What size mountain bike frame do I need if I ride a 56cm bike?

[mtechnica]

54 is way too small. 55 is too small. 56 is perfect. I can ride 57. 58 is definitely too big. What size mountain bike frame (inches) should I be looking for? My saddle height is 785mm.

[bart998]

I am pretty much exactly the same fit as you... same frame, same saddle height. I also have a mtn bike. It has 27.5 wheels and a large frame.... I think a medium would fit me better. but the large is ok.

[jtakeda]

I would test ride a few bikes.

It’s hard to say without knowing which specific mtb you’re looking at.

Also it depends on how you ride and what time of terrain.

I ride a 55cm road frame and am perfectly comfortable on a size L mtb with short stem and wide bars. I have long legs for my height (57 st 55 tt on the road bike). I’m not exactly doing Red Bull trails at blistering speed though.

Need more info

[Jaybee]

Totally dependent on manufacturer and whether you are looking for an XC or trail bike fit, IMO. I'm 56/57 on most drop bar bikes, and I ride a large or 19" in some manufacturers, an XL or 21" in others. My XC rig has 440mm of reach. My trail bike is 451mm. Also make sure you have enough seat post extension for a decent dropper, if that's the flavor you are looking for.

[vqdriver]

there's no right correlation because road bikes are fit (more or less) statically whereas mtb fit is highly dynamic, so a numbers to numbers translation doesn't work well.

it's complicated by the different suspension setups and bike types. an xc bike and an enduro bike will feel different in the same size, even from the same mfg.
i'd start with a M or L and go from there.
best way is if you can demo a bike because parking lot donuts don't always say much either.

[yakstone]

Start with a medium MTB as a baseline.

[mtechnica]

Basically I want a 29er for XC, I do a lot of climbing which means going back down hills too, so I figure I’ll need a dropper post.

[45K10]

Basically I want a 29er for XC, I do a lot of climbing which means going back down hills too, so I figure I’ll need a dropper post.

I'm basically the same seat height and I ride a Medium Niner hardtail. But a Medium in a Trek would probably be too small for me. So you'll need to check to the manufacturer's geo chart.

[BikeNY]

Basically I want a 29er for XC, I do a lot of climbing which means going back down hills too, so I figure I’ll need a dropper post.

I'd say start with a large and see how it feels. As others mentioned, different manufacturers measure and size differently, so it really depends.

And no, you don't need a dropper! If the trails are really steep and technical, you may feel more comfortable with one, but they can be ridden just fine without it. Mellower trails do not need one at all. Just adds cost, weight, and maintenance.

[eippo1]

I also ride a 56 and prefer a 56.5 TT with a short stack. So thinking that I like an aggressive position, got a size M 17.5 full suspension short travel mtb and was miserable riding the thing.

Rode a couple large full suspensions recently and felt like I was in the bike rather than on top of it and had no issues getting it to do exactly what I wanted. So upgraded to a medium Stumpjumper ST Comp this fall and am way happier. Thought it was pretty telling since I live across the street from the Fells (no really, actually across the street) and barely went riding there. Already been on a few rides there despite terrible weather we've been having and just getting the bike recently.

Also modern mtbs fit a bit differently than they used to, if you straddled the line between M and L before with a trial bike, you'll most likely want to go with a larger size due to how they ride now.

[mtechnica]

It kind of sounds like I’d be happier on a bigger frame, so maybe “large” would be the most appropriate, but considering that the sizes name doesn’t necessarily indicate any particular measurement, what should I look for in the geometry chart that would indicate whether a particular manufacturers medium or large is what I need?

[Cat3roadracer]

18".

[thedvlsh1]

Beside getting fit @ your LBS I recommend using Competitive Cyclist's fit calculator --> https://www.competitivecyclist.com/Store/catalog/fitCalculatorBike.jsp

[Jaybee]

It kind of sounds like I’d be happier on a bigger frame, so maybe “large” would be the most appropriate, but considering that the sizes name doesn’t necessarily indicate any particular measurement, what should I look for in the geometry chart that would indicate whether a particular manufacturers medium or large is what I need?

Seat tube length is almost meaningless for MTB fit, even though it's what a lot of manufacturers list for bike size. I'd use reach (somewhere between 440 mm and 455 mm) or maybe effective top tube (somewhere between 620mm to 640mm) to get in the ballpark. Unless you have really end-of-the-bell-curve proportions, you should be able to adjust from there.

