I read that 29ers keep speed up better and 27.5 accelerate better. Am I correct in inferring that 27.5 are thus better for trails with a lot of long, and often steep climbing. I would think on long, tough climbs the 27.5 would be easier to keep moving. Is this true?
Are 27.5 better for climbing than 29 inch wheels?
1 reading
joevdenne
41 - 60 of 68 Posts
That's a killer course.
Same Bike, swap wheels
For example, take a Santa Cruz Hightower and swap wheel sizes that have same rims and exact same tires. Then you only have to factor in the increased weight of the 29ers.
Stop muddying the waters guys, you have to compare similar setups.
For example, take a Santa Cruz Hightower and swap wheel sizes that have same rims and exact same tires. Then you only have to factor in the increased weight of the 29ers.
Pass Steel Calf the deagle
Somebody pass this man the deagle. He is clearly a legendary eagle.
Joined
·
554 Posts
My .02. I'm a better technical climber on my 27.5 intense spider than I was on my previous bike, a Pivot 429. I feel faster on smooth climbs, especially on switch backs and uphill corners, but I don't time myself so who knows for sure.
Joined
·
1,301 Posts
I think it all comes down to tire selection. Currently many of the enduro and DH tires were developed on 27.5" rims and have the knobs needed to grip on an enduro climb. I would venture to guess that 27.5 enduro and dh bikes climb better than 29ers. The 29" tires were developed in XC racing. They are generating the minimum rolling resistance with just enough traction to climb. I would venture to guess that these 29" bikes out climb the 27.5" bikes anywhere traction is at a premium because they were designed around a 29" wheel and not a 27.5" wheel. I'm sure a modern version of a fire XC pro can climb like a rocket ship on a 26" bike. It just doesn't have the past 10 years of tire technology dumped into it.
Joined
·
5,798 Posts
Joined
·
445 Posts
When traction is good and not too bumpy, my 650b seems to spin up the hills maybe a little easier. As soon as it's slippery or roots, the 29er wins.
The scientific answer has to be "what McMick said".
Anyone here with a Hightower or similar switchable bike done the needed experiment yet?
Contrary to the labeling convention of 26", 27.5" and 29" wheels, the difference in wheel sizes between 26" and 27.5" is about half of the difference between 27.5" and 29".
So a better intermediate rim size might have been the old 590mm size as used on 3-speed "upright touring" bikes back in the day.
But of course the tire width and pressure plays a big role in how well these sizes work in different environments.
Anyone here with a Hightower or similar switchable bike done the needed experiment yet?
Contrary to the labeling convention of 26", 27.5" and 29" wheels, the difference in wheel sizes between 26" and 27.5" is about half of the difference between 27.5" and 29".
So a better intermediate rim size might have been the old 590mm size as used on 3-speed "upright touring" bikes back in the day.
But of course the tire width and pressure plays a big role in how well these sizes work in different environments.
Joined
·
445 Posts
I was looking at the Stans site recently. Rim weight different for the same model was about 30-50 grams between 27.5 and 29, depending on the model. I’m guessing there might be similar weight savings in the rubber. So maybe 60-100 grams of rotational mass savings per wheel for an otherwise identical wheel setup. 120-200 for a pair. Then there are the physics of rotatating that around a smaller radius which will help the acceleration. Of course you are losing some traction. But, let’s think about a long, 7 mile, fairly smooth dirt road with some good traction. Or think about a marathon race with 12k ft of climbing on similar roads. I’ve got to think that weight plus rotational savings would add up to something. Probably not enough for the average trail rider cover 10-20 miles.
Then to make up for traction, the 27.5 either needs a wider rim/tire or both, so you give back the outright weight advantage.
I think it comes out in the wash for most people. I would would just go for the best deal on the highest end, lightest, best fitting bike you can afford. Wheel size is just one part of the total bike setup, and you can play with tires and rims to help with any traction issues.
Oh wait, and I forgot rollover.....
Then to make up for traction, the 27.5 either needs a wider rim/tire or both, so you give back the outright weight advantage.
I think it comes out in the wash for most people. I would would just go for the best deal on the highest end, lightest, best fitting bike you can afford. Wheel size is just one part of the total bike setup, and you can play with tires and rims to help with any traction issues.
Oh wait, and I forgot rollover.....
Joined
·
14,627 Posts
You also forgot:
Crr. Coefficient of rolling resistance. There's a reason every World Cup racer over 5'4" is racing a 29er, despite many of them having an option to use a 650b bike.
