Mountain Bike Wheel Size Experiment | Riding With A 29er Front & 27.5 Rear

Mountain Bike Wheel Size Experiment | Riding With A 29er Front & 27.5 Rear

– So, I’ve already done a
video with my Scott Genius running the different size wheels. So this bike is designed
to run a either 29 or 27 and I put it to the test
with times but also to see just how different the bike felt. But, today it’s time
for something different, it’s something I’ve only
seen on E-bikes so far. I’m gonna try it with 29’er
up front and a 27.5 plus on the rear and put it to the test, see if it’s worth doing
and if you can do it, does it mean you should do it. (eclectic music) So, I’ve been running this
bike now for a couple of months with the 29″ wheels and it’s
been riding great to be honest. But, I’ve swapped the rear
now for the smaller wheel. It’s a 27.5 and I’ve got a 2.6 inch tire, so it’s not only wide
but it’s deep as well. People are starting to
shy away from calling them plus a little bit nowadays
but it’s definitely wider than your average tire. Up front, I’ve got that 2.4
so it’s narrower but it’s also less tall so it’s going
to feel a little bit different. Also on this bike you’ve
got that flip chip, which I’ve actually left in
the low position for now, so the bike has slackened out quite a lot. I’m going to ride it like this
first and then I’ll flip it over to high so that will equal
the bike out a little bit, almost like I’m running
29s front and rear again. But I’ll try them both, see how it feels. (soft music) So, I’ve seen people DIY
this to their E-bikes, so obviously you’ve got plus
size tires on those bikes, so you’ve got space to chuck
a bigger wheel in the front and it should work. Canyon now released their
Spectral On, E-bike, with this set up from standard. But does it make a little
bit more sense on an E-bike? Where you’ve got all
that power going through that rear wheel to have that bigger tire, you get a bit more drive on the floor. Is it going to work on all bikes? I don’t know yet. How do you think it looks? Let me know in the comments down below. At the moment, if you ask me, I think it looks a little bit weird. I’m definitely not used to
seeing a bike look like this. But, I’ll take it for a
ride and see how it works. (eclectic music) (water splashes) First impressions, it’s wet, very wet. Oh, you mean the bike. Well, it feels slack, you know
when you just sit on a bike, I can see the fork going away from me. So it does feel super slack, meanwhile all I’ve really done
is just reduce the size of the rear wheel so that is gonna drop everything as well. BB is quite low, I’m gonna do a video on JMBN tech, which will be coming out
the same day as this video. So I’ll go into the stats,
the numbers, the figures. All of that stuff in that video. This one is all about feel, really, and it does feel slack.
I think the BB is so low it might cause me some issues when it comes to pedaling
through rough stuff, with stumps and things, got
to be careful of smacking my pedals into the floor, but for now I’ve just pedaled up the climb
and down these few jumps. Feels alright, it definitely
feels a little bit different. It almost feels like I’ve
got a really soft rear tire. Just cause when I’m riding
over the little bumps I just don’t feel it quite
so much through my feet. I can feel the front or a
bit more through my wrists, but yeah I’m keen to
crack on, see how it goes. (drum and bass music) (water splashing) Well it’s so wet I feel just
like Danny Hart at Champery, and just like Danny I
do struggle a little bit with dragging my bum on the rear tire. Danny’s a bit shorter than me so I bet he does it a bit more often, and I said that about
this section of track actually when I rode it last
