Does frame size really need to be exact?
 

I'm a tall guy (6'3") and I currently ride a road bike that has a 62cm DT and 58cm TT. I like to ride kind of upright so I like the 58 cm TT, I could even maybe raise it up a bit, but the quill is already at max.

I'm looking at getting a Surly Cross Check (for commuting) and I'm torn between the 58cm and the 60 cm. The geometry of the cross check is that the DT = TT. So I feel like I need the longer DT but don't want to increase the reach on the TT.

But with all the different lenghths and slopes of stems does it really matter. If the 60cm has too long of a reach couldn't I just get a shorter stem. Or if I get the 58cm and need to raise the seat up really high, couldn't I just get an upsloping stem, and even a stem extender if I need to, to achieve a more upright riding position?

So as long as I am in the right ballpark and not trying to ride a 52cm frame... does the size really need to be exact?

I'm your height, and I passed on a Surly because 60cm was the biggest they could get. It was just too small. My two main bikes, an Atlantis and Rambouillet, are 64s, and if I had it to do over, I'd probably go up to 65 (Rivendell recommended that, but they didn't have them in stock and I was eager).
Before I got those, I rode for 15 years and thousands of miles on a couple of 62cm frames, the largest most shops stock. They like to sell what they have, and they promised longer seatposts and stuff to "make it perfect." They were both rideable, and at the time--until I got the Atlantis--I thought I was as comfortable as you could get on a bike. There are other factors that make the Atlantis and Rambo comfortable (higher bars, Brooks saddles etc), but size is part of it. The first time I sat on the Atlantis, I was able to spend 25 percent more time in the saddle without discomfort than on my previous ride.
You may be able to make the Surly work, but my advice is to figure it out BEFORE you pay for it. Otherwise you just get another place to hang rags in the garage.

I am taller too...6'2" with long arms and legs. Getting any bike dialed in is a PITA. My road bikes are usually in the 64-65cm range, don't recall what my tt is, but I typically run 110mm stems about even with the saddle. Ride the bike that is the most comfortable for you, and don't be afraid to swap components to get what you need.

Aaron :)

Lennard Zinn is a tall guy , builds custom bikes, writes for velo news, Q&A tech column,
and writes books ..
might be a Good resource to draw upon ..

If the geometry from your current bike is correct, then the 60cm frame would be the correct choice as you could easily compensate for the 20mm differences by using different stems and having more seatpost showing. With the 58cm frame you would have a much harder time getting the bars as high as you would like. For reference, I am 6'1" tall and I have been able to ride both the 58cm and 60cm Crosschecks comfortably and I prefer my bars to be just slightly below seat level.

No, the size doesn't have to be exact, but you can spend lots of time and money changing stems, bars, and seatposts with more or less setback to make up for a bad fit.

Hi. I'm 6'4. on 63. I think it is not depending on how tall you are, but how long is your reach and how flexible your body is. Also for what you ride the bike. In this case you're clear that you want upright one. So my suggestion is to get 58 and put a longer front fork.(Might be a lil bit weird looking though...)

For seat post, You may be able to use longer one to adjust fitting, and it doesnt really matter as long as the very end of your seat post is located lower than where TT meets DT. (NEVER locate it higher than TT height.)

BTW, I like Wrench Science's fitting system. Chose either Road or MTB and you'll see "fitting system" in menu at the top. You may refer what size fits you and you can adjust from that.

http://www.wrenchscience.com

why is that? couldn't I just use an upsloping stem, or a stem extender?

I don't think I understand this. Could you please explain it more? Does it mean the seat post must be sticking down the seat tube so that the end without the saddle is lower than where the TT meets the DT?

Sorry if my explanation was unclear. For this point, drawing can tell easier. Left one is how it is supposed to be. center one...not really appreciable, right one is the bad example.
http://bikeforums.net/attachment.php...hmentid=172969

This is how my friend's frame died.
http://bikeforums.net/attachment.php...hmentid=172972

Have to agree. After 16 years on MTB's I know what fits me- but 4 years ago I went road. Knew what I wanted but tried the bike I felt comfortable on and the next size up. The larger one felt too big. So bought the size I was comfortable that in Giant Sizing equates to a 49 to 51. Wasn't long though before I realised I was a bit cramped. The bars were too low and I was not comfortable. Adapted it with the seat way up high and a longer stem with a lot of rise in it

Attachment 172978

This bike fitted OK but it was not really comfortable. but it sufficed. A year later and I was up for a better bike and got a Conventional frame in 51 sizing. This was a race spec frame and the longer- laid out position of the lower bars works. Did not believe it when the shop told me to go out and ride it but this bike is comfortable.

