Mountain Bike Reviews Forum banner

1 - 20 of 104 Posts

·
Registered
Joined
·
46 Posts
Discussion Starter · #1 ·
I am not a math wiz, but after seeing an add (last pic below) by Giant in Sept issue of MBA on the benefits of the 27.5" wheel vs a 26er and 29er and then reading an article from Keith Scott engineer at Banshee bikes (Educating the Debate 1,2,3, links are below), it appears to me that Giant is lying to us about 27.5".

First off, they no longer say 650b, they say 27.5" which implies the wheel is 1.5" larger than a 26". However, a 27.5" wheel is actually only 1" larger than a 26". I realize the terms to describe the wheels are not actually the diameter of the wheel, but this is very deceiving. Second, the pictures in the add make the 27.5" wheel look about the same size as the 29er, when a 27.5" wheel is much closer to a 26er. Again, deceiving.

Now for the more technical stuff that I don't have the math skills for so, please, anyone who understands this kind of math, help me with which is true.

In the add and on Giant's web site (link below if you can't read the add) Giant says that a 27.5" rolls over a 6cm object 9.8% more efficiently than a 26er and that a 29er rolls over a 6cm object 14% more efficiently. However, fig 4 (angle of attack vs height if obstacle, first pic below) in part 2 of the article by Keith appears to show that a 650b rolls over a 60mm object about 2.5% more efficiently than a 26er and a 29er rolls over a 60mm object about 6% more efficiently than a 26er.

Which is true?

Giant also says that a 27.5" wheel will have a 4 degree shallower angle when rolling over a 6cm object and a 29er will have a 6 degree shallower angle when rolling over a 6cm object (pic 2 below). However, fig 2 (Tan relative to 650b % vs height of obstacle, pic 3 below) appears to show the ratio to be the opposite, where if 650b has a 2 degree shallower angle, a 29er would have a 6 degree shallower angle.

Which is true?

Finally, giant says that a 26er has about 6cm length of contact patch, a 27.5" has a 8cm length contact patch and a 29er has a 9cm length contact patch (pic 4 below). However, in part 3 of the article by Keith, fig 4 (pic 5 below) appears to show the opposite ratio that giant states, where the contact patch for a 2.3" wide 650b tire is 1.81mm longer than a 26er with a 2.3" wide tire and the contact patch for a 29er with a 2.3" wide tire is 2.7mm longer than a 650b making the 650b contact patch closer to a 26er than a 29er.

Which is true?

27.5 Technology | Technology - Giant Bicycles | United States

Educating the Debate pt 1

Educating the Debate pt 2
Educating the Debate pt 3
 

Attachments

·
Trail Ninja
Joined
·
6,168 Posts
Welcome to mtn bike marketing. Note that 26" wheels are closer to 27" than they are to 26" with average sized mtb tires these days.
 

·
Registered
Joined
·
542 Posts
But what possible motivation could a massive and potentially monopolistic corporation like Giant have to lie?

Would lying enable Giant to reap massive financial rewards, if only Giant manages to convince everyone that 650b is actually 27.5? And that 650b has all the brnifits and none of the compromises or losses? Especially if they use exaggerated and questionable numbers to suggest these improvements?

Especially considering that Giant has gone "all in" betting on 650b?

Would it be financial ruin for Giant if the market decides that 26" and 29" are a better? At this point, it would be a huge climb down for Giant to promote anything besides 650b. Which could be detrimental to their financial out look, not to mention the trust lost between producer and client. So does it make sense for Giant to double down and lie about immutable physics to protect profits?

Additionally, in this case, if the "world" buys into Giant's plans, then does Giant benifit by producing a single rim and tire size, reaping rewards of scale, while offering the consumer less choice, not more choice? Is less choice the road to innovation?

I know what I would answer to each of these questions.

And I know which brand(s) and sub- brands that I will never buy a cycling product from ever again.

What about you?

For free markets to work capitalism requires a well informed consumer. This honest, transparent, and clear communication and information can then be used by the consumer to vote with their dollars.

