Confused as hell on modern geometry fit

[Duffman]

So I'm looking to replace my 10+ yo light trail FS bike , and am utterly baffled by the correct fit for a modern steep ST , slack head angle bike. This is for a do it all bike, mostly tighter mid Atlantic undulating trails, rather than long up followed by long downs. Like to go fast when I can but old now and not rad at all on a bike can't afford to break upper extremities due to work ,so allergic to big air.

Specifically I was looking at the Ripley AF, but nobody locally has any in stock to check out. Looking at Ripleys sizing, at almost 6'1 (185cm ) I'm exactly between a L an XL. Consensus on forums FWIW tends to get the bike runs small so go XL, but one local shop things trying to fit a L is better due to the local trails needing more low speed maneuverability. Confusing things even more, looking at stuff like RAD distance calculators , unless I'm doing it wrong, it looks like that considers a L frame even on the long side with it's 475 reach .

I get that RAD distance and reach / stack involve standing measurements, but what about prolonged seated pedaling which is what we do a lot around here? Im guessing with the steep seat tube angle, the ETT length here is fairly short even with a long reach. How the hell do I know if the L is big enough with this type of geometry for this type of riding?

[geomorph]

Effective top tube is generally a good start to compare to other bikes you have ridden and will dictate how the bike feels in a seated position. As someone who is usually on the M/L size split, I would also say to not overthink it. Unless you are some sort of super picky rider with fit, you can adapt either way within a few rides.

[El Chupacabra]

Play with the comparisons here - you can input your existing bike(s) and see what the difference may be like:
https://geometrygeeks.bike/

This might not be so useful if it's all foreign lingo to you.

[XtrPickels]

Ride as many modern bikes as you can, even if it's not the exact model you are looking at.
This will give you the best sense of where you are at. You can then apply that knowledge to the the bike you want.

There is a balance between proper pedaling position and proper handling position.

Proper pedaling is for the most part unchanged, especially in undulating terrain. If you tend to ride up long steep climbs to long descent, then the steep STA craze makes sense.

Proper handling is all over the map.

Steeper terrain, in my opinion, necessitates a shorter reach (and higher bars) than flatter terrain. This is because your arms are only so long and they run out of reach when the trail pitches down away from you. RAD and the similar methodologies were born from jumping and steep terrain, so their recommendations makes sense.

Longer reach / lower bars can work well on terrain that goes up and down. It's more comfortable for climbing, and in my experience can help weight the front end on flatter turns.

While many people do it, I don't think you should compromise the cockpit to achieve the handling that you want.
Example: buying a slack bike too short to improve it's low speed cornering.
Buy a bike that both fits and has the geometry to accomplish what you want.

[Peruvian]

I’m 6’1” with long arms and a 32” inseam. I ride a ‘17 Ripley LS so was in the size break as well. I bought a XL and while it seems large when i’m standing next to it, once on board I like how it rides. I probably would have been happy with a L as well and agree with geomorph that you will get used to it either way.

Maybe just ask if you want to ride on or in the bike frame for the trails you expect to pedal.

[Duffman]

Ride as many modern bikes as you can, even if it's not the exact model you are looking at.
This will give you the best sense of where you are at. You can then apply that knowledge to the the bike you want.

There is a balance between proper pedaling position and proper handling position.

Proper pedaling is for the most part unchanged, especially in undulating terrain. If you tend to ride up long steep climbs to long descent, then the steep STA craze makes sense.

Proper handling is all over the map.

Steeper terrain, in my opinion, necessitates a shorter reach (and higher bars) than flatter terrain. This is because your arms are only so long and they run out of reach when the trail pitches down away from you. RAD and the similar methodologies were born from jumping and steep terrain, so their recommendations makes sense.

Longer reach / lower bars can work well on terrain that goes up and down. It's more comfortable for climbing, and in my experience can help weight the front end on flatter turns.

While many people do it, I don't think you should compromise the cockpit to achieve the handling that you want.
Example: buying a slack bike too short to improve it's low speed cornering.
Buy a bike that both fits and has the geometry to accomplish what you want.

Makes sense, I haven't ridden a modern geometry steep seat angle short travel bike, so I wonder if that seated position makes sense for typical mid Atlantic undulating rooty / rocky trails where there isn't as much sustained climbing followed by long descending.

