What is the current king of aluminum in 2017?

Discuss light weight issues concerning road bikes & parts.
Fiery
Posts: 420
Joined: Sat Mar 16, 2013 9:21 am

by Fiery

BMX market eclipses road and MTB combined? Care to share some numbers and/or sources?

Regarding seat post flexibility, smaller diameter can make up for thicker walls, the same way that oversize “beer can” tubesetes can be stiffer than those with thicker, narrower tubes. Think about it this way: a 4 mm steel rod has more material than a 10 mm steel tube with a 0.5 mm wall thickness, yet which one would you expect to be more flexible?

by Weenie


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prendrefeu
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by prendrefeu

My mistake, it does not eclipse the MTB market (which is still the most popular sales type)
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MikeD
Posts: 141
Joined: Thu Dec 11, 2014 9:55 pm

by MikeD

Whatever happened to scandium alloy aluminum frames? I thought that was good stuff.

morganb
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Joined: Wed Mar 15, 2017 5:30 pm

by morganb

MikeD wrote:
Thu Mar 01, 2018 4:21 pm
Whatever happened to scandium alloy aluminum frames? I thought that was good stuff.
They had poor fatigue resistance and were prone to cracking after a few years.

C36
Posts: 293
Joined: Fri Mar 03, 2017 3:24 am

by C36

morganb wrote:
MikeD wrote:
Thu Mar 01, 2018 4:21 pm
Whatever happened to scandium alloy aluminum frames? I thought that was good stuff.
They had poor fatigue resistance and were prone to cracking after a few years.
That was not related to the alloy. As an alloy the aluminiums with scandium had great mechanical properties. Making tubes too thin caused poor stiffness and high stress level that ultimately caused some frames not to last. Could add that not all the thermal treatment were always properly done.

Referring to one of my previous post, you can t compare from an engineering point, the coherence of a frame totally designed and welded internally versus a simple assembly of pre-existing tubes.



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stormur
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Location: FIN

by stormur

prendrefeu wrote:
Mon Feb 26, 2018 11:20 pm
Berk makes a 25.4 seatpost.
It's also a very, very common size for the BMX Market (which is far larger, and eclipses, the road & mountain markets combined). There are plenty of brand offerings for 25.4mm seatposts.
Name those plenty :) skip heavy steel posts for BMX ( useless info ) . How many is plenty ? ... let it be 7.

Point is, I had cannondale with 25.4 post . I rode it whole season . And I KNOW does it flex.. or not ( under my 85kg's butt ) It's not opinion nor estimation. Experience. Not so common here, isn't it ?
Go to Heaven for the climate, Hell for the company.
Mark Twain


I can be wrong, and have plenty of examples for that ;)

hambini
Posts: 297
Joined: Tue Nov 15, 2016 8:13 am

by hambini

freehub wrote:
Thu Feb 22, 2018 12:08 pm

In bold above. Just to be clear for anybody here that buys into Hambini videos who is standing on a nickel because he makes bottom brackets....his analysis is downright limited and misleading and Leuscher Teknik who is a bit more credible but the devil is mired more in the details which he doesn't go into with his 'light gloss' videos...any good engineer who has worked in this field...I have....understand's that Hambini...a great circus name btw....does a dis-service with his pseudo analysis. It is highly flawed. His measurement technique and analysis doesn't take into account the entire tolerance stackup of not only BB30 bearing misalignment, but their true position in respective bores but most notably lack of accomodating bearing tolerances which by design account for bore misalignment and also crankspindle relative to bearing bore I.D's. Evaluating or comparing BB30 bore misalignment in a vacuum as he does is basically irresponsible.

I know this is well beyond the scope of this forum but in summary, the engineers that design the top frames from the top bike companies understand this. Are all bikes shipped from the top factories perfect? No. Are almost all buildable and ride well with proper BB set up? Absolutely. If not they should be returned to the mfr for replacement frame just like for any mfg defect like poor paint quality.

