Confused as hell on modern geometry fit

[J. Barron DeJong]

This is a fair point. That said, we are venturing into mtbr territory here.

Most studies over the last handful of years have equated a more forward saddle position with increased efficiency, which furthers your point. Here's a good one: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5786204/
Though some of that is trying to get aero, which doesn't apply here.

Remember that saddle position is somewhat independent of seat angle - to a point. You can slide the seat forward and back as needed. But seat angles increased on mtn bikes for reasons not necessarily related to leg position - mostly as a response to wheelbase getting longer and still having rider reach work. One other note - early mtn bikes had super shallow seatposts. Getting steeper was very necessary. But published steepness doesn't equal real world steepness, as your rear shock sag will make your seattube shallower - up to 3 degrees for a long travel. So your "supersteep" 78 degree seattube is actually working like a 75. Going uphill also creates an effectively shallower seattube.

Long story short - I buy what you are saying to a point. Having your knee a bit ahead of your spindle makes sense. But I don't think it will be wildly forward.

Regardless, your decision on this doesn't change the basic advice: Whichever saddle position you choose relative to your feet, set it first, then size your bike so the cockpit fits - not the other way around.

How does the fact that I now slam my cleats as far back as possible play into all this?

ETA: I would say your desired final form is going to play a part in where the saddle position ends up. For example, a time trial position is going to end up with a more forward saddle position than a road race bike because of the position your upper body is trying to achieve.

So I don’t think it’s as simple as setting the desired saddle position first. Or at least, if you set the saddle position first, you’re going to go about fitting the rest of the bike around that position, which may not end up with an optimized fit/performance. (This is probably especially true if the bike you’re coming from a bike that has very dated geometry.)

[EWG]

How does the fact that I now slam my cleats as far back as possible play into all this?

I'm almost certain that means you're drunk. I mean, you're drunk, right?

Slamming your cleats back allows your knee to stay behind your toe. There's a whole damn set of conflicting theories on the most powerful cleat position. Personally I kinda hate it moved back, but I'm pretty used to cleats under the ball of my foot.

Here's an argument for moving it back:

https://neillsbikefit.com.au/?page_id=348

Personally, I think he's totally discounting any foot articulation. I can't imagine sprinting like that. Based on his logic, the cleat should be under the heel. Which makes little sense. But the argument goes that while the calf being involved can give you power, it doesn't help with endurance. Say what?

But I'm keeping an open mind.

[skizix]

Almost certainly get the XL. But it somewhat depends mostly on two things:

- are you super torso-y or super leggy? If most of your height is in the legs, lean towards the L

- what do you normally ride? If it’s super twisty xc stuff at moderate speeds, the L will me more flickable. If you most enjoy slaying the DH, bias toward the XL.

But mostly:just get the XL

[J. Barron DeJong]

I'm almost certain that means you're drunk. I mean, you're drunk, right?

Well, I did crack open a beer right before posting that, but I think it would be a stretch to say I’m drunk….

is it better or worse if this is just how I am normally?

[EWG]

Well, I did crack open a beer right before posting that, but I think it would be a stretch to say I’m drunk….

is it better or worse if this is just how I am normally?

Waaay better. Me too. Cheers.

I just called a pro road/cyclocross/xc cycling coach I know well. He has world class racers he trains. His comment was that if moving your cleats back and saddle forward was fastest way to go all the pros would be doing it. He said none of them are. Also, FWIW I just checked my Tracer 27.5. Granted, it's 75 degree seat tube is not super steep, but when I sit on it, after sag, my kneecap is right over the pedal spindle. So it still kinda works, at least for me.

Also, he had another good point. He said that in his world, the triangle doesn't change - in other words, your three contact points - seat, feet, hands - make a triangle. There is a proper triangle for your each discipline. If you move the seat forward, the hands should go down - which is why tri bikes, in pursuit of aero, move their seats forward.

Anyway, this is a good discussion. Thanks for starting it.

Ok, now its time for me to catch up to you on the beer front.

[toast2266]

I'm almost certain that means you're drunk. I mean, you're drunk, right?

Slamming your cleats back allows your knee to stay behind your toe. There's a whole damn set of conflicting theories on the most powerful cleat position. Personally I kinda hate it moved back, but I'm pretty used to cleats under the ball of my foot.

Here's an argument for moving it back:

https://neillsbikefit.com.au/?page_id=348

Personally, I think he's totally discounting any foot articulation. I can't imagine sprinting like that. Based on his logic, the cleat should be under the heel. Which makes little sense. But the argument goes that while the calf being involved can give you power, it doesn't help with endurance. Say what?

But I'm keeping an open mind.

I'm not drunk, but I'm definitely buzzed. Cheers!

Slamming your cleats back means you can do a 4,000' descent without completely torching your calves.

If every other aspect of my bike's geometry is geared towards making descents awesome, there's no point in ruining it with my cleat placement just so I have marginally more efficient foot articulation.

