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Frame size and "fit"


Lacch

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I asked a seller why they had a bike listed as M/L when the sizes available for this model are strictly M or L (no middle option)

this was the answer I got:

"It’s a medium with 29 tires, so it can fit people who usually ride a large"

The question is... do different size tires really have an effect on "fit"? seems like frame "fit" should be constant regardless of tire size, but I have no idea...

Edited by Lacch
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18 minutes ago, TheX said:

IMHO, no. Fit is so much more.

Agreed.  Fit is fit.  You can find kids bike with 29" tires and they technically designed the bike to 'fit' a 5' tall kid.  What you find is that there are a lot of compromises made to shove a bigger wheel on a smaller frame but the bike designers make those calls.  Don't look at wheel size when you're assessing fit.

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Tire size has nothing to do with how a bike fits!

The person who told you that is 100% full of BS!

I've spent a lot of time on this subject. I have a very nice personalized way to fit bikes for you that combines Steve Hogg, Lee McCormack, and Pete Verdone's methods that I can share with you if you really want to take the time to make your bike fit RIGHT.

Edited by mack_turtle
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57 minutes ago, mack_turtle said:

Tire size has nothing to do with how a bike fits!

The person who told you that is 100% full of BS!

I've spent a lot of time on this subject. I have a very nice personalized way to fit bikes for you that combines Steve Hogg, Lee McCormack, and Pete Verdone's methods that I can share with you if you really want to take the time to make your bike fit RIGHT.

Respectfully, I'd recommend the OP stay away from your offer.  If OP was needing to work through his original question above, then I submit he would very much be overwhelmed with your info.  He needs to learn to walk before he can run.  I'm a fan of PVD but it legit takes someone with a strong understanding of fit and geo to grasp it.

Later,
CJB

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14 minutes ago, CBaron said:

Respectfully, I'd recommend the OP stay away from your offer.

Fair enough. Starting with the right frame size is vital. If you want to get into the nitty-gritty, the methods I have in mind help a lot. But that's probably more than a beginner needs to get a bike that does not suck to ride. IMO, most people ride bikes that are way "too big" so they are comfortable in the way that a beach cruiser is comfy, but handling suffers big-time when you go too far in that direction. That's not to say you should get a smaller frame! Get a frame that a good designer made to fit someone of your hieght and riding style.

Edited by mack_turtle
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17 minutes ago, mack_turtle said:

IMO, most people ride bikes that are way "too big" so they are comfortable in the way that a beach cruiser is comfy, but handling suffers big-time when you go too far in that direction. 

Wheelbase is a killer in switchback/ledgeville, but king anywhere else that has elevation. I'll always go to the largest size that I can fit a dropper on, and thankfully modern geo has made that a lot easier.

No offense, but the O.P. just needs to dive in, and get wet at some point.

 

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11 minutes ago, ATXZJ said:

Wheelbase is a killer in switchback/ledgeville, but king anywhere else that has elevation. 

At risk of further confusing OP, "switchback/ ledgeville" perfectly describes Austin terrain. If you want to seek out flow trails with jumps and lots of elevation change per mile, a long wheelbase bike makes sense, but you need to drive a bit to find that. The trend toward long wheelbases is mostly driven by west coast riding. If I lived in PNW, I'd likely have a long bike with a low BB and raked out fork angle too.

A highly skilled rider can make anything work. Sounds like OP is going to ride mostly Walnut Creek, at least for now. If you're going to ride most of what the immediate area has to offer, a shorter wheelbase won't fight you the whole way.

But yes, OP need stop buy a bike with a frame that is roughly the right size (not a medium and not based on wheel size) and just stop farting around.

Edited by mack_turtle
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2 hours ago, mack_turtle said:

Tire size has nothing to do with how a bike fits!

The person who told you that is 100% full of BS!

I've spent a lot of time on this subject. I have a very nice personalized way to fit bikes for you that combines Steve Hogg, Lee McCormack, and Pete Verdone's methods that I can share with you if you really want to take the time to make your bike fit RIGHT.

I'd be interested in seeing your method. This isn't really something I've spent much time on, I pretty much just get on a bike and ride... But if you've got a "formula" that will get me something to try, I might give it a shot.

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1 hour ago, mack_turtle said:

At risk of further confusing OP, "switchback/ ledgeville" perfectly describes Austin terrain. If you want to seek out flow trails with jumps and lots of elevation change per mile, a long wheelbase bike makes sense, but you need to drive a bit to find that. The trend toward long wheelbases is mostly driven by west coast riding. If I lived in PNW, I'd likely have a long bike with a low BB and raked out fork angle too.

A highly skilled rider can make anything work. Sounds like OP is going to ride mostly Walnut Creek, at least for now. If you're going to ride most of what the immediate area has to offer, a shorter wheelbase won't fight you the whole way.

But yes, OP need stop buy a bike with a frame that is roughly the right size (not a medium and not based on wheel size) and just stop farting around.

Some good nuggets in here.  Your a spot-on about bike geometry being driven by the West Coast.  

-CJB

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8 hours ago, ATXZJ said:

What do you consider raked out fork angle?

 

I'm not going to put a number on it, but there's a happy medium between steep, old school XC geometry and west coast inspired long-ass bikes that works well around here. I feel like Chumba got this right with their Sendero because it's made for the terrain here. a beginner rider might benefit from geo that leans toward older-style angles because they are more likely to move at slower speeds and steer around corners rather than lean into them. so long as they can break that habit and get a bike that allows them to use those techniques later, that's helpful. starting with a bike that only comes alive on fast, curvy descents might be more of a liability.

