Rounded bolt - TCR

GSSK

The fizik saddle kept slipping and while trying to tighten down the bolt again it appears I've rounded the 5mm hex bolt clamping the saddle down in the seat post. Bike's a TCR Advanced 2 2016.
Is it best to have the bolt drilled out and a new one in or to buy a new seat post? I imagine if it's the former the LBS would be a good place to do this?

Thanks for any help

Matthewfalle

Can't picture it mentally - can you post a piccie?

If it needs drilling out then it's not a big job - you, a normal drill, a couple of drill bits and some care and attention will do it fine.

If you're going to lob the seat post can I baggsie it please?

GSSK

Matthewfalle wrote:

Can't picture it mentally - can you post a piccie?

If it needs drilling out then it's not a big job - you, a normal drill, a couple of drill bits and some care and attention will do it fine.

If you're going to lob the seat post can I baggsie it please?

Haha, unless it's not possible I'd rather keep the seat post.

bbrap

Seeing that it is a female hex cap head bolt you may not have to drill it. Try an "easyout", a left hand thread thing which will screw into (anticlockwise) the hex hole and free the bolt. Most garages (mechanics) have them and once removed you will just need a couple of new bolts.

Matthewfalle

I was just going to type that

Buy Eazy Out and corresponding drill bit: drill hole through centre of bolt then screw in Eazy Out - it should unscrew the bolt.

Otherwise it's not a biggy, just fiddly one to drill out. Remember that you don't need to drill it so it's completely gone, just so that it collapses in on itself. Drill the majority of it out, ram a screwdriver in and unscrew.

If it's a cheap saddle that you don't mind losing, you can also cut the rails off then unscrew the bolt that the now duffed bolt goes into.

I'd also try smacking in an Allen key 1/2 mm bigger than what you are using and see if that purchases in enough to undo it: decent tool factor will be able to sell these to you on andividual size basis.

HTH.

GSSK

I see they need a drill, I don't have one where I am currently. I might just get the LBS to sort it out when the service is due in a week and a half.

I've tried a 5.5mm allen key but it's too big still.

bbrap

If you get the right size easyout it will wedge in the existing hex hole without drilling.

GSSK

bbrap wrote:

If you get the right size easyout it will wedge in the existing hex hole without drilling.

Hmmm are you able to point me in the direction of a size? Same size or bigger? A link to some would be good, had a quick peruse on Amazon and seemed to have mixed reviews about being cheese.

mamba80

GSSK wrote:

bbrap wrote:

If you get the right size easyout it will wedge in the existing hex hole without drilling.

Hmmm are you able to point me in the direction of a size? Same size or bigger? A link to some would be good, had a quick peruse on Amazon and seemed to have mixed reviews about being cheese.

i have used a socket torx bit taped into the hex, with success - just buy a cheap set and use the largest that will tap in.

bbrap

GSSK wrote:

bbrap wrote:

If you get the right size easyout it will wedge in the existing hex hole without drilling.

Hmmm are you able to point me in the direction of a size? Same size or bigger? A link to some would be good, had a quick peruse on Amazon and seemed to have mixed reviews about being cheese.

If you buy one of the cheap sets available on eBay for two or three pounds they usually are sets of 5. Looking at your bolt either the 2nd or 3rd in the set should do it. Treat the tool as a disposable item, if it breaks you have only lost a couple of quid and still have the option of getting someone to drill it out. Looking at the seatpost once the tension is off one of the bolts the other one will become loose. So in effect you have two bolts with which to try an extraction.

Ignore that last remark, I thought there was another bolt the other side of the post, but there is only one.

GSSK

bbrap wrote:

GSSK wrote:

bbrap wrote:

If you get the right size easyout it will wedge in the existing hex hole without drilling.

Hmmm are you able to point me in the direction of a size? Same size or bigger? A link to some would be good, had a quick peruse on Amazon and seemed to have mixed reviews about being cheese.

If you buy one of the cheap sets available on eBay for two or three pounds they usually are sets of 5. Looking at your bolt either the 2nd or 3rd in the set should do it. Treat the tool as a disposable item, if it breaks you have only lost a couple of quid and still have the option of getting someone to drill it out. Looking at the seatpost once the tension is off one of the bolts the other one will become loose. So in effect you have two bolts with which to try an extraction.

Ignore that last remark, I thought there was another bolt the other side of the post, but there is only one.

I'll give that a go. There is another bolt but it doesn't use any wrenches, not sure of its actual name but it's like a thumb bolt almost at the front that is used to adjust the angle.

Matthewfalle

Piccie?

jermas

If you can undo the "thumb bolt" (angle adjuster) with pliers or mole-grips that'll release the tension in the rounded bolt. It should come out easily then.

GSSK

jermas wrote:

If you can undo the "thumb bolt" (angle adjuster) with pliers or mole-grips that'll release the tension in the rounded bolt. It should come out easily then.

Woefully under equipped while I'm at uni, no pliers around.

ElectronShepherd

Take it to the Mechanical Engineering dept, and say it's a project for them!

GSSK

ElectronShepherd wrote:

Take it to the Mechanical Engineering dept, and say it's a project for them!