[whyturn]

So lee likes bikes has a rider area dimensions or RAD. Seems to work really well. You tube video to see


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[EWG]

I'm not drunk, but I'm definitely buzzed. Cheers!

Slamming your cleats back means you can do a 4,000' descent without completely torching your calves.

If every other aspect of my bike's geometry is geared towards making descents awesome, there's no point in ruining it with my cleat placement just so I have marginally more efficient foot articulation.

100%. Gotta know what your shooting for.

Opening a beer right the fuck now. FKNA Cheers.

[VTskibum]

I'm not drunk, but I'm definitely buzzed. Cheers!

Slamming your cleats back means you can do a 4,000' descent without completely torching your calves.

If every other aspect of my bike's geometry is geared towards making descents awesome, there's no point in ruining it with my cleat placement just so I have marginally more efficient foot articulation.

I ran them further back when racing XC after suffering some pretty bad calf cramps one season. Ridden that way since, also left them for CX and gravel riding as a result. My road shoes tend to be bit more traditional though.


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[Duffman]

So lee likes bikes has a rider area dimensions or RAD. Seems to work really well. You tube video to see


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RAD was one of those things that confused the hell out of me and had me start this thread. I measured my RAD at 83cm ish. But here we are debating a L vs XL Ripley AF, while Lee has an 83 RAD fitting to a Medium, which seems completely bonkers.

Almost certainly get the XL. But it somewhat depends mostly on two things:

- are you super torso-y or super leggy? If most of your height is in the legs, lean towards the L

- what do you normally ride? If it’s super twisty xc stuff at moderate speeds, the L will me more flickable. If you most enjoy slaying the DH, bias toward the XL.

But mostly:just get the XL

Pretty average torso vs legs, 33.5 inseam so maybe slightly more leg. Ride mostly tighter twisty , rooty and rocky EC singletrack vs bombing DH or flow trails. But it does seem the consensus is go bigger .

[toast2266]

Pretty average torso vs legs, 33.5 inseam so maybe slightly more leg. Ride mostly tighter twisty , rooty and rocky EC singletrack vs bombing DH or flow trails. But it does seem the consensus is go bigger .

At the end of the day, I think you're over thinking this. Realistically, you'll be happy on either a L or XL, but you'll be happy in different situations. Faster, rougher trails, you'll be happier on the XL - it'll be more stable, and you'll have more room to move around without upsetting the bike's balance. In slow chunk you'll be happier on the large. More maneuverable and easier to man handle the bike. You'll be able to make either work OK on climbs with some tweaks to stem length and saddle position.

There isn't a wrong answer here. Pick a size and be a dick about it.

[HAB]

RAD provides exactly zero information that reach and stack don't. And I think it's a pretty dumb way to size bikes, because you have a fair bit of ability to adjust bar height via spacers and bar rise and so on.

[Duffman]

At the end of the day, I think you're over thinking this. Realistically, you'll be happy on either a L or XL, but you'll be happy in different situations. Faster, rougher trails, you'll be happier on the XL - it'll be more stable, and you'll have more room to move around without upsetting the bike's balance. In slow chunk you'll be happier on the large. More maneuverable and easier to man handle the bike. You'll be able to make either work OK on climbs with some tweaks to stem length and saddle position.

There isn't a wrong answer here. Pick a size and be a dick about it.

Ultimately this is the correct answer. Thanks again for the info earlier though!

[TrueNorth]

I was just in a similar situation, but debating between the M and L Ripmo AF (and also Ripmo vs. Ripley, but that's a subject for another thread). I have longish arms for my size, which puts my RAD measurement low and squarely in size S, which seemed ridiculous. I asked for advice in another thread, and opinions were pretty evenly split between M and L.

In the end I concluded:
-RAD seems to be mostly based on controlling the bike in the air (i.e. on jumps), which I don't intend to do much, so I decided to disregard it.
-I could probably adjust to either size after riding it for a while
-there's no easy way to try them locally, so I need to pick one and get on with it
-the size L Ripmo AF was in stock, so that's what I have coming to me.

If it's really the wrong choice (which I doubt), either a) I won't know better because I have only my old school mtb to compare to, or b) I will sell it next year and get something else.

[whyturn]

RAD. I think there is something to it for sure. My rad is weird cause I have 34 inseam but really long arms so RAD is 34. I thought long arms meant bigger bike. Not true for me
I took like 3-4 tries and measured 34 on my rad. My old cannondale is 34 and new revel rail looks to be 33. Cannondale was an xl. Revel is large So rad minus. It feels like a good size for me. Short 35 mm stem so I go to 50mm and I can roll bars if I need to make it slightly bigger. Based on my garage measurements I have the right size bike.

Maybe call the shop and ask them to measure the rad on the bikes. Takes like 2 minutes to measure. Then compare at home to your measured rad

Anyways hope you get the right bike. I bought an XL Santa Cruz and way to big. It’s not just height at all IMO


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