Edited by mack_turtle
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9 hours ago, ATXZJ said:

What do you consider raked out fork angle?

 

I just ordered an angleset to add a degree of slackness to my current 67.5 HTA. Will be interesting to see if I even notice a difference at 66.5. Also swapping out forks from 51 offset to 44 offset. Both of these changes should increase trail without having a terrible impact on maneuverability, especially given my bike's incredibly short wheelbase (1181mm for Size L). Not quite the excitement of a new bike, but should be enough of a change to keep me content for a while. 

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2 hours ago, mack_turtle said:

I'm not going to put a number on it, but there's a happy medium between steep, old school XC geometry and west coast inspired long-ass bikes that works well around here. I feel like Chumba got this right with their Sendero because it's made for the terrain here. a beginner rider might benefit from geo that leans toward older-style angles because they are more likely to move at slower speeds and steer around corners rather than lean into them. so long as they can break that habit and get a bike that allows them to use those techniques later, that's helpful. starting with a bike that only comes alive on fast, curvy descents might be more of a liability.

Hard to put a stake in the ground on this one for sure.

IMHO, wheelbase is a bigger factor here than anything else. I have some experience to back this up too. At one point I owned a Process 111, Honzo and my current Hei Hei at the same time. All size L and sharing nearly identical cockpits, HTA, STA and CSL. The only real difference between the three was the wheelbase. The shortest being the honzo,  with each bike increasing around 20mm to a longest of 1220mm on the 111. No surprise the hardtail honzo was the easiest to ride here, and made it up features that the 111 really required a lot of manhandling on. The 111 felt like a monster truck around tight turns while the honzo just threaded the needle. My current Hei Hei was a compromise between the two and I sold the others.  I'm glad to see the industry steepening the STA and getting away from super short CSL while moving towards size specific geo.  See HTA below

1 hour ago, throet said:

I just ordered an angleset to add a degree of slackness to my current 67.5 HTA. Will be interesting to see if I even notice a difference at 66.5. Also swapping out forks from 51 offset to 44 offset. Both of these changes should increase trail without having a terrible impact on maneuverability, especially given my bike's incredibly short wheelbase (1181mm for Size L). Not quite the excitement of a new bike, but should be enough of a change to keep me content for a while. 

That'll be a nice upgrade to breathe some new life into your rig. I learned not be afraid to go big with anglesets or shorter steerers. My HH has a 2* bringing it down to 66 with a 40mm offset steerer. Put a 1* in my wife's HH and didn't notice a thing. Other bike will have 62-ish with 37mm offset.

I've ridden 64* on trails around here and it felt more than manageable. I guess I just prefer predictable stability over perceived maneuverability. Currently have a couple of super slacker gravity-ish summer projects in the works so we'll see how those do working the bugs out around here.

Edited by ATXZJ
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Geometry is a tricky thing, so many variables. My “trail” bike has a 515mm reach that is actually too short for me and has 450mm chain stays, so a long bike. The chain stay length feels great to me, bike feels well balanced with the longer reach. I don’t mind the long bike around here because it fits me better than previous bikes that were way too small for me. Being basketball sized it is not too hard to manhandle it around.

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  • 2 weeks later...

Good video on this topic! I'm going to spend some time figuring out my optimal true reach number. Interestingly I was out riding with my buddy yesterday who rides a 2020 Fuel EX 8 in M/L, which I just assumed would be too small for me at just under 6'. Seated I was able to make sharp turns without hitting my knees with the handlebar, and out of the saddle I was able to bunny hop pretty high at slow speed with relative ease, even though that bike is much heavier than my regular bike. I'm guessing that bunny hopping, getting up over tall ledges, etc would be easier for me on the size ML than it would be on the size L, and those are the things that are most important to me riding around here. I'm pretty sure I would feel completely comfortable on that size ML pointing down the rough and steep stuff as well. 

Regardless of what size bike you end up with, it's definitely worth taking the time to figure out optimal bar height, bar width, and stem length, all of which can be changed with relative ease and even minimal expense if you end up needing a new stem or bars.  

 

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33 minutes ago, throet said:

Good video on this topic! I'm going to spend some time figuring out my optimal true reach number. 

Regardless of what size bike you end up with, it's definitely worth taking the time to figure out optimal bar height, bar width, and stem length, all of which can be changed with relative ease and even minimal expense if you end up needing a new stem or bars.  

I've spent an inordinate amount of time with Lee McCormack's old online fit calculator. He published a book with access to it as well. interestingly, Pete Verdone has a fascinatingly simple way to measure your body's effective range of motion. then he shows you how to apply it to the bike. it looks complicated because of all the math, but it's quite simple. to make it even easier, I put the calculations in a spreadsheet: PVD_RAD_free.xlsx

The key here is that the distance between your feet and your hands is a distinct, and vital, part of how your bike fits. the distance from the bar to the saddle is also important. then there's saddle height and offset. but most of the interesting stuff that happens on a mountain bike happens when your butt is nowhere near the saddle, so start with that RAD measurement. too many people "fit" a mountain bike in a trainer with the rider sitting the whole time. that's a great way to fit a road bike, not a mountain bike.

Edited by mack_turtle
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