra BB compatible
with a 105 or Ultegra triple replacement, or would I have to upgrade
the bb as well?

TIA.
 
Brad Ford wrote:
> Tonight I experienced the joy of riding 15 miles home on one leg. The
> ride started out fine, though my left cleat felt like it had a little
> more play than usual. Within minutes this feel intensified -- stepping
> on the pedal with any force felt like my foot was hanging off of it at
> a 45 degree angle below horizontal. I thought maybe a rock had taken a
> big chip out of the front of the SPD-SL cleat. I stopped and clicked
> out, and the pedal came along for the ride....not good. The threads on
> the inside of the left crank were stripped bare, and the pedal was
> literally dangling there.
>
> This is my commuting bike, Trek 1200 with Tiagra triple + 9 spd
> cassette. I've put about 7000 miles on it.
>
> This unfortunate incident brings up several questions:
>
> 1) How did this happen? I use Ultegra spd-sl pedals, and frequently
> service them (i.e. once every month to 6 weeks) - cleaning them, then
> applying a thin film of grease across the threads before tightening
> them back in the ends of the crankarms. Did I overtighten?
>
> 2) So now that my left crank is totally useless, I surfed around for a
> while and could not find anyone selling replacement Tiagra triple
> crankarms or even cranksets. Does anyone know where I can find some?
>
> 3) If #2 is not possible, I might consider upgrading to a 105 or
> ultegra triple crankset, though I really don't want to pour too much
> money into this commuting bike. Is my existing Tiagra BB compatible
> with a 105 or Ultegra triple replacement, or would I have to upgrade
> the bb as well?
>
> TIA.

You have several options, if I understand you correctly. The threads
in the pedal eye of the crank are stripped, correct? I'm more inclined
to think that the threads stripped because you didn't tighten the
pedals enough, as opposed to too much. Use a torque wrench when in
doubt.

1. Go to a good bike shop and ask them to put a 'helicoil' in the
pedal eye. If you're mechanically inclined, and have the right tools,
you can perform this procedure yourself. If done properly the crank
will be better than new.
2. Buy a generic left crank arm, that matches the length of the right
crank arm. Left crank arms from Sugino are generally decent, cheap,
and readily available.
3. Buy a replacement crankset. This may actually be cheaper than any
of the above choices, if you find a crankset on clearance, and if you
don't have to replace the BB. Tiagra cranks use octalink BB, iirc, so
any triple octalink crank ought to suffice, as long as the chain-line
is correct. I routinely see Nashbar clearing out cranksets for around
$45 or so. If you do decide to replace the crankset though, you might
want to consider ditching octalink cranksets altogether (due to the
poor durability of octalink BB bearings) and get a traditional square
taper crankset for commuting purposes. Outboard BBs and corresponding
cranksets get rather expensive, and not everyone is pleased with their
performance.
 
Brad Ford wrote:
> Tonight I experienced the joy of riding 15 miles home on one leg. The
> ride started out fine, though my left cleat felt like it had a little
> more play than usual. Within minutes this feel intensified -- stepping
> on the pedal with any force felt like my foot was hanging off of it at
> a 45 degree angle below horizontal. I thought maybe a rock had taken a
> big chip out of the front of the SPD-SL cleat. I stopped and clicked
> out, and the pedal came along for the ride....not good. The threads on
> the inside of the left crank were stripped bare, and the pedal was
> literally dangling there.
>
> This is my commuting bike, Trek 1200 with Tiagra triple + 9 spd
> cassette. I've put about 7000 miles on it.
>
> This unfortunate incident brings up several questions:
>
> 1) How did this happen? I use Ultegra spd-sl pedals, and frequently
> service them (i.e. once every month to 6 weeks) - cleaning them, then
> applying a thin film of grease across the threads before tightening
> them back in the ends of the crankarms. Did I overtighten?
>
> 2) So now that my left crank is totally useless, I surfed around for a
> while and could not find anyone selling replacement Tiagra triple
> crankarms or even cranksets. Does anyone know where I can find some?

Any bike shop with a Quality account can get you a left arm. As to why
it happened..tough to say unless the pedal was cross threaded in.

>
> 3) If #2 is not possible, I might consider upgrading to a 105 or
> ultegra triple crankset, though I really don't want to pour too much
> money into this commuting bike. Is my existing Tiagra BB compatible
> with a 105 or Ultegra triple replacement, or would I have to upgrade
> the bb as well?

