wheel size and rider size/comfort.

[Jackson-Lewis]

Hey all, so while I still decide on a bike i've been learning about wheel size differences (i am still split on it) but for a bike the same size do the 29" wheels actually make the full 1.5" difference in seat height?

I am 5'5" and was on a med frame (rocky mountain) with 27.5" wheels before..... but I was not fully flat footed on the ground when stopped with seat down (heel was up just a little) so I am thinking if the wheel makes that much of a height difference I may be better to stick with 27.5" and a med..... but open to 29" pn a small frame........
my main thing is I will use the bike I get for a ton of climbing in everyday use too.......


any thoughts are helpful.

 

[steve_sordy]

Most bikes tend to come with the bottom bracket at approximately the same height above ground. This may increase if the travel is big, but mostly the balance between ground clearance, travel and crank length has been fully researched. So how do they deal with a wheel that is 3" larger diameter than the old 26ers we grew up on? The answer is the frame design. You will find that bottom bracket height is below the centre-line of the wheel axles. On geometry diagrams the BB height is often quoted as a negative (ie -23, meaning 23mm below). On my bike they call it BB drop and on all sizes it is 20mm. The seat tube reduces too, and therefore the saddle height comes down with it. The bike may also come with a reduced travel dropper so that when the dropper is fully inserted into the seat tube, the fully extended dropper does not place the saddle too high for the inside leg of the customer that size of bike is designed for.

So in theory, anybody can ride a 29er? Err not always. Designers struggle to find a frame design for small statured riders that is not too long or tall, yet still has room to fit two big wheels in there. The front wheel has to have sufficient room to turn without the rider's feet getting in the way.

It is for you to decide whether the frame compromises are ones you can accept for the perceived benefits of a 29er, vs the next wheel size down. You need to test ride a 29er if you can, if you can't I would go safe and opt for a 27.5 wheeled bike.

When you think about it, there is something entirely natural about wheel height being linked to person height. Yes there is a big overlap, but as children grow they progress through 10", 12", 16", 20", 24", 26" wheels. Then it used to stop. I always had a feeling at the back of my mind that at 6'1" there ought to be a bigger wheeled bike for me than 26". There was, but it wasn't on an mtb. I assumed that it was because the wheels weren't strong enough, how wrong I was! There was a guy on here recently and he was a giant and even XL 29ers were too small for him, he could have done with a 32" wheeled bike (probably). Initially I was unconvinced by the 29er proposition but I was quite happy to go 27.5 when the opportunity arose. The early 29er geometry issues have all been resolved and, eventually, I opted for a 29er as my current bike. After trying 27.5" then 29", I'm still undecided, as I have had the most enormous fun on both wheel sizes. But I would not choose to go back to 26".

 

[Jackson-Lewis]

Most bikes tend to come with the bottom bracket at approximately the same height above ground. This may increase if the travel is big, but mostly the balance between ground clearance, travel and crank length has been fully researched. So how do they deal with a wheel that is 3" larger diameter than the old 26ers we grew up on? The answer is the frame design. You will find that bottom bracket height is below the centre-line of the wheel axles. On geometry diagrams the BB height is often quoted as a negative (ie -23, meaning 23mm below). On my bike they call it BB drop and on all sizes it is 20mm. The seat tube reduces too, and therefore the saddle height comes down with it. The bike may also come with a reduced travel dropper so that when the dropper is fully inserted into the seat tube, the fully extended dropper does not place the saddle too high for the inside leg of the customer that size of bike is designed for.

So in theory, anybody can ride a 29er? Err not always. Designers struggle to find a frame design for small statured riders that is not too long or tall, yet still has room to fit two big wheels in there. The front wheel has to have sufficient room to turn without the rider's feet getting in the way.

It is for you to decide whether the frame compromises are ones you can accept for the perceived benefits of a 29er, vs the next wheel size down. You need to test ride a 29er if you can, if you can't I would go safe and opt for a 27.5 wheeled bike.

