# Mountain tandem 29er vs 27.5???



## alien too (Mar 4, 2008)

I was looking for advice on which wheel size I should go with.
I will be doing marathon races on it.


----------



## Hurricane Jeff (Jan 1, 2006)

If I were building a custom or had a choice of tandems with each wheel size, I'd go with the 27.5" size. I ride a 27.5er single bike and am totally sold on the size. With a tandem, you already have slow steering in which a 29" wheel is just going to make it even handle slower.
On my Ventana El Testigo, it has sliding rear dropouts that can accommodate 27.5" wheels, just need a fork to seal the deal.


----------



## ds2199 (Sep 16, 2008)

*Wheel size on a tandem*



Hurricane Jeff said:


> If I were building a custom or had a choice of tandems with each wheel size, I'd go with the 27.5" size. I ride a 27.5er single bike and am totally sold on the size. With a tandem, you already have slow steering in which a 29" wheel is just going to make it even handle slower.
> On my Ventana El Testigo, it has sliding rear dropouts that can accommodate 27.5" wheels, just need a fork to seal the deal.


I will add that having a larger diameter front wheel is a big deal relating to a tandem mountain bike. Way moreso than a single bike. I would agree that 27.5 might just be the perfect balance of wheel sizes for single mountain bikes, but for a tandem, where you can't lift the front wheel, the larger diameter wheel (29") has an advantage. Slower handling may be a consequence of riding larger wheels, but I'll take the trade off so that we can roll over certain obstacles that were problematic on the 26" wheels.

To be clear, I don't think there is a "right answer", only personal preferences. For the riding that we do, even if I had a blank slate and were building a new custom tandem, *I would certainly choose a 29" front wheel *and likely the rear wheel as well (but I suppose 27.5 would be just fine).

For reference, we have owned 26" Ventana ECDM, 29" Fandango and 29" Ventana ECDM.


----------



## Hurricane Jeff (Jan 1, 2006)

The rollover of a 29er wheel and all the subsequent info about the bigger wheel being faster is only partly true(trust me, I've done my experiments on single bikes).
While true, on a tandem, your not easily going to lift the front wheel over obstacles, your either going to unweight the front end as much as possible, or just ram into them.
I would never ride an off road tandem with nothing less than 5" travel fork, preferably 6"+, so the fork takes up a lot of the impacts.

In my testing on wheel size, while not totally scientific, my results had the 27.5" wheels faster in just about any condition, the only area that the 29er was or seem faster was on climbs with "baby head" sized rocks.
I've been in way too many discussions on this and was told that there is no way it could be this way, "because bigger is always better" i was told, my findings have found otherwise.
I'm not trying to start a debate into which wheel size is best, your results may vary, just thought I'd share my results.


----------



## ds2199 (Sep 16, 2008)

Hurricane Jeff said:


> The rollover of a 29er wheel and all the subsequent info about the bigger wheel being faster is only partly true(trust me, I've done my experiments on single bikes).
> While true, on a tandem, your not easily going to lift the front wheel over obstacles, your either going to unweight the front end as much as possible, or just ram into them.
> I would never ride an off road tandem with nothing less than 5" travel fork, preferably 6"+, so the fork takes up a lot of the impacts.
> 
> ...


Good info. I'm not interested in a debate either.

FWIW, I don't ride trails that would require a 6" travel fork, nor could I even stand over such a bike if it had 29" wheels.

What I like about this forum, is hearing advice from real world users.

Someday, maybe I'll get to ride a 27.5 tandem and have a real comparison. In the meantime, I'll live vicariously through those who have.

I do agree about unweighting the front end of the bike and I know it flat out works better with the 29" wheel vs. 26" wheel. I have no real world experience with the 27.5 on a tandem.


----------



## Hurricane Jeff (Jan 1, 2006)

ds2199, neither do I have the experience riding a 27.5" or 29er tandem. All my tests have been done on single bikes, in which I own at least one bike of all 3 sizes.
I have found the 27.5" bike to be better is just about any situation.
My Ventana El Testigo has sliding rear dropouts, which can accommodate a 27.5" wheel, I would still need a fork that would work on that size to make it work, which I hope to do soon.