As to the picture shown with ovalized BB. If this came from the factory like this, than of course it is a rejected frame that should be returned for a replacement frame. But pictures like this posted on the internet are abused frames with unknown background. Reality is...if a BB30 bike has a seized bearing due to neglect or abuse....unlubricated bearing subjected to a lot of poor weather riding....the bearing will seize and can ovalize the BB bore. An ovalized bore is many times accompanied by insufficient bearing preload....a condition lost on many that set up BB30. In particular this is a common issue with Shimano cranks that are among my favorite because of their mechanical preload. If preload is misadjusted...either too tight or too loose and non angular contact bearings are used, and the bearings aren't lubricated properly to repel contamination from the environment...and even add it a higher watt rider, you have a perfect storm...a high side of tolerance BB30's will aggrevate this as well. So few understand the true dynamic at play. They only know, they end up with an ovalized BB and don't know why. Virtually all if not most can be avoided with proper set up and good bearing selection and adequate maintenance. This can happen even in degree over time.

PF30 is even more sensitive to this with carbon bores. So is BB90 what Trek makes who uses a metal bearing on a carbon bore and unserviced bearings...or common lack of bearing pre-load causes bearing motion in the bore and elongation to the bores aggrevated by poor abrasion resistance of carbon. BB30 is not only better in abrasion resistance of bores compared to BB90 but have better bearing bore alignment with CNC bore machining.

For those interested, there is a great level of misunderstanding about press fit on the web. The vast majority don't really understand the design, how its manufactured, what the engineers responsible for it evaluate to ensure its performance etc. Yes, some press fit designs are better than others. Even PF30 can now be tamed by conversion sleeves from the aftermarket or now integrated bearings into cups. Early PF30 bikes had separate delrin cups and bearings and those that worked on them or owned such a bike know what an unmitigated disaster they were...and yes a sad commentary that companies from the aftermarket, saw the flawed designs being promugated and foisted upon the bike riding public from top bike brands and these aftermarket companies created a better mousetrap...in effect, a highly engineered kluge...to bail out these top brand bike makers to make their flagship bicycles more reliable. A sad commentary indeed. But among all of press fit in all its permutations out there, BB30 is among the most reliable if set up properly with Loctite. And for those who don't like to glue metal bearings to metal bores to ensure 0 creaking with proper crank preload often missed, then the aftermarket has come forward yes again...companies like Wheel Mfg and Praxis with their sleeves with integrated bearings which work nicely as well. Of course, all needless when a threaded 68mm shell with threaded outboard cups with integrated bearings aka Shimano, works pretty flawlessly. In summary, pick your frameset of choice carefully. Pinarello and Specialized moved away from their version of PF30....Pinarello in their wisdom, all the way back to 68mm BSA for their most expensive Dogma bikes which are excellent and won the TdF now 3 times.. for a reason after too long.
My points:

1. BB30 is poor because of rubbish execution and having the bearings close together. A wider stance (BB386/bb86) is more forgiving.
2. While you might criticise my measuring techniques (I use a CMM machine/ a laser or other means). You can't really argue with the multitude of reviews of people who use my bottom brackets and suddenly their creak has gone. It's not coincidental.
3. If you watch some of the other videos, you will know that I used to supply one of the manufacturers you have highlighted in your post with bottom brackets because they had lots of warranty claims for creaking (that's direct to the UK distributor, so they knew they had a problem). When they wanted to slacken their tolerances off and make my bottom brackets a factory fit, I refused because I did not want my engineering to be associated with poor quality and that is how I ended up on youtube and in the position I am in now.
4. I don't make my videos to sell bottom brackets, I could quite happily stop supplying bottom brackets - I have a comfortable day job. I enjoy imparting engineering info to the public. I much prefer the aerodynamics but I have become known for the bottom brackets.


And whilst you may disagree with the way anyone goes about doing things, referring to my name as a circus act is pretty low.

Thanks

Hambini

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