It is compatible if Octalink
>
> TIA.
 
M-gineering wrote:
> Brad Ford wrote:
> > Tonight I experienced the joy of riding 15 miles home on one leg. The
> > ride started out fine, though my left cleat felt like it had a little
> > more play than usual. Within minutes this feel intensified -- stepping
> > on the pedal with any force felt like my foot was hanging off of it at
> > a 45 degree angle below horizontal. I thought maybe a rock had taken a
> > big chip out of the front of the SPD-SL cleat. I stopped and clicked
> > out, and the pedal came along for the ride....not good. The threads on
> > the inside of the left crank were stripped bare, and the pedal was
> > literally dangling there.
> >
> > This is my commuting bike, Trek 1200 with Tiagra triple + 9 spd
> > cassette. I've put about 7000 miles on it.
> >
> > This unfortunate incident brings up several questions:
> >
> > 1) How did this happen? I use Ultegra spd-sl pedals, and frequently
> > service them (i.e. once every month to 6 weeks) - cleaning them, then
> > applying a thin film of grease across the threads before tightening
> > them back in the ends of the crankarms. Did I overtighten?
> >
>
> not tight enough is more likely
>
> > 2) So now that my left crank is totally useless, I surfed around for a
> > while and could not find anyone selling replacement Tiagra triple
> > crankarms or even cranksets. Does anyone know where I can find some?
>
>
> LH cranks are available from Shimano as a spare. Try a bikeshop instead
> of a mailorderhouse. Instead of a new crank they might even be able to
> repair the destroyed thread with an insert
>
>
>
> > 3) If #2 is not possible, I might consider upgrading to a 105 or
> > ultegra triple crankset, though I really don't want to pour too much
> > money into this commuting bike. Is my existing Tiagra BB compatible
> > with a 105 or Ultegra triple replacement,
>
> early Tiagra has a square axle, later ones are the MTB style octalink,
> not compatible with roadcranks

Small point-'MTB' style octalink, for all MTB except XTR were a unique
spline dimension not compatible with anything else. XTR and road
Octalink were the same spline dimensions altho the spindle lengths
varied for road and MTB XTR.
 
On 31 Jan 2006 00:50:49 -0800, "Brad Ford" <[email protected]> wrote:

>Tonight I experienced the joy of riding 15 miles home on one leg. The
>ride started out fine, though my left cleat felt like it had a little
>more play than usual. Within minutes this feel intensified -- stepping
>on the pedal with any force felt like my foot was hanging off of it at
>a 45 degree angle below horizontal. I thought maybe a rock had taken a
>big chip out of the front of the SPD-SL cleat. I stopped and clicked
>out, and the pedal came along for the ride....not good. The threads on
>the inside of the left crank were stripped bare, and the pedal was
>literally dangling there.
>
>This is my commuting bike, Trek 1200 with Tiagra triple + 9 spd
>cassette. I've put about 7000 miles on it.
>
>This unfortunate incident brings up several questions:
>
>1) How did this happen? I use Ultegra spd-sl pedals, and frequently
>service them (i.e. once every month to 6 weeks) - cleaning them, then
>applying a thin film of grease across the threads before tightening
>them back in the ends of the crankarms. Did I overtighten?

Is it really better to fuss with them all the time like that? Or is it that my
maintenance schedule is slack? I check pedals for tightness and knock the gravel
and chunks of wood out and relube with a shot of oil a few times a year. But I
don't see why you'd want to wear out the threads by constantly loosening and
retorquing. Pedals should last many years and crank life in decades that would
add up to dozens or hundreds of loosening - tightening cycles if done your way.

Again, maybe I am woefully ignorant, but it seems that constantly pestering the
threads could lead to just the sort of problem you had. That steel into aluminum
fit just doesn't seem like it was meant to be disturbed all that much.

Any expert opinion on this?

>2) So now that my left crank is totally useless, I surfed around for a
>while and could not find anyone selling replacement Tiagra triple
>crankarms or even cranksets. Does anyone know where I can find some?

LBS will order. Or can install an insert.

Ron


>3) If #2 is not possible, I might consider upgrading to a 105 or
>ultegra triple crankset, though I really don't want to pour too much
>money into this commuting bike. Is my existing Tiagra BB compatible
>with a 105 or Ultegra triple replacement, or would I have to upgrade
>the bb as well?
>
>TIA.
 