----------



## ebnelson (Oct 30, 2006)

alien too said:


> I was looking for advice on which wheel size I should go with.
> I will be doing marathon races on it.


Front suspension or full suspension? In my opinion the 29er is best for both, but for a hardtail the 29er even more so. We have been using the Ergon CF-3 on the road bike to smooth out the stokers ride. I used to use this seatpost on my hardtail single and loved it. Our marathon racing tandem would be a 29er HT with CF-3 seat post and some sort of high range 2x10 or 11 gearing. Our ECDM FS 29er is built up and reliable at 42lbs. It could be a couple pounds lighter with the right parts. A carbon HT could easily loose 5lbs over the aluminum FS.


----------



## PMK (Oct 12, 2004)

There are a bunch of various factors and really it does just depend.

The biggest factor is the terrain and local riding. These are where the decisions are made, but what works for one on the West Coast, may fail on the East Coast, yet be better in those Colorado mountains. 

Also, the riders themselves have a lot to do with it.

Really it does just depend.

PK


----------



## mactweek (Oct 3, 2011)

I'd like to see a tandem that could take 29 x 3" knards or maybe the upcoming wtb 27.5 x2.75 tires that are coming soon. I love the rollover on these fatter tires and more rubber on the ground is a good thing. You could also run a bit less tire pressure which gives a hardtail a better ride.


----------



## TandemNut (Mar 12, 2004)

I think the thing most folks don't take into account in the newest, best-ever, end-all wheel size of the month is that the relative weight and wheelbase of a tandem is roughly 1.5 or more times that of a single. Both factors, from a physics standpoint, would favor bigger wheels. 
We've ridden 27.5" and 29" ECDM's back-to-back on the same trail, and the 29'er is smoother, and seemed faster, or it seemed that we weren't working as hard. We will do the same experiment on a more technical trail, which might favor the 27.5. 
In most real-world settings, I believe bigger is better, provide the geometry is designed around the challenges associated with the respective wheel size.
And yeah, I've been thinking about a Fandango version that would run the Knards and other 29x3.0 tires. That would be cool!


----------



## rockman (Jun 18, 2004)

Resurrecting this old thread. I'm giving up the ghost on my old 26" Santana Rio and I'm curious now 6 years later if this thread is still relevant wrt wheel size.

Having had a El Saltamontes and El Ciclon a decade or so ago, I'm thinking about a Ventana ECDM. I still ride a 27.5 Turner RFX but love my 29r Evil Offering. I get the point in this thread about rollover with the bigger wheels but maybe 27.5+ might be more maneuverable on techy trails. Can you run both wheelsets on a ECDM with a 29" fork? Any feedback appreciated.


----------



## ebnelson (Oct 30, 2006)

rockman said:


> Resurrecting this old thread. I'm giving up the ghost on my old 26" Santana Rio and I'm curious now 6 years later if this thread is still relevant wrt wheel size.
> 
> Having had a El Saltamontes and El Ciclon a decade or so ago, I'm thinking about a Ventana ECDM. I still ride a 27.5 Turner RFX but love my 29r Evil Offering. I get the point in this thread about rollover with the bigger wheels but maybe 27.5+ might be more maneuverable on techy trails. Can you run both wheelsets on a ECDM with a 29" fork? Any feedback appreciated.


The bike can fit 27.5"x2.8" and up to 29"x2.6". The 29 option gives a bit more pedal clearance and the 27.5" option has a bit lower center of gravity for stability. We use 29"x2.6" for clearance, but it comes down to where you will be riding and also what standover height works for your team.


----------



## rockman (Jun 18, 2004)

ebnelson said:


> The bike can fit 27.5"x2.8" and up to 29"x2.6". The 29 option gives a bit more pedal clearance and the 27.5" option has a bit lower center of gravity for stability. We use 29"x2.6" for clearance, but it comes down to where you will be riding and also what standover height works for your team.


Thanks for the reply! Maybe I'll stick with the idea of having two wheelsets then especially if there is no difference in frame geometry with regard to wheel size. And perhaps over-fork it with a 150 for ramming over obstacles. Trails are rocky in my neck of the woods. Lots to ponder on a 70" wheelbase bike.