[Duffman]

Play with the comparisons here - you can input your existing bike(s) and see what the difference may be like:
https://geometrygeeks.bike/

This might not be so useful if it's all foreign lingo to you.

The numbers make sense , just in 2007 Cannondale didn't publish ETT / Stack / Reach so I'll have to measure. Very different numbers though w a 26" with 74 deg seat and 69 deg head angle , although it was low and long for the era

[detrusor]

I’m with Peruvian. 6’1” 180, long arms and a 33” inseam. Chose an XL in a ripley V4….the large was way to short in the cockpit


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[J. Barron DeJong]

I made the switch from a 2003 era bike to a modern trail bike (Norco Optic) last year. No question from my experience that the XL would be right for you.

The Ripmo XL is a little smaller than the Optic XL, and based on Norco’s sizing rec’s, your 6’1” would put you smack dab in the middle of the range for that Ripmo XL.

At 6’4”, I’m right at the top of the recommended range for my XL Optic, and ideally I’d like the frame to be a little bigger than it is, maybe 520mm reach instead of 510.

Also note that while the 76 degree seat tube angle is steeper than the old bikes, true winch-and-plummet bikes these days are more like 78 degree seat angles.

Edit: I also think the broadness of the recommended size range that Ibis shows is optimistic. Someone 5’7” shouldn’t be considering the same frame size as someone who’s 6’1”, or at least if they are, those people are both outliers in terms of how someone generally wants their bike to fit.

[toast2266]

X2 on paying attention to the effective top tube length. You spend a lot of time seated and pedaling, and if your ETT is too long or too short, you'll be uncomfortable. What was a comfortable ETT on a bike 10+ years ago isn't any different now. Yes, a steeper seat tube will mean your seated body position is different relative to the BB, but don't worry too much about that; for most people, that's easy to adjust to (or sometimes not even all that noticeable).

Also agreed with your conclusion that you're kinda between sizes on the Ripley AF. If you're dead set on that bike, I'd probably lean towards sizing up, but a better option might be to hunt around for a bike that's more appropriately sized for you.

[XXX-er]

both Yeti & SC's recs were spot on for me and i like the new designs way > than those from 15 yr ago but not everybody digs them, I think you wana check out how some of the modern bikes feel cuz not every body likes the new cockpit setup which are more upright IME

[VTskibum]

^^ I generally agree with toast, but being local to your area I think size Large Ripley would be best. Guessing based on location you're locals are Wiss, Belmont or similar? I'm N/W of Philly and there are a few trail systems where going longer would benefit; especially Mt Penn and maybe Birdsboro, otherwise our descents are still more twisty than high speed.

Guessing even a sized down relatively modern Downcountry/Trail bike is going to feel longer than your 26" bike. Modern geo bikes are soo much more capable than the old stuff!!

[Falcon3]

Ibis rec had me firmly in a Large Ripmo AF. I bought a medium based mostly off how my previous bike feels and its reach/stack. I also tinkered with Lee’s RAD formula and measurements and think there’s something to it. My medium is RAD+.

The medium fits perfect even with my short legs and long arms. Super stable on the down but way easier to maneuver on technical ups than a large would have been. I’m now in the camp that believes size recommendations have gotten too big.

[Eluder]

Ride as many modern bikes as you can, even if it's not the exact model you are looking at.
This will give you the best sense of where you are at. You can then apply that knowledge to the the bike you want.

There is a balance between proper pedaling position and proper handling position.

Proper pedaling is for the most part unchanged, especially in undulating terrain. If you tend to ride up long steep climbs to long descent, then the steep STA craze makes sense.

Proper handling is all over the map.

Steeper terrain, in my opinion, necessitates a shorter reach (and higher bars) than flatter terrain. This is because your arms are only so long and they run out of reach when the trail pitches down away from you. RAD and the similar methodologies were born from jumping and steep terrain, so their recommendations makes sense.

Longer reach / lower bars can work well on terrain that goes up and down. It's more comfortable for climbing, and in my experience can help weight the front end on flatter turns.