Brad Ford wrote:
> Tonight I experienced the joy of riding 15 miles home on one leg. The
> ride started out fine, though my left cleat felt like it had a little
> more play than usual. Within minutes this feel intensified -- stepping
> on the pedal with any force felt like my foot was hanging off of it at
> a 45 degree angle below horizontal. I thought maybe a rock had taken a
> big chip out of the front of the SPD-SL cleat. I stopped and clicked
> out, and the pedal came along for the ride....not good. The threads on
> the inside of the left crank were stripped bare, and the pedal was
> literally dangling there.
>

I was on a group ride out in the boonies when one of our members had the
same thing happen. I thought he was toast as there was no easy way to
call for help.

We ended up wrapping a power bar packaging around the threads of the
pedal and re-inserted it back into the crank.

He finished the rest of the ride that included hills, without problems
to my surprise (not that I wasn't happy for him!)

He ended up putting in a helicoil that lasted for a few years.

Definitely one of those things that I'll remember to try when I'm in a
fix. Foil packaging also makes a good tire boots for small holes.
 
"damyth" wrote: (clip) Go to a good bike shop and ask them to put a
'helicoil' in the pedal eye. If you're mechanically inclined, and have the
right tools, you can perform this procedure yourself. If done properly the
crank will be better than new. (clip)
^^^^^^^^^^^^^^^^^
All true. A Helicoil is tougher and more durable than any aluminum thread.
It is extremely unlikely that you would have the right tools and still be
asking this question. And the tools ain't cheap. You need a special size
drill bit, which in this instance will probably be too big to fit in your
pistol drill. Then you need a special tap. And then an insertion tool.
You could probably replace the crank set for less money than it would cost
to buy all that stuff. Let your LBS do it.
 
Leo Lichtman wrote:
> "damyth" wrote: (clip) Go to a good bike shop and ask them to put a
> 'helicoil' in the pedal eye. If you're mechanically inclined, and have the
> right tools, you can perform this procedure yourself. If done properly the
> crank will be better than new. (clip)
> ^^^^^^^^^^^^^^^^^
> All true. A Helicoil is tougher and more durable than any aluminum thread.

How can the Helicoil be better than or more durable than the original
crank threading? Doesn't the Helicoil thread into the aluminum crank
itself? Therefore, at best, at best, it can only be as durable as the
original, not better than new or more durable.


> It is extremely unlikely that you would have the right tools and still be
> asking this question. And the tools ain't cheap. You need a special size
> drill bit, which in this instance will probably be too big to fit in your
> pistol drill. Then you need a special tap. And then an insertion tool.
> You could probably replace the crank set for less money than it would cost
> to buy all that stuff. Let your LBS do it.
 
"M-gineering" wrote: larger diameter, and no steel moving over aluminium
during installation
^^^^^^^^^^^^^^^
One more thing: the original thread had to have some clearance to allow it
to go together without binding. This clearance reduces the amount of
contact surface, and allows a little side shake if the thread ever starts to
loosen. This is very bad on a pedal/crand thread, because of the severe
side loads, and it is what usually causes failure. A Helicoil is a
stainless steel coil spring, deliberately made slightly larger than the
tapped thread that is to receive it. The insertion tool is designed to
twist the insert, so that its diameter is reduced during insertion. As soon
as the insertion tool is removed, the coil springs back to fit tightly
against the aluminum thread. This internal preload keeps the insert in
place--if the pedal should start to loosen, it could back out, but it will
not take the insert with it. Also, if the pedal should start to loosen, the
"action" will be between a tough stainless steel insert and the pedal shaft
(steel, usually) and not between the pedal shaft and a vulnerable, fine
pitch aluminum thread.
 