----------



## preventec47 (Oct 31, 2020)

I want to say that I think it is stupid beyond belief to take a stoker for a ride on any kind of rough trail with any kind of tandem. . There are a lot of MTB tandems that have borrowed the suspensions from single bikes and they look pretty cool and the suspensions could be useful but dont EVER try to go where the single guys go. I for one have an 18 yr old MTB tandem with 26 x2.4 tires at 35 psi and believe it is the greatest thing since sex for the urban bombing that I do with a stoker. Small pot holes, bumps,
uneven sidewalks, curbs etc etc. ( coming off them mainly..... if I am going up a curb it is at only about 2 or 3 mph where I climb the curb instead of impacting it...... All this said, I know I would salivate with even fatter and larger 27.5 or 29 wheels and tires. I am very very cautious about what risks I expose my stoker to. As if they have a pistol pointed at my head if I ever dump em.


----------



## rockman (Jun 18, 2004)

preventec47 said:


> I want to say that I think it is stupid beyond belief to take a stoker for a ride on any kind of rough trail with any kind of tandem. . There are a lot of MTB tandems that have borrowed the suspensions from single bikes and they look pretty cool and the suspensions could be useful but dont EVER try to go where the single guys go. I for one have an 18 yr old MTB tandem with 26 x2.4 tires at 35 psi and believe it is the greatest thing since sex for the urban bombing that I do with a stoker. Small pot holes, bumps,
> uneven sidewalks, curbs etc etc. ( coming off them mainly..... if I am going up a curb it is at only about 2 or 3 mph where I climb the curb instead of impacting it...... All this said, I know I would salivate with even fatter and larger 27.5 or 29 wheels and tires. I am very very cautious about what risks I expose my stoker to. As if they have a pistol pointed at my head if I ever dump em.


LOL, are you serious? Maybe it's the captain choosing a poor line. Tandems are rad.


----------



## longpete (Mar 30, 2021)

For the moment I'm testing mullet setup on our tandem. First impressions : positive.


----------



## mactweek (Oct 3, 2011)

We mulletized our old 26" Curtlo hardtail last fall. Did not get to do more than a couple shakedown rides, but first impressions are very good. We needed more pedal clearance, which was supplied by the White brothers fork, and 29/ 27.5 tires. Steering feels better with the new set-up as well.


----------



## R.T.R. (Sep 20, 2005)

preventec47 said:


> I want to say that I think it is stupid beyond belief to take a stoker for a ride on any kind of rough trail with any kind of tandem. . There are a lot of MTB tandems that have borrowed the suspensions from single bikes and they look pretty cool and the suspensions could be useful but dont EVER try to go where the single guys go. I for one have an 18 yr old MTB tandem with 26 x2.4 tires at 35 psi and believe it is the greatest thing since sex for the urban bombing that I do with a stoker. Small pot holes, bumps,
> uneven sidewalks, curbs etc etc. ( coming off them mainly..... if I am going up a curb it is at only about 2 or 3 mph where I climb the curb instead of impacting it...... All this said, I know I would salivate with even fatter and larger 27.5 or 29 wheels and tires. I am very very cautious about what risks I expose my stoker to. As if they have a pistol pointed at my head if I ever dump em.


Love ripping the Kenai Mt Alaska single track on my tandem, same trails I ride my singles on .. guess I'm stooopid beyond belief 🙄


----------



## ChargersWI (Nov 9, 2016)

That is great! My stoker wife likes/tolerates the single-track off-road trails while I really like them. Good pictures there.


----------



## Adventure-Biker (Feb 2, 2006)

ChargersWI said:


> That is great! My stoker wife likes/tolerates the single-track off-road trails while I really like them. Good pictures there.


LOL same here!!!! Hahaha


----------



## Adventure-Biker (Feb 2, 2006)

preventec47 said:


> I want to say that I think it is stupid beyond belief to take a stoker for a ride on any kind of rough trail with any kind of tandem. . There are a lot of MTB tandems that have borrowed the suspensions from single bikes and they look pretty cool and the suspensions could be useful but dont EVER try to go where the single guys go.


Speak for yourself! Aside from "log-over" crossings and similar rock crossings etc. where lifting the front wheel isn't possible and boom tube clearance may be an issue, there isn't really anywhere a single can go that our tandem can't - up, down, or tight.

