Australian Cycling Forums - Bicycles Network Australia

Does anybody know with the same gearing what is the speed or rolling distance between a 26 and 29 wheels. I am involved in a local bike race (Barrow Island)with different size wheel sizes involved and it would be nice to be able to equaise the time results.

Not sure what youare asking. maybe

or

Circumference

A fast rider on a 26er will beat a slow rider on a 29er and vise versa.

Same rider different bikes. Depends on the terrain or the quality of the bike.

With a 29er you use a rear sprocket with 1 or 2 teeth bigger (use the gear calculator) than with a 26 inch bike for the same gearing.

ratio disscussion in this thread
Building a bike around a Niner One frame

I'm a little confused about what you're asking too. So I'm just going to throw the physics considerations at you and hope some of it sticks.

Gearing and Speed
With the bigger wheel size you'd just select a different gear, until you run out of gears at the low end. 29er wheels are roughly 11% bigger, which equates more or less to the difference between a 34T granny gear and 30T second gear on a 9-speed cassette. So unless you really need that granny gear (I did on the weekend) then there's no "conversion" to be done for speed on wheel size. Bigger wheel does not mean faster necessarily: read on!

So what difference does a bigger wheel make?
29ers lose less energy over rough terrain than the smaller wheels. This is due to the bigger hoops meaning you don't drop as far into the ruts in choppy surfaces and then waste energy coming back up. The reduced angle of attack over bumps means less of your kinetic energy is spent moving your mass up and down and it is instead preserved in forward motion. If you slip on a loose surface say while pedalling uphill out of the saddle, I've found they tend to regain traction more often.

However, on smooth terrain the momentum conservation advantage is neutralised, and if the track gets tight and twisty necessitating you getting on the brakes a lot to negotiate corners, the extra rotating mass in the big hoops and tyres becomes a disadvantage as you have to accelerate back up to cruising speed. Further, the taller front end usually means a higher centre of gravity, which slows steering response and requires more body english from the rider - even if you don't have to get on the brakes.

Conclusion
So whether a 29er is faster is terrain specific. After seeing my mate shave nearly 10 minutes off his best lap time by swapping to a 26er for his last lap of the Mont 24hr a couple of weekends ago, my views are now more fluid than they were and I'm questioning whether my next bike will still be a 29er.

trailgumby wrote: Conclusion
So whether a 29er is faster is terrain specific. After seeing my mate shave nearly 10 minutes off his best lap time by swapping to a 26er for his last lap of the Mont 24hr a couple of weekends ago, my views are now more fluid than they were and I'm questioning whether my next bike will still be a 29er.

How many people were on the track when he did his last lap. Two of my mates both shaved 5-6 minutes off their last laps at the Mont. One was on a 29er the other a 26er. From my experience at the Mont since 2003 the number of people on track holding you up has a far greater impact than what wheel size you are riding.

I think somwhere on the net there is a comparison with power meters that shows the 26er uses less power for the same speed. Therefore it should be faster. In saying that I still love my HT 29er and my 6in Dually 26er. I just need to start riding the 29er more like a hardtail and not like a dually to go faster.

The reason I asked this question is that I ride with other riders of the same abillity, but they always seem to just keep moving ahead now . A 11% difference between the size of the wheels is a bloody good excuse for me and so I can order a new 29 er with confidence

Thanks

Your next bike might be a 27.5 Gumby .

paul33 wrote:The reason I asked this question is that I ride with other riders of the same abillity, but they always seem to just keep moving ahead now . A 11% difference between the size of the wheels is a bloody good excuse for me and so I can order a new 29 er with confidence

Thanks

Don't see how it makes any difference.

44x13T 54 - 599 (26 x 2.0) at 90 rpm = 38.3 kph
and
44x13T 50 - 622 (29 x 2.0) at 90 rpm = 41.5 kph
but
44x12T 54 - 599 (26 x 2.0) at 90 rpm = 41.5 kph

So change gear!

Buying a 29er will not make you faster.

What RonK said. Change gear

29'er will be quicker on certain terrain compared to 26'er... always going to be a compromise... hence some pro riders with big budgets are experimenting with the 27.5'ers.
11%?... no.

Wouldn't the greater rotating mass make a 29er slower to accelerate?
Whether that's a disadvantage or not would depend on the trails of course...

Mulger bill wrote:Wouldn't the greater rotating mass make a 29er slower to accelerate?
Whether that's a disadvantage or not would depend on the trails of course...

Yes, and yes.

toolonglegs wrote:29'er will be quicker on certain terrain compared to 26'er... always going to be a compromise... hence some pro riders with big budgets are experimenting with the 27.5'ers.
11%?... no.

Ah, yes. 650B.

From what I hear it's the riders who are on the smaller side who are going for this option, because of the difficulties in getting their position on the bike sorted to their liking with a 29er. Usually it's because the bars are too high compared to the seat. From my limited experience with a 29er this made me feel like I was trying to negotiate a technical trail on clown stilts. Lowering the bars made a huge difference.

