27.5 vs 29 in 2021

mathewdavidbrown

Hi guys. A question which doesn't get asked frequently enough in my opinion. Most videos and forum threads addressing it seem to be a few years old.

Anyhoo. I've been saving hard for an enduro-esque trail bike and I want something which is going to be future-proof. With 29 inch wheels steadily becoming the default size, is it likely 27.5 will virtually disappear like 26 did? Of course there's shorter riders to consider, but will the 29er geometry wizards figure a way around that too?

Just after some thoughts really.

Thanks

reaperactual

Not everyone has a 29er, I like 27.5 and will continue to choose 27.5, nothing to do with my height.

I will go to a big, gangly, floppy 29er if I have to.

Maybe that will be after there is literally nothing else except 29" to choose from. 🪙🪙

mathewdavidbrown

reaperactual said:

I will go to a big, gangly, floppy 29er if I have to.

Maybe that will be after there is literally nothing else except 29" to choose from. 🪙🪙

That's my worry. I'd much prefer a 27.5 but I don't want to buy one if they're about to fade into obscurity.

steve_sordy

The next big thing is "Mullet" bikes. ie 29 front 27.5 rear. This gives you the roll over capability of the 29" wheel, without your rear end being buzzed when you are descending steep stuff.

While undoubtedly a 29" wheel is less stiff than a 27.5" wheel given the same rim section and number of spokes, stiffness by itself is not necessarily the best criterion to choose a wheel. Some compliance gives a smoother ride and knocks less out of the rider. Yes the wheel is heavier and takes marginally longer to accelerate, but they roll over stuff better, much better, and they carry speed better. I have had 26ers, 27.5ers, 29ers and now a mullet. Overall my favourite has to be the mullet.

I doubt that the 27.5" wheeled bike will disappear any time soon. Rest assured that there will be forks and wheels available for years to come. You can still get stuff for 26ers and that was a wheel size that should have gone years before it did.

reaperactual

mathewdavidbrown said:

reaperactual said:

I will go to a big, gangly, floppy 29er if I have to.

Maybe that will be after there is literally nothing else except 29" to choose from. 🪙🪙

That's my worry. I'd much prefer a 27.5 but I don't want to buy one if they're about to fade into obscurity.

There are less riders choosing 27.5" over 29er. Most of my Pals are still on 27.5 and don't plan to change any time soon.

Maybe 27.5 is in the minority nowadays but I agree with Steve they will be around for a long time.

My next bike will be a 27.5 and I ain't worried about going that route for the foreseeable future.

Have noticed a few brands don't have a 27.5 option anymore or have 27.5 for smaller frame sizes and 29 for M,L,XL.

Your choice of course but if you want a 27.5 then go for it as maybe you won't have a choice but to buy a 29er the next time you're after a new bike?

If I had to buy a 29er right now the mullet option does sound tempting and wouldn't mind that set up as a 'best of both' option.

mully79

Im still using 26" and have been sitting on the proverbial fence since 2014 which looks silly now as its been 7 years. Most likely the bike will be worn out before either 27.5 or 29 dies out whichever you buy.
Agree with the posts above so waiting for the right mullet option for me now

mathewdavidbrown

I'm intigued by the mullet. My only issue is the longer chainstay on bikes which take both size rear wheels, and I'd imagine pure mullets still have longer chainstays to counter the front wheel. It's the idea of 'sitting on top of the bike' that puts me off the 29er.

I'd prefer a 27.5, but I want this bike to be like Trigger's broom - whereby every element can be swapped out and replaced year after year, so I wouldn't have to buy a new bike. A new wheel size means new mostly everything. Buying a 26er in 2014 wouldn't have been a good idea in this respect. Feasible, but hella awkward.

Mad_Malx

Cannondale did a rigid 26/24 in the 1980s that was popular with London couriers. First factory MTBs I remember noticing (although I had a suspension fork frankenbike in the early 1970s).

Bring back the penny farthing!

Mad_Malx

Does the geometry change much if you just slap a 27.5 on a 29?

mathewdavidbrown

Mad_Malx said:

Cannondale did a rigid 26/24 in the 1980s that was popular with London couriers. First factory MTBs I remember noticing (although I had a suspension fork frankenbike in the early 1970s).

Bring back the penny farthing!

Christ, and I thought I was a dinosaur!

Just joshing :-D

I guess the bottom bracket would drop down a smidge.

steve_sordy

Most 27.5" wheels measure just over 27" with the tyre on, whereas the 29ers actually do seem to measure 29" or slightly more. So the drop in diameter is more like 2", not 1.5". The actual drop will be half that, so one inch.
The BB is approx one third of the wheelbase away from the rear axle on a large bike, (further on a small bike, less on a bigger bike).
So the drop at the BB will be one third of an inch or 8.5mm.

That drop will lower your centre of gravity, make you feel more in the bike than on it, but you will get an increase in pedal strikes until you get used to it.

That one inch drop at the rear axle will reduce your head angle by 1.2 degrees. this will feel better descending but may completely screw up your climbing.

mathewdavidbrown

I understand 29ers are a different ride from the 27.5, and I could probably get used to the larger wheel size, especially with the geometries becoming ever more agile, but I'd still prefer a snappier 27.5.

It's the commercial longevity of the 27.5 wheel which bothers me. I've been saving for years and am not likely to afford a whole new bike ever again, so I want a Trigger's broom, in which I can swap out the wheels one year, change the frame the next, then new forks, etc. But for this to work I need an initial bike which will still be in line with industry standards for a good few years.

I realise no one has a crystal ball here, I'm just curious what other people think.

mully79

The wheel size themselves is the least of your problem with longevity.
Bike manufacturers make money selling bikes not on how long they stay current.

Choose from the current standards;
Standard shimano hub, shimano microspline or sram xd.
Standard derraileur hanger or new sram universal hanger.
6 bolt or shimano centrelock rotors.
Post or flat mount callipers.
Seatpost diameter x many stealth or exterior?
Super boost, boost, 135mm 142mm rear axles.
15mm or 20mm or other proprietary front axle in boost or non-boost.
Boost or non-boost cranks
Headset/fork compatibility 1.5 for every possibility or tapered ?

steve_sordy

mathewdavidbrown said:

............... It's the idea of 'sitting on top of the bike' that puts me off the 29er. ................

29ers have the bottom bracket positioned below the centreline of the wheels to ensure that people are not "sat on top of the bike". I suspect that early 29ers were simply 26ers with everything sized up to ensure bigger wheels fitted, but without thought to the overall geometry. Those early bikes gave rise to sayings like "on the bike, not in it" and "steers like a barge" for example. Neither of those are true today, unless it's an old bike!

Modern 29er geometry is light years away from the early versions. If you were to go try a few recent bikes, I'm sure that your concerns will be set aside.

However, lets be clear, a large size 29er full suss will never be as nimble as my grandson's 24" rigid. He could thread his way through closely spaced trees like he was a rat fleeing from a cat posse. His narrow bars may also have had something to do with it.

pep.fermi

Last year I bought a used full carbon MTB with Shimano GRX for a ridiculous 280eur. OK, it was 10yr old, in theory at least, in reality it was never used. A new bike with these specs would have costed almost 5k. The shop said that years ago the industry moved to 29", so prices of the old 27" standard went to zero.

You sure you want 29"?