A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Unicycling
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Titanium Hub?



 
 
Thread Tools Display Modes
  #11  
Old January 12th 09, 06:05 AM posted to rec.sport.unicycling
pedrotejada
external usenet poster
 
Posts: 445
Default Titanium Hub?


gerblefranklin;1169169 wrote:

pedrotejada,
Titanium is NOT rigid. It has a significantly lower modulous of
elasticity than steel




Sorry I read that around here! I must find the post, but If I'm not
right, someone posted that the titanium weld is also harder cause the
material is harder and if the weld is weak it will not absorve much
impact as aluminium does. I must find it...

Anyway both, Ti and stell are rigind materials aren't?

About ti welding theres a site that teach many ways to make Ti bike
frames. I think I have it bookmarked and can try to find. The proposed
some realy interesting welds for low surface situations that I tought
maybe would fit a flat frame. Until now I'm only designing the seatpost
... Soon I will have my prototype and also an American Rider will test
it

Sorry about my error! that makes things clear!


--
pedrotejada

'*Kris Holm Unicycles*' (http://www.krisholm.com)

'*Unicycle.com.br*' (http://www.unicycle.com.br/)

*Brazilian Unicycling Team*
------------------------------------------------------------------------
pedrotejada's Profile: http://www.unicyclist.com/profile/14471
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
Ads
  #12  
Old January 12th 09, 10:57 AM posted to rec.sport.unicycling
jogi
external usenet poster
 
Posts: 24
Default Titanium Hub?


you´re talking a lot about titan - in deed what´s with the
steal
in my oppinion the steal of the hub (not the axle!) is not very high
quality.
therefor its not so difficult to build a titan hub in higher strength /
lower weight.

jogi

PS: my TI KH - hub is about 210 gr les than my old KH Hub


--
jogi

municycling anarchist
26" K1 Track Monster
Surly Conandrum
KH36 Nightrider
24 K1 street

zitat smilymarco:
Es ist Knut, der kann das. Knut ist ein Tier!
------------------------------------------------------------------------
jogi's Profile: http://www.unicyclist.com/profile/14910
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #13  
Old January 12th 09, 03:34 PM posted to rec.sport.unicycling
danger_uni
external usenet poster
 
Posts: 343
Default Titanium Hub?


It's a common misconception that Titanium is "stronger" than steel, but
as mentioned above it depends on how it is measured.

Ti has a stronger strength to weight ratio than steel but a lower
strength to volume ratio.

It is also 60% heavier (by volume) than aluminum and has elastic
properties that work well in bike frames but are not advantageous for a
uni frame.

It's also a lot more expensive, obviously.

The lesson is that no material is perfect but some are better than
others for certain applications, and the challenge is to use the best
material for the right location.

On a uni, my opinion is that Ti offers only marginal advantage for a
frame because the flex issue requires Ti tubing with sufficient rigidity
that it is only marginally lighter at huge expense.

In the case of the hub, we are of course replacing CrMo so there is
significant weight savings. Since the volume of an ISIS axle is
constrained by geometry, a Ti axle is slightly weaker than a CrMo axle.
But while flange strength has been an issue, broken ISIS axles on a uni
hub are incredibly rare so functionally they can be considered similar.
Consequently the weight savings makes Ti, in my opinion, a very good
material for the hub.

The elastic properties of Ti make it good for the flanges and the Ti
flanges are also thicker than the CrMo flanges. So far there has been
only one broken Ti flange that I know of, and it appears to have been
faulty welding subject to warranty.

So in summary the Ti Moment hub is functionally similar in strength to
the CrMo hub but significantly lighter.

Kris


--
danger_uni
------------------------------------------------------------------------
danger_uni's Profile: http://www.unicyclist.com/profile/21
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #14  
Old January 12th 09, 03:41 PM posted to rec.sport.unicycling
GizmoDuck
external usenet poster
 
Posts: 811
Default Titanium Hub?


danger_uni;1169299 wrote:
It's a common misconception that Titanium is "stronger" than steel, but
as mentioned above it depends on how it is measured.

Ti has a stronger strength to weight ratio than steel but a lower
strength to volume ratio.

It is also 60% heavier (by volume) than aluminum and has elastic
properties that work well in bike frames but are not advantageous for a
uni frame.

It's also a lot more expensive, obviously.

The lesson is that no material is perfect but some are better than
others for certain applications, and the challenge is to use the best
material for the right location.

On a uni, my opinion is that Ti offers only marginal advantage for a
frame because the flex issue requires Ti tubing with sufficient rigidity
that it is only marginally lighter at huge expense.

