zymphad

Here is a solution I went with for those who find out it's been stripped out too much for helicoil or if helicoil cost more than you are willing to pay.

I went to a local machine shop and had them drill out the pedal itself and used a washer on the back of the crank to attach the pedal. It's been going strong and near permanent. Just letting others know so you don't have to throw out your crank, especially if it's a nice crank. I was nearly in tears when pedal fell off my 105 crank. This fix was so cheap. I had two LBS wouldn't touch it since they didn't want to be liable for the crank, was told if it was a cheap crank they would... Yay for local machine shop

buffalowings

Nice solution! Although it would be way better to avoid stripping the crank in the first place..

zymphad

I completely agree!

3alarmer 

...could you possibly explain this for me in other words and phrases ?
Because I've read it three times and still can't visualize what you've done.

We do this a lot at the bike coop, and if there's a cheaper alternative,
it would help some of our patrons a great deal. thanks.

zymphad

Machine shop drilled a hole in the back of the pedal, the steel part. Tapped and then used a washer to attach the pedal. It's very stiff and working well. No flex at all.

3alarmer 

...thx.

2 wheeler

An ounce of prevention is worth a pound of cure....

(make sure your pedals are tight)

f4rrest

I still don't get it. Used a washer to attach the pedal? Do you mean a bolt through a washer (from the back of the crank) into the new pedal threads?

dralways

Translation = we need video

znomit

MS Paint will do.

I'm stuck at which end of the pedal is the back.

Campag4life

OP...your technical description is seriously lacking. No idea what you did. Drill a hole in the pedal? With standard pedal spindle thread, a washer and nut won't work because there will be inadequate thread engagement....thread depth on a pedal is about the same as the crank arm thickness. Also, if you cut a counterbore on the inboard side of the crank arm to create clearance for a nut, then you dramatically weaken the spindle attachment to the arm. I wouldn't ride it.
Helicoil or...aluminum weld, redrill/tap or new crank are the safe solutions.

OldTryGuy

Drill into pedal threaded end and tap pedal. Install pedal in stripped crank arm. Bolt/washer on inside of crank then thread into pedal. Tighten bolt.???? maybe this

NOTE-good idea to add a lock washer between bolt head and washer and/or some Loctite.

rpenmanparker 

He used a large head bolt and washer (to catch on the back side of the crank arm) that threaded into the drilled and tapped pedal spindle. For example if we are talking about the right hand pedal, the bolt points from the back of the crank arm to the right side of the bike INTO THE PEDAL SPINDLE. If the pedal spindle is too long and goes through to the back side of the crank, it could be necessary to grind if off shorter so the bolt can draw it tight into the crank. Only question I have is how should you manage this on the left side, with right or left handed threads to correspond to how that pedal is normally attached to the bike. If left handed threads, it might be hard to find someone able to do that and also hard to find the necessary bolt. I suppose you could just try normal right handed threads and bolt and use Loctite.

Years ago I fixed an aluminum crank arm by drilling it out to a larger hole and threading in a solid disk to fill the hole. The disk was then drilled and tapped to the correct diameter and thread for the pedal to attach normally. That was very elegant and nearly undetectable, but it was expensive to have done and wouldn't work with carbon fiber. In that case OP's solution is helpful.

Campag4life

Belief you and Robert are right about what the OP did. A ridiculous kluge for the simple fact that drilling/tapping a female hole in the threaded end of pedal spindle not only weakens the spindle dramatically in cantilever/vertical loading but an undersized bolt threaded into the threaded spindle is axially weak as well. So the design is severely compromised.
The notion of a precipitous failure when sprinting out of the saddle comes to mind. Dangerous.

99Klein 

But 105 cranks are really pretty cheap. Much cheaper than a Dr. visit. Why not replace it? Purchase a used one or a lessor quality crank? Not something I would ride but I'm old and have done my share of foolish things too.

Campag4life

Of course. Even under ideal circumstances a pedal can snap off. Drilling a spindle? Whoops.
We all learn from our mistakes...provided avoid the big ones and live.

rpenmanparker 

In the case of the crank I fixed by filling with a solid, threaded disk and re-drilling the hole the crank was French threaded and vintage with nostalgic (not me, but a friend) value. So the repair made some sense. And the job was extremely elegant. Not only that but the shop did the work as a favor by a friend, no charge. That is tough to beat.

R1lee

Epoxy

zymphad

Whoa, didn't realize it was confusing, thought I described it clearly. I'm not technical with tools etc, that's why I brought it to a machine shop. It's a really simple, very simple fix. Nothing complicated.
- Also this shop installs hundreds of helicoils a week and have helicoils in all sizes, except the 9/16-20. For helicoil 9-16-20 doesn't exist, it's not in their catalog, have to go with some bike specific recoil. Shop laughed, asked who decided to use 9/16-20 and thought this was a good idea? Suffice to say, they think bike industry are dicks.
- Also I didn't mean for this fix to be say, good for racing. I don't have any experience with racing and what kind of stress it would put the pedal through, but I ride about 20-30 miles a day + commute to work and this fix has been solid, no flex at all.
- Was told I would not be able to unscrew this easily by hand.

Only thing I worried about was clearance between crank and chain and for this job it is good. Never hits chain, on the lowest gear, which is also a non-issue since I'm not strong enough rider to be on that gear. 34/50 - 11-28 gearing.

clasher

Unior threaded inserts are made in this size but I have no idea about how they compare to helicoils. Still, that's a neat fix.

rpenmanparker 

OP, please take no offense, because we really are trying to be helpful. It is that two important technical terms that you have used in your posts are wrong. You said you used a washer to attach the pedal, but you meant a bolt (with washer or not). That's a big and confusing difference. The you said you are not strong enough to pedal the lowest gear, but you must have meant the highest gear, the one using the smallest rear cog. Lower gears are easier to pedal, higher gears are harder. Just trying to help you out.

zymphad

Thanks, I don't take offense, this is a great forum.

FYI for others wondering, those marks on the washer and crank are not scrapes. It's salt. Roads are very salty. Been wiping down bike for 20 minutes everytime I get home past week.

2 wheeler

Agreed.

I'm sure that the OP is proud this "fix", but there are serious and dangerous issues with the execution that could very well result in catastrophic failure.

I wouldn't ride out of the saddle on a bike with a mod like that.

Brian Ratliff

Just make sure it stays tight. Every time you stomp the pedals, you are putting body weight plus shock load on that pedal. That's a lot of force on a cantilevered structure. Because of the rotating action of the pedals, the interface will be under a rotating load which might cause problems with the bolt trying to loosen over time and material wear as the pedal shaft tries to rotate with respect to the crank arm. Hopefully the bolt is stainless.

I would seriously put an Allen key to check tension before and after each ride until you replace the crankset. You have also weakened the spindle of the pedal, so be sure to check periodically for bending. I would not view this fix as permanent, but merely as a measure allowing you to ride for a few months until you can find a new crankset at a good price.

Brian Ratliff

I don't think any failure from this fix will be catastrophic unless the OP ignores any signs of impending failure. What you will likely see is the pedal start to loosen and play develop at the interface. This assumes a good quality bolt was used. If the bolt is normal mild steel, there might be problems.

I say this because if the interface is tight, the bolt should be in pure tension with all bending loads taken up by the shoulder of the pedal axle and the formerly threaded part of the pedal axle itself taking up shear (as is the normal situation). If the interface loosens at all and play develops, then the bolt and washer starts taking up shear and bending loads, which is not good since the bolt is undersized and will fail fairly quickly under these conditions.