Brad Ford wrote:
> Tonight I experienced the joy of riding 15 miles home on one leg. The
> ride started out fine, though my left cleat felt like it had a little
> more play than usual. Within minutes this feel intensified -- stepping
> on the pedal with any force felt like my foot was hanging off of it at
> a 45 degree angle below horizontal. I thought maybe a rock had taken a
> big chip out of the front of the SPD-SL cleat. I stopped and clicked
> out, and the pedal came along for the ride....not good. The threads on
> the inside of the left crank were stripped bare, and the pedal was
> literally dangling there.
>
> This is my commuting bike, Trek 1200 with Tiagra triple + 9 spd
> cassette. I've put about 7000 miles on it.
>
> This unfortunate incident brings up several questions:
>
> 1) How did this happen? I use Ultegra spd-sl pedals, and frequently
> service them (i.e. once every month to 6 weeks) - cleaning them, then
> applying a thin film of grease across the threads before tightening
> them back in the ends of the crankarms. Did I overtighten?
>

not tight enough is more likely

> 2) So now that my left crank is totally useless, I surfed around for a
> while and could not find anyone selling replacement Tiagra triple
> crankarms or even cranksets. Does anyone know where I can find some?


LH cranks are available from Shimano as a spare. Try a bikeshop instead
of a mailorderhouse. Instead of a new crank they might even be able to
repair the destroyed thread with an insert



> 3) If #2 is not possible, I might consider upgrading to a 105 or
> ultegra triple crankset, though I really don't want to pour too much
> money into this commuting bike. Is my existing Tiagra BB compatible
> with a 105 or Ultegra triple replacement,

early Tiagra has a square axle, later ones are the MTB style octalink,
not compatible with roadcranks

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl
 
In article
<[email protected]>,
[email protected] wrote:

> Leo Lichtman wrote:
> > "damyth" wrote: (clip) Go to a good bike shop and ask them to put a
> > 'helicoil' in the pedal eye. If you're mechanically inclined, and have the
> > right tools, you can perform this procedure yourself. If done properly the
> > crank will be better than new. (clip)
> > ^^^^^^^^^^^^^^^^^
> > All true. A Helicoil is tougher and more durable than any aluminum thread.
>
> How can the Helicoil be better than or more durable than the original
> crank threading? Doesn't the Helicoil thread into the aluminum crank
> itself? Therefore, at best, at best, it can only be as durable as the
> original, not better than new or more durable.

The new threads are steel. More difficult to strip steel
threads. The steel on aluminum interface is a press fit,
not a sloppy thread. The pedal spindle is steel. The
fretting is steel on steel, and so the wear is slower than
steel on aluminum.

--
Michael Press
 
Qui si parla Campagnolo wrote:

>
> Small point-'MTB' style octalink, for all MTB except XTR were a unique
> spline dimension not compatible with anything else. XTR and road
> Octalink were the same spline dimensions altho the spindle lengths
> varied for road and MTB XTR.
>


'road (first)spline' : 5500. 6600 7700 series, XTR
'MTB' (improved for high load or cast cranks), XT, LX, Deore, Tiagra

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl
 
On 2006-01-31, Brian S <[email protected]> wrote:

> I was on a group ride out in the boonies when one of our members had the
> same thing happen. I thought he was toast as there was no easy way to
> call for help.
>
> We ended up wrapping a power bar packaging around the threads of the
> pedal and re-inserted it back into the crank.
>
> He finished the rest of the ride that included hills, without problems
> to my surprise (not that I wasn't happy for him!)
>
> He ended up putting in a helicoil that lasted for a few years.
>
> Definitely one of those things that I'll remember to try when I'm in a
> fix. Foil packaging also makes a good tire boots for small holes.

As do dollar bills. The paper used for currency is very tough and resists
pressure nicely.

--

John ([email protected])
 
RonSonic wrote:

>...But I don't see why you'd want to wear out the threads by constantly
>loosening and retorquing...

Hi Brad

I don't know if your method is best or not. (Just because the pedal eye
failed doesn't necessarily mean that it was your practice that caused
it.) But I only remove a pedal when necessary. such as to overhaul or
change to another bike.
I always carefully clean the threads, both ID & OD, slather on
Anti-seize, (I buy a largish can w/ a brush) screw em back in place, w/
enough torque to know they're in place. (One place I don't measure
torque, don't have thin crows feet, never needed them.) Wipe off the
excess Anti-seize. And "Go Ride". Some times I've had pedals sit in a
crank for years not being ridden for one reason or another. (For over
20 yrs, I've owned btn. 4 & 8 bikes @ any given time) I've never had a
problem removing a pedal that I have installed w/ Anti-seize, that a
Park PW-3 couldn't solve, & never striped out a crank. I attribute this
to the careful cleaning & anit-seize application. Many written bike
maintenance instructions say to use plain old grease for this
application. I use cheap lithium grease in a lot of places, but this is
not one of them. I've read that for some reason pedals should be
tightened w/ a torque wrench to ~30 ft. lbs. (Off the top of my head).
I've yet to understand this. If the pedaling motion tends to tighten
the pedal spindle, then why tighten it beyond snug to begin with?