In the case of the hub, we are of course replacing CrMo so there is
significant weight savings. Since the volume of an ISIS axle is
constrained by geometry, a Ti axle is slightly weaker than a CrMo axle.
But while flange strength has been an issue, broken ISIS axles on a uni
hub are incredibly rare so functionally they can be considered similar.
Consequently the weight savings makes Ti, in my opinion, a very good
material for the hub.

The elastic properties of Ti make it good for the flanges and the Ti
flanges are also thicker than the CrMo flanges. So far there has been
only one broken Ti flange that I know of, and it appears to have been
faulty welding subject to warranty.

So in summary the Ti Moment hub is functionally similar in strength to
the CrMo hub but significantly lighter.

Kris




There are a couple of other advantages you of Ti you haven't pointed
out:
-It's expensive You don't buy an expensive sportscar because it is
slightly better at getting you from A to B. You buy it because not
every Tom, Joe and Mary has one.
-It looks cool
-No need to paint it (saves more weight and scratches)

As for the hub, why aren't there any aluminium hubs? Most good bike
hubs I know are aluminium, and they're pretty strong and light.


--
GizmoDuck

The Induni Unicycle Tour 2009. Unicycle Tour of India. Email me for
details. www.induni.adventureunicyclist.com
The Uninam Tour 2008.....Hanoi to Saigon!!! www.uninam.net
The SINZ Unicycle Tour 2007....South Island, New Zealand
www.sinzuni.org
------------------------------------------------------------------------
GizmoDuck's Profile: http://www.unicyclist.com/profile/794
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #15  
Old January 12th 09, 04:04 PM posted to rec.sport.unicycling
agentQ
external usenet poster
 
Posts: 931
Default Titanium Hub?


GizmoDuck;1169301 wrote:


As for the hub, why aren't there any aluminium hubs? Most good bike
hubs I know are aluminium, and they're pretty strong and light.




You cant compare bike to unis here. Bikes do not come close to the
amount of torque and stress which is required from a unicycle hub.


--
agentQ

---
'Uneed Films' (http://www.uneedfilms.com)
------------------------------------------------------------------------
agentQ's Profile: http://www.unicyclist.com/profile/13021
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #16  
Old January 12th 09, 04:08 PM posted to rec.sport.unicycling
GizmoDuck
external usenet poster
 
Posts: 811
Default Titanium Hub?


agentQ;1169310 wrote:
You cant compare bike to unis here. Bikes do not come close to the
amount of torque and stress which is required from a unicycle hub.




Maybe, but I ride road and XC, not trials

Every single ISIS hub available to me right now except for the KH Ti is
too heavy and too strong for what I use it for.


--
GizmoDuck

The Induni Unicycle Tour 2009. Unicycle Tour of India. Email me for
details. www.induni.adventureunicyclist.com
The Uninam Tour 2008.....Hanoi to Saigon!!! www.uninam.net
The SINZ Unicycle Tour 2007....South Island, New Zealand
www.sinzuni.org
------------------------------------------------------------------------
GizmoDuck's Profile: http://www.unicyclist.com/profile/794
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #17  
Old January 12th 09, 07:49 PM posted to rec.sport.unicycling
olarf
external usenet poster
 
Posts: 177
Default Titanium Hub?


If you did the Hub from Aluminium, from what material you plan to do the
Cranks then ? Aluminium Cranks mounted on an Aluminium ISIS Hub could
result in some trouble I think.
Did you think you will feel the difference from 100 gramm maybe on a
36" or 29" while riding ? Didn't the tire itself influence it much more
?

I also see to many Bike parts (which are very light mostly) brake week
by week in the Hall where we do training. I love to have a trusted
feeling in my hub and parts while riding a vehicle (mono, bike, moto...)


--
olarf

'unicycle.tv' (http://www.unicycle.tv)
'gunf.org' (http://www.gunf.org)
'e-u-c.info' (http://www.e-u-c.info)
'IUF' (http://unicycling.org/iuf/)
------------------------------------------------------------------------
olarf's Profile: http://www.unicyclist.com/profile/10588
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #18  
Old January 12th 09, 08:04 PM posted to rec.sport.unicycling
danger_uni
external usenet poster
 
Posts: 343
Default Titanium Hub?


Good point. ISIS was never intended for an aluminum axle.

Weight savings can come from using a bigger hole through the axle (M15
axle bolt instead of an M12 bolt), but I've never offered an M15 option
because the market is very small, weight savings are not that noticeable
in the overall scheme of things, and it is really hard to predict what
people will do with a product once it's sold. I'd rather have
something a few grams heavier that is versatile for everything.

Making flanges and hub body from aluminum instead of CrMo doesn't save
much if any weight because the flanges and hub body use thicker
material; however it could provide a better flange surface and angle for
the spokes. I'm working on something in that regard but won't have
anything to release just yet.