Narrow down some targets and get some dirt time on those bikes if at all possible. It's pretty challenging to find a "best" MTB just based on numbers. Much harder than road bikes.

[eippo1]

Yeah, agree with above -- ride a couple. XC, trail, and long travel all ride and fit differently.

[mtechnica]

I’m not really sure how I’ll get an opportunity to test ride a variety of mountain bikes to my satisfaction so my plan so far is to try to get a good estimation of what I think I need and ride it for a while, then re-evaluate after I actually learn how to ride a mountain bike and see where my preferences lie.

At this point I’m debating between building up a frame or trying to buy a complete, but there are so many different options I’m at a bit of a loss except that I know I want a relatively light 29er with at least a front shock and modern geometry. I’m not sure if I want or need a full suspension but it could be nice to have.

I’ve been riding my cyclocross bike with 45c tires on some of the popular mountain bike routes in the area and it’s not ideal hahaha.

One thing I can say for sure is that I’m not going to do jumps or bomb down hills.

[jtakeda]

There’s no shops that rent bikes?

No friends that can let you borrow a bike?

Maybe come to Santa Cruz and demo an ibis and a Santa Cruz and you’ll get an idea of your fit

[93KgBike]

The used mtb market is pretty inviting right about now. Good deals on several generations of Santa Cruz's. I'd say med or large depending on build. GL

[mtechnica]

The used mtb market is pretty inviting right about now. Good deals on several generations of Santa Cruz's. I'd say med or large depending on build. GL

Any thoughts on things to look for? I’d prefer Shimano and will probably have a budget of ~ 1500 when I’m ready to buy.

[Jaybee]

I’m not really sure how I’ll get an opportunity to test ride a variety of mountain bikes to my satisfaction so my plan so far is to try to get a good estimation of what I think I need and ride it for a while, then re-evaluate after I actually learn how to ride a mountain bike and see where my preferences lie.

At this point I’m debating between building up a frame or trying to buy a complete, but there are so many different options I’m at a bit of a loss except that I know I want a relatively light 29er with at least a front shock and modern geometry. I’m not sure if I want or need a full suspension but it could be nice to have.

I’ve been riding my cyclocross bike with 45c tires on some of the popular mountain bike routes in the area and it’s not ideal hahaha.

One thing I can say for sure is that I’m not going to do jumps or bomb down hills.

If you are this new and willing to do this as an iterative process, then I think you could do way worse than the following:

1) Get some parking lot rides in on whatever major brands are carried close to you (either at an LBS or on Craigslist or whatever) in size M or L. You can get some sense of what bikes fit and which are complete no-go's just by riding around the neighborhood.

2) Everyone has a HT 29er, the specific differences between say, a Specialized Epic or Chisel, Trek Procaliber, Salsa Timberjack, Santa Cruz or Kona whatever aren't super important. Pick whichever spec/color you like. There aren't very many bad MTB out there, especially HTs, so pick with confidence.

3) Ride this for a few months. Evaluate where you are with riding skills, what tires and drivetrain bits you like. Fiddle with your fork knobs and pressures. Maybe try a dropper, maybe don't. Develop personal experience.

4) You now know enough to be a better informed shopper about what works for you. Go back to your LBS and tell them what you like and don't like about your current bike. Maybe you just need a bigger fork, maybe some fatter tires or less knobby tires. Maybe you are ready for a whole new bike. But at least you have your own experience to tell you this.

Enjoy, MTB is fun. Way more fun than road, IMO. :fight:

How to Buy a MTB (https://www.youtube.com/watch?v=yotOZVELSMc)

[John H.]

Size will be specific to the bike, terrain, and riding style.
But I would call 785mm saddle height a large any day of the week.
My saddle height is closer to 730mm, I am a medium- But I could go large on some bikes.

[93KgBike]

The Tall Boy, the Blur, even the older Superlight (vpp) or the original single pivot climb exceedingly well. There are many others, and a strong rider can enjoy any good bike, but I've never enjoyed xc climbing more than on one of these.