That'd probably save a few pennies

frisbee

Easy outs are a great way of going from soft, easily drilled material to hardened, impossible to drill material.

They have a horrible tendency to snap.

Just hammer a torx bit into it.

GSSK

So I've managed to remove the thumb screw using a pair of pliers as suggested, meant I've not got the saddle off. But I can't get the hex bolt out still, though I could perhaps spin it free but this just seems to achieve nothing.

jermas

The round piece (nut) that the bolt's threaded into will need to be held tight whist unscrewing the bolt. 2 pairs of piers might be handy.

bbrap

jermas wrote:

The round piece (nut) that the bolt's threaded into will need to be held tight whist unscrewing the bolt. 2 pairs of piers might be handy.

As above, except take the seatpost off the bike, clamp the bolt head in a vice, then use pliers on the round bit (waterpump pliers grip pretty well). There must be somewhere at your uni with a vice (ask the vice chancellor :P ).

GSSK

bbrap wrote:

jermas wrote:

The round piece (nut) that the bolt's threaded into will need to be held tight whist unscrewing the bolt. 2 pairs of piers might be handy.

As above, except take the seatpost off the bike, clamp the bolt head in a vice, then use pliers on the round bit (waterpump pliers grip pretty well). There must be somewhere at your uni with a vice (ask the vice chancellor :P ).

Joke was terrible but it's got a 6 week service next week so worse comes to worse I'll get them to sort it out then, although I doubt rounded bolts is included.

Although I don't want to have to spend a week riding only indoors, am I doing something wrong with two pliers - I had one on the lock ring and one one on the thread (can't get a grip on the head and on the lock ring)? Doesn't seem to be achieving anything but ruining the thread.

Jonesinamilion

Never tried on a hex, but on a standard bolt you can cut a slot in using a Dremel with cutting disk then use a flat head driver.

sandyballs

From the way this is dragging on I would suggest your not your the most mechanical minded and would recommend you get that to a shop soonest and a proper one at that. A new seat post is £100 if you can find stock and the hardware alone if you knack that up is £35 again if you can find stock.

http://www.pedalon.co.uk/acatalog/Giant-Vector-Carbon-Seatpost.html

I bought a second hand TCR Adv frame set and managed to find a seat post after the previous owner mullerred it but it took a while.

GSSK

Sandyballs wrote:

From the way this is dragging on I would suggest your not your the most mechanical minded and would recommend you get that to a shop soonest and a proper one at that. A new seat post is £100 if you can find stock and the hardware alone if you knack that up is £35 again if you can find stock.

http://www.pedalon.co.uk/acatalog/Giant-Vector-Carbon-Seatpost.html

I bought a second hand TCR Adv frame set and managed to find a seat post after the previous owner mullerred it but it took a while.

Well a new seat post isn't actually needed as it's only one bolt in the clamp that needs replacing and you can get saddle rail replacement parts from Giant.

I'm no mechanic, but I also have very few tools with me so it's not possible to do most of the things suggested.

sandyballs

When you removed the pressure by undoing the knurled adjuster and seat you should be able to unscrew the stubborn bolt with your fingers. You should be able to see that the silver nut has straight sides that prevent it from spinning in the top plate. If you have damaged the thread above that nut it would be best to hacksaw it off since you don't want to drag that damaged thread all the way through the silver nut. My guess is there is either corrosion or damaged thread within the bolt or nut if it will not come apart once the pressure has been removed. The bolt is pennies the silver nut is unique to Giant.

Not having a dig but don't want costs to escalate due to lack of tools.

gaffer_slow

another option is to epoxy a nut onto the stripped head, and then use the nut to remove.

GSSK

Sandyballs wrote:

When you removed the pressure by undoing the knurled adjuster and seat you should be able to unscrew the stubborn bolt with your fingers. You should be able to see that the silver nut has straight sides that prevent it from spinning in the top plate. If you have damaged the thread above that nut it would be best to hacksaw it off since you don't want to drag that damaged thread all the way through the silver nut. My guess is there is either corrosion or damaged thread within the bolt or nut if it will not come apart once the pressure has been removed. The bolt is pennies the silver nut is unique to Giant.

Not having a dig but don't want costs to escalate due to lack of tools.

I appreciate that. I think it's time to admit it's beyond me and seek able help.

thistle_

ElectronShepherd wrote:

Take it to the Mechanical Engineering dept, and say it's a project for them!

+1

Ask around, find a lecturer/lab technician who rides. They'll have all kinds of tools, random experience and know others who can help.

The guys I knew with workshops were in the chemical engineering department and the psychology department (!)

mrb0139

I had the same problem, I had tried to cut the head and use a screw driver but no luck in the end I got my bro in law to sort he's a motorbike mechanic, he just said

"I used a battery impact gun in the slot you cut in the bolt. If you hadn't cut the bolt I would have tried an extractor first. Easy with the right tools but most people won't be able to do it at home I doubt, Make sure he has the inner bolt undone as well as that help take pressure off it"

So I had the seat post and saddle undamaged, only needed a new bolt. Hope this helps