Kris


--
danger_uni
------------------------------------------------------------------------
danger_uni's Profile: http://www.unicyclist.com/profile/21
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #19  
Old January 12th 09, 08:09 PM posted to rec.sport.unicycling
Rowan
external usenet poster
 
Posts: 154
Default Titanium Hub?


GizmoDuck;1169301 wrote:
There are a couple of other advantages of Ti you haven't pointed out:
-It's expensive You don't buy an expensive sportscar because it is
slightly better at getting you from A to B. You buy it because not
every Tom, Joe and Mary has one.


Lol, unicycle elitism. You buy it because there are not enough Titanium
hubs for everyone and you are one of the few with enough money. Very
typical Ken!


--
Rowan
------------------------------------------------------------------------
Rowan's Profile: http://www.unicyclist.com/profile/3772
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
  #20  
Old January 12th 09, 08:20 PM posted to rec.sport.unicycling
skrobo
external usenet poster
 
Posts: 2,129
Default Titanium Hub?


gerblefranklin;1169169 wrote:
The amount of misinformation in the cycling/RC anything/Motosports
communities is ridiculous. Any thread like this is a fine example.

pedrotejada,
Titanium is NOT rigid. It has a significantly lower modulous of
elasticity than steel ( http://tinyurl.com/8z68xw ), making it far
flexier. I seem to remember talking to Kris about this issue when
discussing whether titanium muni frames are worth the trouble. Also,
since the design of the steel and titanium hubs is essentially
identical, we can compare strength and make reasonable predictions. But
you are right to say good design work should account for material choice
therein.

Skorbro, your post makes it sound like you've never picked up a big
chunk of titanium while expecting it to be steel. It is a dramatic
experience to notice how light it is. And my source for the density and
strengths of materials is _Machinery's_Handbook,_27th_Edition_. Go buy
yourself a copy if you don't believe me.

The density of titanium is, according to my copy of
_Machinery's_Handbook,_27th_Edition_, 0.163 lb/in^3, while steel is 0.25
lb/in^3. So titanium is about 35% less dense.

In a situation where strength is the ultimate issue, and the dimensions
of the part are fixed (we can't make bigger ISIS splines), what matters
are the strength to volume ratios. 6Al-4V titanium, the alloy which I
believe Kris uses in the hubs, has a (0.5% ?) yield strength ranging
from 120-160 ksi, depending on heat treatment. While 4130/4140 steel,
depending on heat treat, has a 0.2% yield strength of 100-155 ksi. 4130
steel can be made much harder than 6Al-4V titanium. So if the titanium
hub is fabricated perfectly, it can be of comparable strength to the
steel hub, but it is unlikely to ever exceed the steel hub's strength. I
am ignoring spline hardness, by the way, since I assume no rider is
regularly changing cranks.

Now, factor in the issues with the difficulty of welding titanium, and
quality control thereof, and the titanium hub's strength is an issue.
Hence the fact that a much smaller sample of riders has already broken a
titanium hub, while I, at least, have never seen a broken steel hub. If
the titanium hub were machined from solid (prohibitively expensive), I
would have more faith in its durability.

You would not be wrong to argue that the softer titanium hub builds a
stronger wheel by conforming to the spokes better, but I don't think
that's where a hub will be failing.

I hope this clears things up. And the answer to the original question
is, the titanium hub is ONLY worth getting if you aren't breaking the
steel hub. If you are, you should either switch to profile, or get a
custom built hub/crankset with a larger splined interface.

P.S. Rowan, you are right. I did mean Joe Dyson.




i have not dealt much at all with titanium, but i knew there was
misinformation in the posts, so i was hoping that i would draw out a
post like yours faster, and alert everyone to the misinformation.

its all good now.

interesting stuff...


--
skrobo

Unicycle For Christ

'MY VIDEOS' (http://www.youtube.com/profile?user=skroboskim)
'World Record' (http://www.youtube.com/watch?v=oig5IEq-v4Y)
94cm Highest Hop (rolling)
308cm Longest Hop (10 feet)
210cm Static Flat Gap
------------------------------------------------------------------------
skrobo's Profile: http://www.unicyclist.com/profile/12272
View this thread: http://www.unicyclist.com/thread/75414


Posted Via Usenet.com Premium Usenet Newsgroup Services
----------------------------------------------------------
http://www.usenet.com
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Titanium Hub? IsaacSteiner Unicycling 0 January 11th 09 12:58 AM
...but titanium is Andre Jute[_2_] Techniques 29 June 2nd 08 04:06 PM
Titanium what ever Techniques 1 November 10th 04 05:59 PM
Titanium what ever Techniques 0 November 10th 04 02:10 AM
Titanium flyingdutch Australia 33 April 3rd 04 10:54 AM


All times are GMT +1. The time now is 12:34 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.