I just checked the bay, and really need to look away. Good selection at the low$ end. Right at your $point for example (no affiliation):

https://i.ebayimg.com/images/g/CL0AAOSwMflcDZAL/s-l1600.jpg

[eippo1]

All really good recommendations from above. I'd also second what most are saying re: second hand or buying new and then fiddling with the spec. It's relatively easy to build up with a road bike, but buying piece by piece in the mtb world for everything will cost way more $$ than it's usually worth.

[BikeNY]

What kind of trails are you planning to ride? Are they really rocky and technical with lots of rock gardens and logs and such? Or smoother with only the occasional technical feature? That should give you some direction on bike type. HT vs FS.

There must be shops around your area that will at the very least let you ride a couple of bikes around the parking lot to get a feel for the right size.

In your situation, I think a hardtail 29er with the biggest tires that fit makes the most sense. Ride that for a season so you have some idea what kind of trails you like, what you like about the bike and what you don't. No point in spending even more money on a bike that may not fit right, may not be the style of bike you end up liking, etc. You may end up not even liking mountain biking!

[mtechnica]

Most of the riding I do is on relatively smooth trails, like I’ve said I’ve been managing on a cross bike although downhill can be really slow going without risking going over the bars - lol. Lots of climbing though, and I would say comfort is a big priority since I like the smooth feel of road riding and don’t enjoy getting bumped around all day, which is why I’d consider FS.

[Hilltopperny]

I have a nice Trek procaliber 9.8 sl in 18.5 which is basically a medium large and would probably be the perfect bike for your size and needs. I am also looking to clear it out for $1,800 shipped if you are interested.

Sent from my XT1650 using Tapatalk

[danesgod]

What kind of trails are you planning to ride? Are they really rocky and technical with lots of rock gardens and logs and such? Or smoother with only the occasional technical feature? That should give you some direction on bike type. HT vs FS.

There must be shops around your area that will at the very least let you ride a couple of bikes around the parking lot to get a feel for the right size.

In your situation, I think a hardtail 29er with the biggest tires that fit makes the most sense. Ride that for a season so you have some idea what kind of trails you like, what you like about the bike and what you don't. No point in spending even more money on a bike that may not fit right, may not be the style of bike you end up liking, etc. You may end up not even liking mountain biking!

I agree with considering what kind of riding you're doing, and being realistic about it :). I came from a BMX background so a small-ish, squirrel-y bike was a good first choice for me, I got a ~2008 santa cruz chameleon. It jumped super well coming from BMX, but was harsh going into similar "level" rock gardens. I've since moved up to a longer, slacker, trail/jump-y oriented bike with a plush shock, making "hard" rock gardens more straightforward than the older hardtail.

Point being, if you're jumping or came from BMX, go medium (fit will probably small-ish on you). If you want a boat with stability for plowing through chunder, go bigger. If you're riding XC, 29er hardtail is probably a good bet at a good price.

TL;DR - a hardtail, older generation bike around the ~$500-1000 will serve you well, and could be resold with minimal loss of value if you hate it or want something fancier in a year.

[Jaybee]

I have a nice Trek procaliber 9.8 sl in 18.5 which is basically a medium large and would probably be the perfect bike for your size and needs. I am also looking to clear it out for $1,800 shipped if you are interested.

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Ive seen this in the classifieds. It's a really nice bike that I would be all over if I didn't know that I'm definitely a 19.5 in this particular model.

[jtakeda]

Size will be specific to the bike, terrain, and riding style.
But I would call 785mm saddle height a large any day of the week.
My saddle height is closer to 730mm, I am a medium- But I could go large on some bikes.

+1 here.

I’m a 745mm saddle height and consider myself a medium but I’m riding a large no problem.

[zambenini]

I feel compelled to add: it's a different sport with a dropper. You want one for fun's sake. Whatever kind of bike you get. You won't regret it.

While I'm generally a retrogrouch about bike tech, modern MTBs rule compared with the rim brake 26er I started on. Droppers are a good development.

[mtechnica]

I have a nice Trek procaliber 9.8 sl in 18.5 which is basically a medium large and would probably be the perfect bike for your size and needs. I am also looking to clear it out for $1,800 shipped if you are interested.

Sent from my XT1650 using Tapatalk

Wish I could take you up on it but I haven't saved enough to buy anything quite yet :(

[adub]

Curious how stack/reach numbers translate from road to MTB?

I would think that you want a shorter reach on a MTB all else being the same?