When you think about it, there is something entirely natural about wheel height being linked to person height. Yes there is a big overlap, but as children grow they progress through 10", 12", 16", 20", 24", 26" wheels. Then it used to stop. I always had a feeling at the back of my mind that at 6'1" there ought to be a bigger wheeled bike for me than 26". There was, but it wasn't on an mtb. I assumed that it was because the wheels weren't strong enough, how wrong I was! There was a guy on here recently and he was a giant and even XL 29ers were too small for him, he could have done with a 32" wheeled bike (probably). Initially I was unconvinced by the 29er proposition but I was quite happy to go 27.5 when the opportunity arose. The early 29er geometry issues have all been resolved and, eventually, I opted for a 29er as my current bike. After trying 27.5" then 29", I'm still undecided, as I have had the most enormous fun on both wheel sizes. But I would not choose to go back to 26".

Ok that makes sense.... guess my main issue is will I be able to find the one(s) i need to ride before I buy....... as the main difference stated by most and the company seems to be wheel size even standover height is less than a full inch difference it seems....... and I am still new to really knowing what all this means.

 

[IanVersion2]

I'm not sure why you want to be flat-footed with the seat (dropped) down? I would normally think as long as you have a bit of clearance between yourself and the top-tube when standing flat-foot, astride the bike, that's the more important thing. For just stopping while seated normally just being able to comfortably get one foot down is enough.

 

[Philly G]

Just to add to @steve_sordy 's reply. Wheel size has nothing to do with bike fit, that is down to frame size and geometry. A 29er in a medium will fit you just as well as a 27.5 in a medium, assuming that the bike is sized correctly for you in the first place. Say you have two bikes, 27.5 and 29, with the same bottom bracket height, say 333mm. On the 29er, the bottom bracket will be lower in relation to the axle height, due to the bigger wheels. This gives the rider the feeling of being more "inside" the bike rather than perched on top, which feels more stable and confidence inspiring. This is particularly helpful for taller riders. The bigger wheels roll better over roots etc, but the downside is slightly less agility than the 27.5, so can be more of a handful on tight switchbacks. Mullet bikes are designed to give the best of both worlds, 29er up front to monster truck over obstacles, and the 27.5 out back for snappier handling. It comes down to personal preference. Excellent rollover and stabilty of the 29er, or the agility and playfulness of the 27.5. I started out with 27.5, but my new bike is a 29er, and being a taller rider, I prefer it, but at times I do notice it's not as easy to get around tight corners.

 

[Jackson-Lewis]

ok yeah go to see two of the bikes I was looking at next to each other one on 27.5 the other on 29" not a big enough stand over to make a difference (Less than half inch stand over difference)..... sadly both were to large to even try out safely with my injury.... but gave me a good idea, guess I may just need to decide and go with one if I am stuck ordering.....

 

[Philly G]

ok yeah go to see two of the bikes I was looking at next to each other one on 27.5 the other on 29" not a big enough stand over to make a difference (Less than half inch stand over difference)..... sadly both were to large to even try out safely with my injury.... but gave me a good idea, guess I may just need to decide and go with one if I am stuck ordering.....

27.5 versus 29er is a long-time debate, pros and cons of each, there are heaps of excellent videos about this on youtube, maybe watching some of these would help you decide

 

[Jackson-Lewis]

27.5 versus 29er is a long-time debate, pros and cons of each, there are heaps of excellent videos about this on youtube, maybe watching some of these would help you decide

yeah been watching all week...... I really cannot decide...... I'm doing urban commute (big climb both ways) as well as coulee riding with treck up and down mountains (nothing black diamond or ultra hardcore like racing)

 

[Philly G]

Well, given that you already know what it's like to ride a 27.5, seems like the only way you'll be able to decide is to try a 29er, if that's at all possible

 

[Jackson-Lewis]

Well, given that you already know what it's like to ride a 27.5, seems like the only way you'll be able to decide is to try a 29er, if that's at all possible

yeah, I'm stuck because no one has one in a med frame in town :/