time with the bigger wheels. I do drag my bum a little bit when I’m trying to squash over things. Of course with a smaller rear
wheel I’m not gonna get that, so that’s one advantage
of running this setup. I do feel like it’s too slack though, so what I’m going to do is flip that chip the other way around, raise
up the BB a little bit. Make it a little bit
steeper on the head angle. I think that’s gonna balance
the bike out a little bit. I won’t risk whacking my feet on any roots or rocks or anything. (soft music) So I don’t know exactly what that’s done to the angles of the bike, but it feels much more balanced now,
bringing it back up. Doddy has lent me his
digital angle finder thing. It’s probably got a much
better name than that. But I’m going to use
that in the tech video that I’m going to do very shortly to tell you just exactly what
that has done to the bike, but sitting on the bike
I think it feels better. So, time to give it another ride. (Electronic Percussion Beat) Right, so I am scratching my
head about this little mod, to be honest. I can see the
bike’s really versatile, I talked about it in the other videos, we can run either 27.5 or 29.
What about mixing the two up? I really don’t feel as much difference as I thought I would, to be honest. The rear tire does soak up
some of those little bumps, it feels a little bit, sort
of, softer on the back. But one of the biggest
disadvantages for me, I talk about this in other videos as well, is with the wider tires,
they just float a little bit. Now today it’s wet but
it’s actually not really that muddy, the tires are digging through, but I think the back tire’s
always going to perform differently to the front,
even if you put two of the same sort of
tread compound tires on. Like a Baron on the back
and a Baron on the front, they’re still going to perform
completely differently. So for me I don’t think
it’s enough of an advantage to run the smaller rear tire. Maybe if you ride somewhere
that’s really rough, really chattery it might help to have that bigger wheel on the front,
just to reduce some of that sort of feedback through the wrists, and the deeper rear tire on the back to sort of soften those
blows a little bit. But for me, I think I’d choose just either 27.5 or 29 front and
rear, and not mix the two. If we’re talking about racing, the UCI also say that you can’t
run different size wheels. You have to pick one
size for front and rear. However, I don’t think
you’re gonna ride this bike in a UCI style event,
you’re not gonna race it in a downhill event, and it’s not gonna be a cross country bike, it’s
more suited to enduro, and EWS isn’t UCI affiliated so it’s not gonna effect you for that, if you wanted to run
different sized wheels. So I’m not sure this mod’s for me, but I definitely think
I’m gonna try it again. Possibly in summertime
when it’s a bit drier I can really put some back to back runs with the different size wheels, and actually maybe put
some times in as well, see how that effects it. If you wanna see the tech
video, that is coming soon. That’ll be much more detailed about how this does effect the bike, and if you want to see the original video where I race the 29 vs
the 27.5 on this bike, just click up there for that one. I love to hear what you think about this, so leave your comments down below. Give us a thumbs up and
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  1. Still have a carbon Trek 9.9 69er from approx 2006/7. Got it through bike charity Dreambikes, don't think too many people were interested in it because it was so odd looking. I've done thousands of offroad miles on it, but also Route 66 (which at this point, many parts of it are so rough they could be classified as offroad)! Good to see weird ideas come back around…

