26 vs 29....

[N0bodyOfTheGoat]

I can report to the forum that a 26x4" Jumbo Jim inflated to ~20PSI gives a fractionally larger circumference than a 29x2.35" G One Speed inflated to ~35PSI on my Voodoo Wazoo fatbike commuter.

Almost five years have gone by since the drive side crank sheared through pedal thread on my way to work, pedalling home uphill was fun!

I really must get around to trying to source a replacement crank, it was such a fun bike, despite used almost entirely on tarmac since being bought in early '16.

 

[Dogtrousers]

One thing that bugs me is why wheels aren't referred to by their actual size - the bead seat diameter (plus optionally rim width).

As far as I know "29 inch" wheels are actually 622mm, as are "700C". So two groups of cyclists have independently invented different stupid confusing names for the same thing.

I wouldn't mind if the confusing names were just names, like "Henry" or "Winkler". But they actually have a number in there that doesn't represent anything at all. Are 29" wheels actually 29"? Are 700C wheels 700mm? Ha! It depends what size tyres you fit, but the answer's almost certainly going to be "no, of course not". That's what makes them stupid as well as confusing.

Why?

 

[DCLane]

@Dogtrousers - agreed. My Merida Cyclo-Cross has 29" wheels and I'm using 700c tyres on it. It's because the 29" came out of MTB's not road bikes.

 

[Profpointy]

One thing that bugs me is why wheels aren't referred to by their actual size - the bead seat diameter (plus optionally rim width).

As far as I know "29 inch" wheels are actually 622mm, as are "700C". So two groups of cyclists have independently invented different stupid confusing names for the same thing.

I wouldn't mind if the confusing names were just names, like "Henry" or "Winkler". But they actually have a number in there that doesn't represent anything at all. Are 29" wheels actually 29"? Are 700C wheels 700mm? Ha! It depends what size tyres you fit, but the answer's almost certainly going to be "no, of course not". That's what makes them stupid as well as confusing.

Why?

I understand there's a proper standardised way of specifying rims, and even 700c isn't really a pukka naming convention.

Naturally we are going to have Yank numbering in inches vs rest-of-the world with a metric system, now we (in the UK) have abandoned 27" wheels on our "racers"

 

[Dogtrousers]

And it gets even worse. I think you could refer to 29er/700c as 688b with no loss of accuracy. You might think this is a stupid thing to do, but stupid things seem to be the standard.

But what I find super puzzling is the use of "C" for tyres and innertubes. So (e.g.) 28mm tyres(or tubes) are referred to as 28 C. That really makes no sense whatsoever. This is official too, you see it on packaging. And it's very stupid.

 

[si_c]

There are a number of advantages to both 26" and 29" wheel formats. For me I will opt for 29" wheels over 26" when I get a new MTB as the larger wheel size means the bikes are proportioned better for me. 26" wheels are stronger than 29ers though due to the better spoke bracing angles so for a reliable wheel I'd opt for a high spoke count 26" over most alternatives.

 

[Chris S]

One thing that bugs me is why wheels aren't referred to by their actual size - the bead seat diameter (plus optionally rim width).

As far as I know "29 inch" wheels are actually 622mm, as are "700C". So two groups of cyclists have independently invented different stupid confusing names for the same thing.

I wouldn't mind if the confusing names were just names, like "Henry" or "Winkler". But they actually have a number in there that doesn't represent anything at all. Are 29" wheels actually 29"? Are 700C wheels 700mm? Ha! It depends what size tyres you fit, but the answer's almost certainly going to be "no, of course not". That's what makes them stupid as well as confusing.

Why?

It's more esoteric. IYKYK.

 

[Drago]

29ers, love them, hate them, or be indifferent, aren't optimum for claggy British conditions.

When riding in the mud the extra circumference is just an opportunity to carry more mud, more weight, and be a general PITA.

Obviously not an issue in drier conditions.

So they're a lot worse in the mud than 26, but only a little better in the dry.
I know which I prefer, but the industry crested a trend and rode the wave. Giant, who were a bit later the the party were a bit miffed and used their might to start a trend of their own and pushed a revived 27.5 as the supposedly sensible middle ground and the buying public lapped it up.

Personally I find 26 and 27.5 so close that tyres are the determining factor rather than any notional difference in diameter, but it must be remembered that I have the sensitivity and fine motor skills of Abu Hamza.

Just ride what you like.

 

[Chris S]

As for "a longer chain makes a major loss of energy!"

That's your claim, therefore I'd like you to come up with the said formula to prove that. Keep in mind that the chain (roller chain) is a field of study in mechanical engineering that's well understood and described in text books and online academic journals. Roller chain energy losses can be calculated and even measured. It should therefore be very easy for you to substantiate your claim if there is evidence that it is true. Try ChatGPT if you like - no need even for exclamation marks or the word "major" when designing your prompt.