If it were me, I'd repair w/ a helical, unless I wanted an excuse to
upgrade the entire crank set, But you could be entering a quagmire of
compatibility & chain line issues. If you do up grade make certain the
new crank is purchased & installed at a good bike shop w/ someone who
knows what they are doing. Not that it's rocket science, but there are
a few traps to be fallen into.

I'd either repair or up grade, not remove the pedals more often than
necessary, and trust anti-seize to work.

Hope this helps, John
 
I've had ulterior motives in taking the pedals off every 6 weeks. Over
Christmas vacation I did it in order to take my pedals with me and ride
my brother-in-law's Cannondale Ironman Tri-bike all over Arizona. More
recently I did it to road-test a Madone 5.9 SL.

Believe me, I wouldn't be so diligent otherwise. ;-)
 
Thanks all for your comments and suggestions. A nice fellow from
Re-Cyclery in San Rafael had a 170 mm Tiagra left crank he could sell
me very cheap. Beats the heck out of laying down $$$ on a new
crankset.

I'll save that dough for the dream bike...

Cheers!
 
"Brad Ford" I've had ulterior motives in taking the pedals off every 6
weeks. (clip)
^^^^^^^^^^^^^^^^
Go back to Recyclery and look in the room up front. They have BOXES of used
pedals for very reasonable prices. You could probably find a pretty good
pair to save yourself a lot of work, wear and tear.

And, YES! Aren't they great people to deal with? On top of that, the money
you spend there goes to a very worthwhile cause. They take inner city kids
for mountain bike rides. They also train kids to repair bikes, and often
this leads to employment in some of the local bike shops.
 
[email protected] wrote:
> Leo Lichtman wrote:
>
>>"damyth" wrote: (clip) Go to a good bike shop and ask them to put a
>>'helicoil' in the pedal eye. If you're mechanically inclined, and have the
>>right tools, you can perform this procedure yourself. If done properly the
>>crank will be better than new. (clip)
>>^^^^^^^^^^^^^^^^^
>>All true. A Helicoil is tougher and more durable than any aluminum thread.
>
>
> How can the Helicoil be better than or more durable than the original
> crank threading? Doesn't the Helicoil thread into the aluminum crank
> itself? Therefore, at best, at best, it can only be as durable as the
> original, not better than new or more durable.
>
larger diameter, and no steel moving over aluminium during installation

--
---
Marten Gerritsen

INFOapestaartjeM-GINEERINGpuntNL
www.m-gineering.nl
 
On Wed, 01 Feb 2006 05:45:51 GMT, "Leo Lichtman"
<[email protected]> wrote:

>
>"Brad Ford" I've had ulterior motives in taking the pedals off every 6
>weeks. (clip)
>^^^^^^^^^^^^^^^^
>Go back to Recyclery and look in the room up front. They have BOXES of used
>pedals for very reasonable prices. You could probably find a pretty good
>pair to save yourself a lot of work, wear and tear.
>
>And, YES! Aren't they great people to deal with? On top of that, the money
>you spend there goes to a very worthwhile cause. They take inner city kids
>for mountain bike rides. They also train kids to repair bikes, and often
>this leads to employment in some of the local bike shops.
>

Do you think that he will find a used set of SPD-SL? Probably not.


Life is Good!
Jeff
 
On 2006-01-31, Leo Lichtman <[email protected]> wrote:

> "damyth" wrote: (clip) Go to a good bike shop and ask them to put a
> 'helicoil' in the pedal eye. If you're mechanically inclined, and have the
> right tools, you can perform this procedure yourself. If done properly the
> crank will be better than new. (clip)

> All true. A Helicoil is tougher and more durable than any aluminum thread.
> It is extremely unlikely that you would have the right tools and still be
> asking this question. And the tools ain't cheap. You need a special size
> drill bit, which in this instance will probably be too big to fit in your
> pistol drill. Then you need a special tap. And then an insertion tool.
> You could probably replace the crank set for less money than it would cost
> to buy all that stuff. Let your LBS do it.

The OP will need a left-hand thread helicoil for his left crank arm as
well.

--

John ([email protected])
 
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