  2. For me, the smaller rear is a no-brainer on trails, especially for a hard tail. The size difference isn't that much, and you get more shock absorption where you need it. Ideally the bike would be designed for it, and offset the angle/bb height changes. Works the other way around with road bikes, when speed and aero position is the only issue, nothing will go faster than a UCI banned funny bike.

  3. You would think the BB would still be higher than if it was 27.5+ front and rear, which the bike is designed to do. Or is there some other flip chip to change things based on wheel size? Also don't people normally run a wider tyre up front?

  4. A guy I know runs 27.5× 2.8 on the back and 29×3 on the front of his full rigid bike. He has a custom frame made for this set up. He rides like a maniac lol.

  5. Surely it can't be true that the lowest bottom bracket is achieved with different wheel sizes. Trigonometry says it should be somewhere in between the clearance you have with 2 small wheels and 2 big wheels.

  6. Better suited to a Hardtail? Soften up the back end for traction, yet keep the 'rollover' of the 29 on the front? Bit like the old '69er' concept?

  7. Should be running a fatter tyre up front and skinny out rear, would be better with a 27.5+ up front and a 26 in the rear.

  8. I bought a 29er hard tail with a steep 71 head tube geometry, and a short 38mm fork offset. Needless to say, I had "Toe Overlap" or my toes occasionally struck the front tire. Also, I planned run a full front fender since I mostly ride gravel roads rather than trails, and felt like keeping grit off of my drive train with myself as a bonus . My solution was to install a 27.5/650b front wheel and a 3 ring 160mm crank set to replace the 170's that were present. I kept the 29 rear wheel for smoothness on terrain. Obviously not the quickest handling bike. But I prefer the big wheel in the back since I'm an older rider, and do not have full suspension or room in the seat and chain stays for a full size plus tire with a a 650b/27.5 rear wheel.

  9. If you get chance, you guys should try Chris Porter’s Mojo Riding Geometron with 650 rear 29 front and normal size tyres. Like all Geometrons very slack but balanced with proportional wheelstays etc. In a situation like that where the bike had been properly adapted for the hybrid wheel sizes, it apparently works really well. Totally agree that a 2.6 rear is not going to dig in properly. .

  10. I have a Foes Mixer Enduro and it kills any symmetrical wheeled bike, the problem with this test is that the bike isn't designed to run mixed wheels, where as Foes and Liteville have bikes specifically designed for mixed wheels, makes a worlds difference! Sure you can convert any bike but the geometry has to be designed for it, otherwise you're not getting the best from both wheels

  11. How is it possible that changing the front wheel for a bigger size without changing the suspension setting lowers the BB ? Seems a geometry impossibility. Am I missing something ?

  12. The company liteville bikes is doing it ai ce their beginning. Its called scaled sizing. Xxs frame 24 26 wheels xxl 27.5 29 wheels. Frames sizes i between have different combinations.

    But you shouldnt use a plus tire in the back. Why you dont go with 27.5 29 trailking 2.4?

  13. “Only seen on e-bikes” except Foes has been doing this on production frames for the past 2-3(?) years…

  14. As it was conducted, this was an ill advised experiment. Geometry effects should have been minimised if the effect of the 27.5+ tyre alone was the concern. The tyre diameters, for example, of a 29 x 2.0in tyre and a 27.5 x 2.75in tyre are about the same and that is the tyres, or something similar, front and rear that should have been used on the mixed wheel bike. The 29er obviously should have had 2.0in tread (or similar) front and rear. That would confer a small disadvantage to the 29er, perhaps, due to the narrower tread front and rear but that is the cost of doing a meaningful as against a meaningless experiment.

    What would likely be learned by a validly conducted experiment is that potential gains in grip and control offered by the 27.5in rear tyre are vitiated by poor design of current high air volume tyres. And just as the design of high volume – wide and tall sidewall – 27.5in tyres leave a lot to be desired there are no 29er tyres offering the benefits of both a wide tread and a sensible tyre diameter, viz. there are no low profile 29er tyres that could offer something truly interesting to riders, that are available from any source.

  15. Dislike because of the lack of an actual decision.
    Years ago we ran 26 front and 24 rear with the fattest tire size that didn't rub too much…..
    I can say that I like that set up during winter wet riding and prefer matching size tires for summer…..

  16. Im running off set size on a 2013 stumpy. but its a 26×2.4 rear to a 27.5×2.4 I call my mullet in the front,party in the back 🤘😎 the difference is noticeable on steeper trails.or on fast bumpy trails.climbs are better

  17. Conventional wisdom says to use the bigger tire up front for better cornering, and the smaller in the rear for less rolling resistance

  18. I have been doing this for years. Mainly because I am a weaker rider and a smaller tire is easy to turn up hill. I was doing 26 rear 27.5 front. One of the best tweaks I ever made. I just got an enduro and considering doing the same to it.

  19. I did a search on this topic few months ago and got nothing. Glad someone is trying it out.

  20. Used to race motocross until i got injured, nowadays im racing enduro, because of my background in motocross im used to different wheelsizes front and rear so i think its good. Im going to try this setup on my bike this summer, think i Will like it

  21. This is not new guys god!!!!! we all forget the Penny Farting and that was a hard tail, Tiss its all been done before yawn, hahaha

  22. I've only just got into this for the last couple days now and I gotta say you guys have great information for people trying to enter this sort of thing. Just waiting for money to be right and I'll be getting started in no time thanks to you guys, thanks for all the help answering countless questions I've had as I have no idea what I'm doing haha

  23. This question isn't really related to the video but I was wondering if I could run a 2.3 tyre on 40mm rim? Is the tyre too small? Also, I have a 27.5+ bike, can I put regular sized rims on it?