This is us riding some tight singletrack in our home state of Florida. The trail in this video is actually tighter and a bit more technical than it appears in the video. We go through there a bit slower than I would on my single but the tandem handles it like a boss!


----------



## Adventure-Biker (Feb 2, 2006)

We have 2 tandem MTB's, both with 26" wheels. One is full rigid and the other full suspension. The rigid bike is more of a hybrid that I've basically converted for use as an MTB and as such is quite capable. Also have a 700c road tandem. We haven't ever ridden a 27.5 or 29er MTB tandem. I get the point(s) about rollover etc, but as someone said earlier I think a long travel suspension (at least up front) is WAAAAY more important on a tandem MTB than a bigger wheel size. By a long shot. Tandems are already slow handling beasts due to their length and the weight of 2 riders and anything that detracts even more from the handling is a bad idea. Of course the type of terrain you ride is a factor as some terrain & trails are less technical than others.

If you have a long travel suspension (our F/S has 170mm max set at 150mm travel up front and 120mm rear), you can set the fork with additional sag allowing it to sit deeper into its travel. This approach has worked beautifully on the twisty and rooty local trails we ride with our F/S. The bike handles well (as well as a tandem can), and the fork (and rear end) is very responsive in soaking up whatever roots etc I bash it into. By comparison, we have to slow way down - I mean way, way down - when we try to ride the same trails on our rigid 26er. It just can't go over the roots etc the same or as well. Its like night and day difference. Some of the more technical spots we even have to get off and walk the rigid bike through whereas we just easily roll right on through on the F/S. So in conclusion (and just my opinion), suspension is way more important (and critical) on a tandem than wheel size.

Our road tandem with 700c x 28 tires (essentially the same 622mm dia rims as a 29er MTB wheel), this bike goes great at speed and in straight(er) lines but slow speed handling and maneuvering (like you'd do on a MTB) isn't nearly as good or responsive as our 26" MTB's, even despite the F/S MTB having a longer wheelbase than the road bike. Even coming into corners at speed on the road the MTB tandems handle better (quicker & more precisely) and are more confidence inspiring in corners than the road bike.


----------



## TandemBear (Aug 18, 2013)

preventec47 said:


> I want to say that I think it is stupid beyond belief to take a stoker for a ride on any kind of rough trail with any kind of tandem. . There are a lot of MTB tandems that have borrowed the suspensions from single bikes and they look pretty cool and the suspensions could be useful but dont EVER try to go where the single guys go. I for one have an 18 yr old MTB tandem with 26 x2.4 tires at 35 psi and believe it is the greatest thing since sex for the urban bombing that I do with a stoker. Small pot holes, bumps,
> uneven sidewalks, curbs etc etc. ( coming off them mainly..... if I am going up a curb it is at only about 2 or 3 mph where I climb the curb instead of impacting it...... All this said, I know I would salivate with even fatter and larger 27.5 or 29 wheels and tires. I am very very cautious about what risks I expose my stoker to. As if they have a pistol pointed at my head if I ever dump em.


You mean like this?









Perhaps you could just realize that everyone is different and has different levels of risk. My intrepid stoker is a former ski racer, rock climber, etc., so she probably thinks this is no big deal. Where's the cliff? No thousand foot drops?

I do commend you though on not wanting to risk scaring, injuring or doing worse to your stoker. That's an excellent approach.

But just know that mountain biking aggressive terrain on a tandem is so much fun for many of us.
PS Can't WAIT to add a Ventana FS tandem to the stable. Taking today's 29" wheel full suspension geometry up to Tahoe will be awesome.
PPS Have attempted Moab's Slickrock Trail twice with complete rear hub failure. Rode it briefly in '16, but not the entire loop. Still on the "to-do list!"


----------



## ChargersWI (Nov 9, 2016)

TandemBear said:


> You mean like this?


That is awesome! I love it when I see tandems doing stuff that people think only singles can do.



TandemBear said:


> Perhaps you could just realize that everyone is different and has different levels of risk.


Agreed. My wife/stoker is up for off-roading. Great; we'll do some. But she doesn't want the gnarly stuff that some others are comfortable with. That's okay; we'll just not go that far.


----------



## TobyGadd (Sep 9, 2009)

preventec47 said:


> I want to say that I think it is stupid beyond belief to take a stoker for a ride on any kind of rough trail with any kind of tandem.