Truthful and clear companies that provide options for the consumer will succeed.

Companies that lie, confuse, and obscure information to limit choice and boost their own profits will fail.

I know which of these categories I think Giant falls onto.

And conversely, I also know which of these categories I think Banshee falls into.
 

·
Registered
Joined
·
107 Posts
I love the way they casually jump back and forth between comparing the "27.5" to either the 26 or 29 depending on which suits their propaganda, makes the "27.5" look like the obvious choice in all situations...But to be honest I think anyone who rely's solely on a manufactures marketing info to make a decision on the best bike for their needs pretty much deserves to be parted from his cash.
 

·
The joy of ski is Yours
Joined
·
1,367 Posts
Christ on a Bike...

Do consider nearly all marketing is created to include those who are new, uninitiated riders. 29'r kind of planked it's way into the sport as the pedal-ie alternative to the standard bike setup - and not without it's shortcomings.

That aside, the biggest 2.5" tire to a 26 inch rim will have the effective diameter of a 27.5" w/ a XC-type tire.
The ad seems to use applied math with the understanding that user choice of tire will effect total finish.
 

·
DeForest Stump
Joined
·
972 Posts
What about the coefficient of friction vs. the initial damped mass vs. the rotational fluxations of the 26-27.5-29 inch wheel sizes? More studies are needed in these areas before a final verdict can be reached.
 

·
Registered
Joined
·
542 Posts
Math can be deceiving. Consider that an average person would have one testicle and one overy.

Ride and see what works for you and the riding you do.m
This stuff is mostly physics, not math. And averages fall under statistics, not math. And the proper use/rules of stastics precludes the type of averaging you've used in your example.
 

·
Never Forget 9-11
Joined
·
434 Posts
All bikes are great. Go for a test ride. If you like it, buy it. If you don't like it. don't buy it. Less reading more riding.
 

·
Registered
Joined
·
2,701 Posts
I like riding my bikes.

The rest of this is just so much drivel and not worth the effort.
All bikes are great. Go for a test ride. If you like it, buy it. If you don't like it. don't buy it. Less reading more riding.
In all fairness, aren't threads like this one of the main reason for having Internet forums? Clearly we're all here because we enjoy riding in one capacity or another, but we're also here because we enjoy discussing "hot button" issues in the biking community/industry. Saying "don't concern yourself with it and just go out and ride" short of frustrates the purpose of being on a forum, no?

Posted via mobile
 

·
Registered
Joined
·
5,764 Posts
You are being confused by a bunch of marketeers at an advertising firm, whom themselves don't actually know what they are talking about. Giant fed them a bunch of numbers, but because they don't know what they are talking about, they can't properly fact check anything.
I automatically assume any claim made in marketing propaganda is false or twisted in a way to make the companies product look good. A healthy dose of cynicism keeps you from being fooled by the marketeers.
 

·
Rabid Lana Fan
Joined
·
9,304 Posts
In all fairness, aren't threads like this one of the main reason for having Internet forums? Clearly we're all here because we enjoy riding in one capacity or another, but we're also here because we enjoy discussing "hot button" issues in the biking community/industry. Saying "don't concern yourself with it and just go out and ride" short of frustrates the purpose of being on a forum, no?

Posted via mobile
This is all true.

But why are people so surprised/pissed/shocked that marketing tries to get consumers on board with thier product. That is, after all, what marketing firms are paid to do.
 

·
Registered
Joined
·
2,701 Posts
I think it's that there are two ways to go about it. The claims of the OP are that they are flat out lying which, in my opinion, is discussion worthy. It's the responsibility of a large corporation engaged in even the most tactful marketing to su last be truthful

Posted via mobile
 

·
The Original Suspect
Joined
·
2,383 Posts
Nobody is going to advertise a product and say it sucks. Being that Giant dropped their 26 line, they of course need to prove by any means that their current offerings are superior to the line they no longer carry.
 
1 - 20 of 104 Posts
Top