Maybe someone should bring out upside-down riser bars for 29ers?

trailgumby wrote:...snip...

Maybe someone should bring out upside-down riser bars for 29ers?

Just mount your current "riser" bars upside down?

What Emily has to do to make a 29er "fit". here sometimes a 650c or a 26er makes more sense.

mitzikatzi wrote:

trailgumby wrote:...snip...

Maybe someone should bring out upside-down riser bars for 29ers?

Just mount your current "riser" bars upside down?

Ends where the grips are still need to be angled up to be wrist-friendly.

Hmmm, I looked at the Anthem 29er when I went to a dually but there was no way ol' stumpylegs would ever get comfotable without a leaning backwards position. 650B might be worth a hardtail look.

trailgumby wrote:

mitzikatzi wrote:

trailgumby wrote:...snip...

Maybe someone should bring out upside-down riser bars for 29ers?

Just mount your current "riser" bars upside down?

Ends where the grips are still need to be angled up to be wrist-friendly.

I should have known it was not that simple. I thought I have read of short people mounting bars upside down to make 29ers fit maybe it was just the stem.

There are a couple of 650s dual suspension bikes. A big 650c thread on mtbr.

The cycling here on Barrow Island is a combination of road and dirt road riding, we are not allowed to go off road as its an A class reserve. Parts of the road are corrigated and the "huge mountains" here are a maximum of 60m above sea level.
With this conversation I think I have 2 main problems 1. Falling into the corrigations will slow the wheels down and 2. like all cyclist not enough legs

Thanks for all your help

paul33 wrote:1. Falling into the corrigations will slow the wheels down and 2. like all cyclist not enough legs

Thanks for all your help

Sounds like 29er country to me - bigger wheels = bigger holes you can roll over, no climbing means no worries about acceleration. If you only have room for a single MTB then I still think a 26er is more versatile - the 29ers to me feel just a bit too unwieldy in the sketchy/tight/jumpy stuff but I am a complete MTB gumby. Just after I finished building up a (smaller) blue Apollo 26er hardtail I was amazed at just how alive that bike was compared to my usual ride...and I liked it a lot. There's a lot to be said for smaller, more agile mountain bikes.

drubie wrote:There's a lot to be said for smaller, more agile mountain bikes.

Some of the more gravity oriented guys in my area tend to opt for smaller frames deliberately for this reason, they're a lot easier and more nimble to handle on techy descents.

i have a 26er HT and a 29er duallie and they are like chaulk and cheese. i haven't gotten used to flicking the 29er into corners - keep running wide, not just as it steers slower, but as the bigger wheels seem to push out wider as you lean in around your CoG.

however, out at the You Yangs yesterday, i was really impressed with the 29er coming down black diamond runs over rocky descents - just ate them up, whereas i know my 26er (HT) would be trying to kill me. partly that's probably the dual suspension helping - but the big wheels certainly eat up rocks and other obstacles.

@jules: have you tried getting the bars as low as possible on the 29er? Makes a big difference I've found.

To the OP, another angle that I don't think has been raised.

Power output: To a large extent your power output will be static. So the gear ratio/cadence you have use on your 26er, will be different combo on your 29er, BUT on average your overall speed would be comparable.

anything designed for XC with 100mm of travel, 29er all the way. Epics and stumpy HTs maneuver so well i reckon. very little diff between a 26er. the more travel the more inclined i would be to to go 26 just to get a bit more maneuverability. not sold on camber and stumpjumper fsr 29ers...or for that matter anthem X due to its apparent longer chainstays, but will test ride one in a month.

29ers don’t. Just a fad. Don’t ask anyone who owns one because their opinion of their own bike over something someone else is riding would be obvious. They’re now preferred by taller riders because the compromise in frame geometry to fit the larger wheels don’t adversely affect handling as much in the larger frames as it does in the smaller frame sizes XS~M, but that’s like saying gonorrhoea is the best of all the sexually transmitted diseases.

29ers are good for those who upgrade often, as it will fit in nicely when in 2013~14 the US brands trot out something new.

But please, Don’t hate me for my opinion.

Hence 650 / 27.5 is on the way

Marx wrote:29ers don’t. Just a fad. Don’t ask anyone who owns one because their opinion of their own bike over something someone else is riding would be obvious. They’re now preferred by taller riders because the compromise in frame geometry to fit the larger wheels don’t adversely affect handling as much in the larger frames as it does in the smaller frame sizes XS~M, but that’s like saying gonorrhoea is the best of all the sexually transmitted diseases.

29ers are good for those who upgrade often, as it will fit in nicely when in 2013~14 the US brands trot out something new.

But please, Don’t hate me for my opinion.

Thats right, don't ask for an opinion on a bike from someone who actually owns one, instead ask someone who thinks they know
what they are talking about but clearly have no idea.