Every tandem couple has a unique combination of compatibility, skills, risk tolerance, trust, coordination, etc. My wife and I have really learned to ride TOGETHER--so I'm not "taking" her anywhere. Rather, we are working the bike together, which makes for some amazing rides. Yes, I have the responsibility of not picking terrible lines or sending us off a cliff, but she is far from a passive participant. Since we're both capable solo riders, we both know what it takes to make a bike work. A trick that she learned is to think of her hands being on my bars, which allows her to effectively move her weight around to match the trail. The more synchronized we are, the more we enjoy technical rides.

That said, if you believe that you "take a stoker for a ride," then you probably don't want to try anything very technical. For example, I would never choose to ride something more technical than a paved bike path with my mother! I would also be extremely careful riding with a kid, at least until they developed solid solo skills.

But back to the original question: I really like our 29er. While we can unweight the front wheel a little bit, having wheels that more easily roll over stuff is good. A Thudbuster for the stoker is also helpful, since she simply can't anticipate everything that we're going to hit--and tandems seem to "leverage" some impacts through the rear seat post.


----------



## TandemBear (Aug 18, 2013)

alien too said:


> I was looking for advice on which wheel size I should go with.
> I will be doing marathon races on it.


Now that I have a year on a 29" full suspension bike, I'd not hesitate for a second to go with a 29" tandem. My only reason for going 27.5" would be if proper fit couldn't be achieved with 29". My stoker is 5', so it made total sense for her to go with 27.5" wheels on her new single full suspension bike. But if you CAN ride 29" wheels, why not? My next mountain tandem will be a 29" for sure, probably a Ventana ECDM.
And as mentioned earlier, you don't have the luxury of lifting the whole bike up and over many obstacles, so the "rollover" advantages of the larger wheels is a huge plus. Those large wheels plus 160mm suspension travel? Unstoppable! That said, I lift the tandem front wheel off the ground all the time, so I don't get the "you can't lift the front end" comment. We bunnyhop too, but it's virtually useless as you can't clear anything with the long wheelbase.
And if doing marathon races, then this further justifies the larger wheels.
Slow steering? Sorry, I don't really see it. Tight, technical single track has been zero issue on the 29" full suspension for me so far. Tahoe Rim Trail, Nevada City's Harmony Ridge (Hoot, Scotts Flat, and now Talon Show) are all the best! It's way, way better with the larger wheels. I feel the heavier weight of the larger wheels, heavier tires and sealant, for sure. But that's a trade-off I'm more than happy to accept. (****, I took an 11 lb. weight penalty going from my ti hard tail to the Ibis. Totally worth it!) I rode Hole in the Ground at Donner Pass last October. (I've done it several times on the 26" single and 26" tandem.) But it had been a few years since I had ridden it; my fitness just wasn't there. So I head on up with much better fitness to ride it again - and on the new Ibis. How exciting! Was really looking forward to it. But at 56 yo, I took it with a cautious approach: I won't pressure myself to try to ride everything. Get off and walk to be able to ride another day type of thinking. (I enjoy mellow observed trials goofing around; I like technical challenges.) Despite riding with a partner, I'd still take it easy. Well, I quickly found the 29" wheel so sweet, I attempted everything. Cleaned it all, save for three spots where my fitness and the altitude gassed me. (My friend on his 26" bike went OTB, BTW! Glad he was basically uninjured.)

So with my experience on the 29" wheels and no size constraints (5' 9" riding size M or L), it would be a 29" tandem without much more thought.


----------



## Trifo (2 mo ago)

We switched from 26" to 29" 2 years ago and we are just happy AF. Also I changed my "half" bike from a 27,5" fully to a 29" hardtail and I am wery happy with that too. Thus I would clearly recommend 29" in any circumstances.

It is not a fully, but my beloved stoker's got a Thudbuster as bump protection.


----------



## Fun on Wheels (Nov 27, 2013)

We have a 27,5 Lapierre now for two years. Riding 26 inch when we bought it. Replaced the wheels for 27,5, love it. My wifi is very good off road, but she hates it on the tandem. Maybe a full suspension will work. Thudbuster on the wishlist now!


----------