While many people do it, I don't think you should compromise the cockpit to achieve the handling that you want.
Example: buying a slack bike too short to improve it's low speed cornering.
Buy a bike that both fits and has the geometry to accomplish what you want.

So you're saying it depends?

[Duffman]

^^ I generally agree with toast, but being local to your area I think size Large Ripley would be best. Guessing based on location you're locals are Wiss, Belmont or similar? I'm N/W of Philly and there are a few trail systems where going longer would benefit; especially Mt Penn and maybe Birdsboro, otherwise our descents are still more twisty than high speed.

Guessing even a sized down relatively modern Downcountry/Trail bike is going to feel longer than your 26" bike. Modern geo bikes are soo much more capable than the old stuff!!

Yep, dead nuts accurate on the usual riding haunts, with forays up into upstate NY and down to white clay , middle run ,etc. Based on this I also thought the L wheelbase would be better if I could pull it off, but don't want to be in a cramped seating position and uncomfortable.

[jacob_dbu]

I definitely did not like the super steep seat tube angles, but I do like the longer reach for steep trails. I think I could have gotten used to it, but I settled on a bike with a slightly more traditional seattube angle (e.g. 75.5-76 vs 77/78 of some of the ultra-modern bikes).

I sized up and went for a large when I was between M and L and I'm still not 100% sure that was the right choice, but I am getting more used to it. Partially because the large is what I could find at a price I wanted.

[supermodel159]

Get the XL.

[XXX-er]

Ibis rec had me firmly in a Large Ripmo AF. I bought a medium based mostly off how my previous bike feels and its reach/stack. I also tinkered with Lee’s RAD formula and measurements and think there’s something to it. My medium is RAD+.

The medium fits perfect even with my short legs and long arms. Super stable on the down but way easier to maneuver on technical ups than a large would have been. I’m now in the camp that believes size recommendations have gotten too big.

how tall are you ?

both SC and Yeti put me on a medium at 5'8" and that has been perfect, i think they both fit the same at least in medium

I initialy took out a large Yeti 5.5 cuz I could ride an already dirty large shop bike but it felt long and it was 1 " longer TT than medium, bought the medium and it was perfect

[Eluder]

There are lots of numbers that come together to make any given bike what is, some of which isn't visible in the published geo chart. We all have our personal bias but I think in general if you are a large you are large in how that company has decided to build their bikes. Sizing down or up can push a bike out of how it was conceived when in actuality you would probably be better served on a bike designed around different parameters. For sure this doesn't help if you truly are between sizes but it sure seems most people that are "between" sizes should be on the bigger bike but are hesitant.

I am sure I am opening a can of worms here but If you really think you know better than the bikes designer than why are you buying bike from them?

[J. Barron DeJong]

How come Ibis can’t convert between cm and inches properly?

173 cm is not 5’7”. 198 cm is not 6’5”.

Get the XL. Put a 50mm stem on it and go ride.

[toast2266]

I am sure I am opening a can of worms here but If you really think you know better than the bikes designer than why are you buying bike from them?

I am 100% confident that bike designers can't give a single recommendation that works for every person in every location.

Case in point: Jack Moir races on a size small Canyon Spectral. He's 6'1" and can get whatever size bike he wants. His decision appears to be working for him, despite Canyon's sizing recommendations.

edit: don't you have both a medium and a large in the exact same bike from the company you work for?

[EWG]

X2 on paying attention to the effective top tube length. You spend a lot of time seated and pedaling, and if your ETT is too long or too short, you'll be uncomfortable. What was a comfortable ETT on a bike 10+ years ago isn't any different now. Yes, a steeper seat tube will mean your seated body position is different relative to the BB, but don't worry too much about that; for most people, that's easy to adjust to (or sometimes not even all that noticeable).

Also agreed with your conclusion that you're kinda between sizes on the Ripley AF. If you're dead set on that bike, I'd probably lean towards sizing up, but a better option might be to hunt around for a bike that's more appropriately sized for you.

Toast is giving you good advice here.

Picking a bike that fits is independent of geometry and style (kinda of - read on.)

