Dean Ti seatpost lightening hardware

[one-eyed_jim]

your prob right, but the Dean barrel is i think twice as big and more than twice as heavy as the set used in my Syncros post.

the barrel/bolt from the Dean seems to weigh as much as the two piece (aluminum?) clamps they are holding together.

also the barrel from my Syncros is yellow in colour, brass perhaps???

The classic Syncros posts used brass barrel nuts. The later ones moved to aluminium.

I think you're right that you should be able to use aluminium barrel nuts and Ti bolts here. The parts invoved seem a lot beefier than they need to be, judging by the parts that work in similar settings. If you can't find barrel nuts to suit, someone with the right equipment could make a pair very easily from 10mm rod. If you want to be fancy, you could Helicoil the threads...

 

[therapy]

RockiMtn, the clamping hardware is for 99% made by Tahoma. I've got a Bike-Tech Fat Tube seatpost which clamp looks exactly like yours - it's also Tahoma made.

The barrels are 10mm diameter, I've made mine from aluminium (6061) and it works very well - if you are not trying to overtighten the bolts . I've also change stock steel bolts (M6x30mm) for Ti and used a file to scrub the clamp a little here and there.

All these changes have following weight gain:

steel barrels -> alu barrels - 15,0g
stock steel bolts -> ti bolts - 8,4g
clamp scrubbing about 6g

So its about 30g lighter without sacrifying strength. I am about 210lbs rider and for me its safe enough. No problems at all.

you could Helicoil the threads...

Sorry mate, not in this place. Helicoil cannot be used in high stress areas.

 

[one-eyed_jim]

Sorry mate, not in this place. Helicoil cannot be used in high stress areas.

So what's that Helicoil doing in my single-bolt XTR M900 seatpost head?

:?

 

[Anthony]

Volume for volume (as opposed to weight for weight), steel is so much stronger than ti

you sure about that??? :?:

Yes, ti is far less dense than steel.

A ti tube that is just as strong as a steel tube will typically be fatter and much thicker gauge (and not even butted). My Columbus Cyber Kilauea has a 28.6 x 7-4-7 top tube, but you'll never find a ti bike with a top tube anything like as thin as 0.4mm.

 

[therapy]

So what's that Helicoil doing in my single-bolt XTR M900 seatpost head?

Maybe, I'm too careful, but in your seatpost the bolt is almost in line with force, the clamp takes more of the stress form saddle. In two bolt design like this, the bolt are stressed more, cause they keep the saddle straight.

I know that Helicoil cannot be used in high stress areas from a guy which sells them and I know that there are few places in a bike for which Helicoil wont work or will work very short.

Your works well, thats good, but hey, we have probabilty .

 

[Andy R]

Helicoil cannot be used in high stress areas.

I'm sorry, but this is just not correct - there are plenty of "high stress" applications where a helicoil repair is stronger than the original fixing.
For example - the repair of stripped cylinder head stud threads in an aluminium block or barrel.
The limitations to the use of "Helicoil" inserts relate to the integrity of the surrounding material , ie- if by tapping out to a larger size to take the insert you reduce the strength of the component unacceptably, then this is an application where helicoiling may not be used.

 

[therapy]

Andy R, not that you aren't right, but it depends. For example a helicoil repaired pedal thread in a crank worked well but for few rides. If the load is parallel to the direction of threading, than its mostly ok, but it often causes problems when its not. Every could have its opinion and experience, so also I appreciate yours .

 

[Andy R]

Here's what Machinery's Handbook has to say on the subject -

 

[RockiMtn]

wow, my thread got hijacked by helicoil! and i don't even really know what it is!

i might just give the Ti Thompson set a try. it's not a perfect fit but it might work. i got measurements of 9mm OD and 15.5mm L from TorontoCycles.

just seemed (top) heavy when i got it in the mail. and when i took it apart, the barrel/bolts seemed excessively heavy. plus the finish quality looked poor.

again, if anyone knows of where i can source proper sized replacement, that be appreciated!

 

[therapy]

Agree with that, but there nothing about the direction of the load on a thread . OK, lets end the OT. If we could met, sitting with a cold beer, we certainly could come to terms .

RockiMtn, read my first post.