If people whose livelihood depends on going up (and down fast) are using a heavier bike, maybe there is something to that.
Sent from my XT1585 using Tapatalk
Joined
·
302 Posts
I have both a 29'r and 650B+ wheel setup for my Canfield Riot. Times are pretty much a wash on my climbs. I run the same gears on both setups and typically end up being more tired at the end of the ride on the 29's because of the increase in gear inches. I usually have to be in the bailout gear more often because of this also. I can climb everything on both. I will say that on more than one ultra steep climb I have wheelied out using the 27.5x2.8 tires where the 29x2.3's would just loose grip. Falling forward because of lost grip sucks, but is manageable. Falling backward on a steep climb is dangerous and pretty much uncontrollable. But that's all rider error (me), and really not a problem with the bike or wheel size.
About a year ago I would have thought that 29ers would be faster climbing and 650bs would be better for descending. Now that world cup downhill riders are riding 29ers it seems to me that 29ers might be faster for just about everything. I still ride a steel 26er and my next bike will probably be a steel 29er.
Joined
·
4,610 Posts
Santa Cruz 5010 v.3, rigid single speed karate monkey
Joined
·
4,948 Posts
i'll second that. i am (was, will be) slower on my thirty one pound 27.5 dualie than on my twenty nine 29er hardtail because i am (and will be) totally out of shape.
Joined
·
8,066 Posts
Besides physical ability, the bike geo and setup will make the biggest difference.
I have a 29r HT that weighs 19.7lbs and a 27.5 FS that weighs 30.5lbs. I can climb a heck of a lot faster on the 29r than the 27.5...and I'm pretty sure it's not the wheel size that's slowing me down. The 29r is pretty much a straight XC bike. The bar is much lower and over 10lbs lighter than the 27.5. The XC bike with the low front end feels like I can just bury my head and crank up the hill.
I have a 29r HT that weighs 19.7lbs and a 27.5 FS that weighs 30.5lbs. I can climb a heck of a lot faster on the 29r than the 27.5...and I'm pretty sure it's not the wheel size that's slowing me down. The 29r is pretty much a straight XC bike. The bar is much lower and over 10lbs lighter than the 27.5. The XC bike with the low front end feels like I can just bury my head and crank up the hill.
Joined
·
1,301 Posts
Considering Nino was hacking up treads and gluing them to tubulars I don't think that is too far fetched. He was literally using custom made tubulars to race on. His very own custom made tubular semi slick for XC racing. Everyone else is on tubeless 29er tires but he is running custom 27.5 tubulars. Winning races too.
Joined
·
4,610 Posts
Schurter switched to 29 midway through the World Cup season last year and Scott mechanics have worked hard on adjusting the geometry of the bike to accommodate his very peculiar cockpit set-up. He runs a 90mm stem with a negative rise to keep the handlebars really low. The previous 29ers had too much stack height.
He also ran tubeless for the last year and a half. He had his best ever year on a tubeless 29er.
https://www.bikerumor.com/2016/07/0...ck-repeat-elite-mens-world-champion-nino-schurter-on-new-scott-spark-rc-900-wc/
Joined
·
2,607 Posts
Well, this isn't a climbing test, but the 29er was faster than the 27.5" here. (I love videos like this that for sure just piss off mtb makers at Giant). Should be interesting to watch their upcoming tests on the two wheel sizes.
https://m.pinkbike.com/news/which-wheel-size-is-faster-with-vanderham-and-gauvin-video.html
https://m.pinkbike.com/news/which-wheel-size-is-faster-with-vanderham-and-gauvin-video.html
Joined
·
2,607 Posts
And another recent test showing 29ers are faster than 27.5", although not sure there is climbing involved.
Pretty interesting too considering there was only three 29ers and seven 27.5 bikes in the test and...
"...there were clear tendencies. All three testers rode their fastest times with 29″ bikes and the slowest on 27.5″ bikes."
Let's go Racing! - The 10 fastest enduro bikes in test | ENDURO Mountainbike Magazine
Pretty interesting too considering there was only three 29ers and seven 27.5 bikes in the test and...
"...there were clear tendencies. All three testers rode their fastest times with 29″ bikes and the slowest on 27.5″ bikes."
Let's go Racing! - The 10 fastest enduro bikes in test | ENDURO Mountainbike Magazine
41 - 60 of 68 Posts
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