Could it be that longer chains are heavier and require more energy to move?

 

[Drago]

Could it be that longer chains are heavier and require more energy to move?

More inertial losses? Yes, but good luck trying to measure that outside of a laboratory.

For all practical intents and purposes the losses occur as the chain traverses the chain ring and cassette and the length of the chain has no bearing on that.

 

[Yellow Saddle]

Could it be that longer chains are heavier and require more energy to move?

Good question, let's analyse it. Yes, longer chains are heavier than shorter chains. Also objects only require energy to accellerate and during accelleration, more energy is required to accellerate something heavy than something light. Once something is up to speed, it requires no energy to keep moving, albeit we have friction robbing the constant speed of it's, well, constancy. So yes, heavier objects require more energy to keep going at a constant speed when cycling because uphills are technically accellerations. In space, once you've accellerated to speed, you stay there with no energy required. We don't cycle in space. It is cold there, and besides, it lacks the whole atmosphere of of cycling.

In reality, a 29-er may require two more chain links than a 26-er. I quickly measured 2 chain links and foud they weigh 16 grams. Therefore, the weight difference (calculated only by the effect provided by a longer chain) is 16 grams. A bicycle and rider weighs....say 80 kilograms if we're kind to the cyclist and his/her bike. 16/80 000 = 0.0002. The weight that you have to accellerate is 0.0002 times more for a 29er than a 26er. Conclusion? The difference is not "massive" as claimed.

However, the OP said, "major loss of energy". Clearly, we are not in the major ballpark. Further, the OP seems to think that the energy losses occur because of the increase in chain length. He/she didn't think this through. The "loss" (no energy is lost, BTW, because energy put into accellerating the heavier chain is returned when coasting) is nowhere near major.

Let's now assume the OP meant something difference - that the longer chain is somehow less efficient, as some posters upstream assumed, which I gauge from their answers, this is blatantly untrue. Efficiency is all about energy losses vs input. A longer chain has exactly the same energy losses in the chain as a shorter chain, if we use the same sprockets for both chains. Energy losses in a chain, as was pointed out upstream, are all about the amount of articulation a chain does around a sprocket. NOTHING ELSE. If a chain is long or short, if it runs over two sprockets of a given size for both scenarios, it loses the same amount of energy.

Energy losses in a chain are a function of sprocket size (the smaller the sprocket, the more arcitulation and therefore the more losses), lubrication and chain tension. More chain tension (harder pedaling) the more the losses. Better lubrication...well that's obvious, isn't it?

So no, heavier chains don't require more energy to move unless you consider 0.0002 significant.

 

[Mike Ayling]

It is "recent" for some of us. When I bought my 26" Thorn bike, they were extolling the virtues of the then "new" (at least for serious bikes) 26" wheels over the traditional 700C (which itself replaced the 27" of my youth) Seemingly 26" is now considered almost obsolute.

It seems smaller wheels were better, but nowadays bigger wheels are better !

Thorn are still offering 559 (26 inch) wheels on their tourer.

 

[Mike Ayling]

One thing that bugs me is why wheels aren't referred to by their actual size - the bead seat diameter (plus optionally rim width).

As far as I know "29 inch" wheels are actually 622mm, as are "700C". So two groups of cyclists have independently invented different stupid confusing names for the same thing.

I wouldn't mind if the confusing names were just names, like "Henry" or "Winkler". But they actually have a number in there that doesn't represent anything at all. Are 29" wheels actually 29"? Are 700C wheels 700mm? Ha! It depends what size tyres you fit, but the answer's almost certainly going to be "no, of course not". That's what makes them stupid as well as confusing.

Why?

Agree 100%!

 

[DRM]

For what it's worth, I remember reading in one of the MTB rags when 29ers first came out, they compared 26" to a 29" wheel stating they roll better over obstacles & are faster,etc,etc, with a graph showing time to ride a loop, with an exagerated line for speed for the 29er compared to 26", however the actual numbers suggested the difference was a fraction of a second, in my experience, my now elderly Cannondale SL3 MTB works just as well as they day it was bought, give it a few more years & they'll be extolling the virtues of nimble 26" wheels

 

[Drago]

For what it's worth, I remember reading in one of the MTB rags when 29ers first came out, they compared 26" to a 29" wheel stating they roll better over obstacles & are faster,etc,etc,

But only in ideal dry conditions, and even then the very marginal gains made on the straight are lost through accelerating the extra mass when moving off, of the slightly greater gyroscope effect when steering.

MBR, one of the more serious MTB periodicals, did their best to have nothing to do with 29ers for this reasons, only changing their stance when they became so ubiquitous that they had little choice.