  24. ok, that was a cool video but i think it's only relevant for anyone riding a scott genius. How about something most mountain bikers can relate to, like take a older 26" bike that's collecting dust in the shed… oh like an 09 Jekyll and converting it to 27.5 front and 26 rear.

  25. Sorry I'm a bit confused here. How come your BB height is lower on the 27.5/29 (on either flip chip) than it is on the full 27.5/27.5? Shouldn't it be a little higher, assuming the same flip chip position? Also, how did this feel in the dry?

  26. My bike mech of trust is an MTB rider by heart for close to 30 years and mainly rides DH nowadays. I was quite astonished to find a 26“ in the back and a 27.5“ in the rear on his „fun-rig“. He also runs tubes filled with tubeless sealant.

  27. Think someone said this already but you Need to do this again with the same width front and rear tire. Interested to hear what it feels like if you try to maneuver the bike in the air as I have heard rampage riders mixing 26 and 27.5

  28. Interesting video. How about a 27.5 back and a boost 27.5+ in the front? How would that feel/work on a bike? (full suspension).

  29. The two different width tires is a nice idea, a thinner tire in the front means your turn radius will be tighter. This is a really good idea for fat bikes because fat-bikes always have problems handling around flat corners from my experience.

  30. 27.5 in the back with a 29 in front means plowing through terrain. The 29 in the back and 27.5 in front means better handling and speed.

  31. Please do this again with all the sizes for a more comparable test!!! May I suggest using the same width tire front and rear for the mix wheel version

  32. In run 29/27,5 testet it again again … pro downhill faster more control ; contra Uphill not do good , slow in tight sections … thing about that : motocross is vor a reason 21 front 19 back !!!!

    Grüße aus Deutschland

  33. You guys are the best, thank you for all of your great videos! I have been wanting to try this setup and would love to see how it goes when it’s dry. I have a Genius (running 27.5) and I live in Orange County CA where it’s always dry. Cheers!

  34. This test was not performed properly!! You need to get a bike designed around a mixed wheel platform, not just a bike you threw a 27.5 rear on! The first one, and one I rode is a Foes Mixer, now the designer of that bike for Brent Foes has designed his own bike around it. Check out and get with a proper mixed wheel bike for your tests!!!!

  35. Was thinking of doing this with my Radon Swoop Just wondering what effect it would have? How about a test on different bike platforms?

  36. I tried this on my Banshee Prime, e13 trsR 29er up front, DTswiss EX511 27.5 out back. The bottom bracket is WAY to low for the trails we have around here. I could see doing bike park runs or flow trails, but our northeast boulder gardens and root beds are absolutely savage on cranks and pedals. I’ll stick with the rollover and BB height of the 29’s.

  37. Accidentally discovered something crazy. Damaged the frame on my road bike. Randomly decided to try riding hard tail MTB with + tires. Soooo slow. Felt like a tank. Had to keep tires at max air pressure to kill the sluggishness.

    Got a puncture in my rear wheel. Decided to change tire while replacing tube. Ran 2.3 plus tire in front and 2.1 skinny road tire in the back.

    HOLY COW! Immediately noticed the difference. Massive acceleration from skinny back tire while plus tire in front provided waaaaay better handling than my road bike ever did.

    So I started investigating and discovered this was something done by BMX racers. Gave them good acceleration and traction on dirt tracks.

  38. Liked because it's a great subject and ahead of its time. BUT… we didn't learn anything. Half the video was about the variable geometry of the frame, and 2.6 is barely plus. We need this test done with a 2.8 and 2.4 on a hardtail.

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