Fit starts with your seat relative to your pedals. Based on leg length, femur length etc. When on your seat your knees need to be in the correct position relative to your pedal spindles. Old method (and still a good home check) is to drop a plumbbob straight down from the little budge directly under your kneecap when the knee is bent and the pedal is in the forward 90 degree position. Plumb string should run very close to directly through the pedal axle in that position. Some folks like it to go even with the end of the crank. That's more of a spinning position. Through the spindle is a little more for power, slower pedaling (like in mtb), and you can go even further back but only for specific reasons and I would not recommend it.

After that, you figure out reach. Think of it as an arc - really low bars need to be closer to you than really high bars to exist on the same reach arc, and bar width impacts it as well. That arc really is a circle around your hip bones in a perfect world (though it gets screwed up when you go real low or real high - you aren't likely to do either.) At this point you can start thinking about bike type. Figure out your riding style, trails, and bike type. That will help figure out your bar width, height, etc. If your current bike feels super comfy, then use the distance from your hips to your bars as the goal to hit on your new bike. This is a 3D measurement - it includes the distance sideways to your grips.

Now you pick your suspension type/bike design. See what the different manufacturers are that make that style, and then see what the differences are in effective top tube length between those manufacturers. Pick the one that is most likely to get your reach right.

Most people do it backwards. Buy the bike (usually based on cool factor and/or color...sort've not joking), set the handlebar height and width, then adjust the saddle location till the reach is comfortable. That's super messed up, and only works on DH bikes where there is very little seated pedaling. If the amount of power you can generate matters to you, always, always, always set your saddle location first, then find a bike that works with your reach.

Make sense?

[Duffman]

There are lots of numbers that come together to make any given bike what is, some of which isn't visible in the published geo chart. We all have our personal bias but I think in general if you are a large you are large in how that company has decided to build their bikes. Sizing down or up can push a bike out of how it was conceived when in actuality you would probably be better served on a bike designed around different parameters. For sure this doesn't help if you truly are between sizes but it sure seems most people that are "between" sizes should be on the bigger bike but are hesitant.

I am sure I am opening a can of worms here but If you really think you know better than the bikes designer than why are you buying bike from them?

I don't disagree, but in this case 6'1 is the very top limit of the L and the very bottom limit of the XL on the Ibis chart. Truly between sizes.

Interestingly enough, based on some tips earlier in this thread , I started looking at similar short travel 29 trail bikes and was surprised how close the numbers are now. For example the Giant Trance 29 vs the Ripley AF , both in large. But the Giant size guide has the Large going up to 6'2 and I haven't heard as much chatter online about it fitting small .


Ibis Ripley AF
2021: Large

Giant Trance 29
2022: L

Reach 475 480
Stack 622 622
Top Tube (effective) 630 624
Seat Tube C-T 418 465
Head Angle 65.5 66.2
Seat Angle 76 77.0
Head Tube 115 120
Chainstay 432 437
Wheelbase 1217 1223
Standover 722 759
BB Drop 35
BB Height 335
BB Type BSA
Fork Rake / Offset 44 44
Trail 114 120

Looking at this at least to my confused eyes, they should fit quite similar with the Giant potentially having even a little less cockpit room, right?

[J. Barron DeJong]

When on your seat your knees need to be in the correct position relative to your pedal spindles. Old method (and still a good home check) is to drop a plumbbob straight down from the little budge directly under your kneecap when the knee is bent and the pedal is in the forward 90 degree position. Plumb string should run very close to directly through the pedal axle in that position.

I disagree with this. KOPS worked ok for old school road bike geometry, but even in road bikes the trend has been to a more forward saddle position as riders have tried to get into lower more aero positions. The new(er) short nose saddles are a part of this since there’s a rule about how far the nose of the saddle needs to be behind the BB.

With modern geometry MTB’s most people would need to slam the seat back on the rails to get their knee over pedal spindle, right? I mean, if it falls into place properly on a road bike with a 73 degree seat angle, you’re going to be forward of that position with a 76 (or 78) seat angle.

[toast2266]

Looking at this at least to my confused eyes, they should fit quite similar with the Giant potentially having even a little less cockpit room, right?

Yeah, just in terms of sizing, those two bikes look quite similar. I would say that none of the differences are large enough to really matter. Especially because there's a little bit of bullshitty-ness with any stated geometry numbers, so take them all with a little bit of a grain of salt.