JimmyJ

I was just wondering if their are any problems which could arrise, and if so how likely, from helicoils.

i.e:
>will they fall out after a year?

>will they damage new pedals?

>can i then when need to replace chain set be able too take out the pedals and put into new chainset?

>will performance of bike be affected?

>or are they virtually like just riding normal bike?


The chainset (truvativ 2.2 gxp Elita) and bottom bracket are brand new and have had less than 50 miles covered on them. I cross-threaded my pedal into the crank arm. It has totally worn out the thread on crank arm (driveside).

I have taken bike to local bike shop and have asked for a helicoil put into crank arm and then new pedals put in. I have opted for the Shimano DX M647 dual platform and spd (Doublesided) pedal - best of both worlds. The local bike shop stated that it would not be as good as replacing the whole chainset and was wondering to what degree is it 'not as good'?

AlmostTrick

Will they fall out after a year?
No, if they are going to fall out it will happen long before then.

will they damage new pedals?
No, the pedals will thread into the new helicoil threads, which are the correct size and undamaged.

can i then when need to replace chain set be able too take out the pedals and put into new chainset?
Yes. Locktight the helicoil to the crank, and apply anti seize lube to the pedal threads.

will performance of bike be affected?
Only if the repair is not drilled "straight" or it works itself loose.

I've used helicoils on other things (mostly cars or machines at work) with good results, but never tried them on a bike crank. I'd like to hear from someone who has. I think as long as the repair is done properly, it will be fine.

Sawtooth

From my research, Helicoils are roughly equal to the original tapping. I think they want to sell a new drivetrain.

JimmyJ

On the topic of cross-threading is it down to the quallity of the components (crank arm thread and pedal thread) which causes the cross-threading or is it down to just purely inserting the pedal incorrectly? Or combination of two?

merlin55

Make sure they install a "non-locking" Helicoil. Locking Heicoils....and you may not be able to remove your pedal....ever

Booger1

It is stronger than the original thread.Won't fall out if put in correctly.Will ride like a circus bike if the coil is not put into the crank arm straight.

Nightshade

Why the whole set? Why not just the damaged arm?

In this application a Helicoil is NOT a good idea at all. Why you say? The load in the pedal is a "side
load twist" is why. Helicoils are great for straight pull or clamping applications but not side load.

Sorry to say this is a "replace what's broken" not a "repair what's broken" job.

AlmostTrick

This may be true, but I bet it would still hold on a pedal. Even if it didn't it wouldn't just "snap off" or anything catastrophic like that. Most likely it would just gradually work it's way loose and be detected long before it fell off. It would be worth a try in my book, but only if I was doing the repair myself. Paying a shop to repair it would probably cost almost as much as paying them to replace it.

unterhausen

helicoils are fine in this application. I think most bike shops actually have some kind of sleeve though. The only problem I see is that the pedal/crank interface is a known fatigue initiation point. You are weakening the crank, and the thread quality probably will not be as good.

Nightshade

Part of my point indeed. The other part is why be penney wise and pound foolish when you know
a new part is the best answer?

JimmyJ

I have enquired about just replacing the driveside crank arm but two problems:
1) item disconituned
2) it was only sold as complete unit (chainset, crank arm and bottom bracket).

because whole bike less than 6weeks old and had only about 70km clocked up I thought as a temporary measure just use the helicoil, for the next year or two. By that time the bottom bracket may need replacing, or just replace it anyway, along with the chainset and crank arms.

There is nothing worse than buying a new bike and then having to spend another small fortune on the chainset when it has not had a good innings. I take on baord the Taurus stance of 'it it aint broke dont fix it, and if its broke it might be better of that way anyway.'

I have taken my bike in for the helicoil repairs now so will see how well it goes.

ghettocruiser

Threaded inserts for the pedals are original equipment on some mountain bike cranksets.

I really like them, having wasted some threads in my day off-road.

unterhausen

I would probably get it done. I would also inspect frequently for cracks they don't grow that fast.

Nightshade

Part discontinued on a new bike?!? Major Bummer!

Looks like it's gonna have'ta get a helicoil patch job.

Grim

There is nothing wrong with helicoils and if done correctly it will be every bit as strong as new. There are many applications where NEW aluminum parts have Helicoils as design. Aluminum can be damaged easily when threaded. Helicoils are stainless steel. If it is an assembly that has to be taken apart regularly the stainless steel thread well be less likely to get damaged and since it is not being removed from the Aluminum it will protect the aluminum from damage.

I always Helicoil Exhaust bolt holes on Aluminum heads on car engines if I ever had to take them off for a repair. I was having far to many problems where once the exhaust was removed the threads were galled or pulling out form the heat cycling. NEVER had a problem with them after the helicoils were installed.

Bill Kapaun

Assume the Helicoil WILL damage your pedal when you remove it years down the road. (unlikely)
How much does a new set of pedals & a Helicoil repair cost vs a NEW crankset?

CommuterRun

I haven't used a Helicoil in this particular application, but I doubt, if properly installed, you would ever know it is there, for the life of the bike. If anything, a Helicoil will probably make pedal removal easier, while securely retaining the pedal while in use.

Nightshade

I guess the basic issue is "Do get it repaired right for long term use.....or.....do I go cheap now
as an excuse to buy a new bike while I risk injury on a patch job? "

The helicoil was invented to patch a hole not repair a hole. Nothing more or less.

Grim

Its a shame you were not around to tell Ferdinand he was an idiot and should not use them in those junk engines he was building.

https://books.google.com/books?id=el6...LbR6g#PPA22,M2