Attachment 172979

Still a Giant man at heart and the shop got me a good deal on a TCR-C but in the next size up to the OCR. This is a 51 to 54 Fits far better than the 49 to 51 but the bike out of the 3 that fits best is the conventional 51. But I think a lot of that is down to the geometry of the bike when compared to the TCR. I do like the feel of that bike.

Attachment 172980

So 3 bikes- all sized 51- and they will fit. Difference is in Geometry

So don't just look at the sizing- try bikes of different Geometry. Comfort- Performance or Race geometry will also have a bearing on the fit.

There's upright and there's upright. When I hear "upright", I think Dutch city bike or bike path hybrid.

Do you mean you want something that's less low than a racing position, or do you mean you want to sit up straight like a Dutch city bike? Those are the extremes of "upright". Where you fall between them determines whether or not the Cross Check is the right frame geometry to begin with.

If you define for us what specifically you mean by upright, you'll get much better answers.

The Cross Check, as with most cyclocross bikes, is designed for riding with your torso at around 45° to the ground and your arms around 90° to your torso--a little lower or a little higher, but in that neighborhood. This is upright as compared to a road racing bike, but not when compared to a Dutch city bike. The geometry of the bike determines the handling. Handling is hugely influenced by weight distribution, and weight distribution is determined by position.

Yes, you could take a frame like the Cross Check, size it small and put all sorts of funky extensions on the front end to make your position similar to a Dutch city bike. But the bike won't handle like it's supposed to, nor would it handle like a bike designed to be ridden in that position.

Long story short, position determines weight distribution, which determines geometry. By choosing a geometry first, then trying to change your position, I think you've got the cart before the horse.

The biggest problem with the Cross Check is its distribution model. Any dealer can order one, but few stock them, so you can't really test ride one. Those of us in the middle size ranges can, with experience, pretty much order a frame without having ridden it first. Shorter and taller folks have a much tougher time of this, and really need a test ride.

No, frame size doesn't need to be exact, or we'd all need custom frames. But I think you are mistaken to think that the larger frame automatically means a longer reach. With the 58 frame the head tube will be shorter, so the drop from saddle to bars will be bigger. That will put you in a more aero position than you would be in on the 60 frame, because while the saddle will be at the same height (obviously - your legs will still be the same length) the bars can be higher because of the taller headtube. So even though the top tube will be longer, you'll likely feel that you are reaching less far because you'll be in a more upright and therefore probably more comfortable position.

Lots of pros ride frames that I would consider too small, because they have no trouble with the very aggressive aero position and it gives an advantage. Personally I couldn't handle it over very long distances. I too am 6'3" and I have bikes of different sizes. My touring bike is about 61cm, my road bike about 60, and I have a 58cm fixie that I'm comfortable on but I probably wouldn't want to ride it round the world. So what works for you will depend very much on the position you want to be in and the geometry of the individual bike. Try both, buy the one that feels right.

Thanks for all the great advice.

As far as "upright" I and thinking of something between comfort and racer... maybe around 40 or 35 degree. And I would like to have some bend in the elbows so my arms aren't out straight. Definitely not Dutch upright though. I tried my friends 56cm racing bike and I hated the aero postition and the really long reach... so that is what has me so worried about the TT length.

The Cross Check seems to have the kind of geometry I would want, and I really like that it has the rack and fender eyelets. When tsl says that arms will be 90 degrees to torso, that mean they will also be straight out... or the upper arm will be at that degree but the elbows will be bent?

Unfortunately before I started this thread and gave it more thought I had decided 58 cm would be perfect and was bidding on one on ebay :eek:. Luckily I lost that auction, and I'm planning on going with a bigger frame.

What geometry do you guys favor for non-racing, general riding and commuting?

Elbows always bent.

The Cross Check may be the right bike for you then.

My primary commuter is based on cyclocross geometry in the front, (touring in the rear) and it's just about perfect for they way I ride and how I want a bike to behave in traffic. The relaxed front end is what you're getting out of the CX geometry. That will go towards your preferred position.

The larger frame also has a longer head tube, which also goes towards your preferred position. Bikes for tall guys all have long head tubes, but the top tube doesn't usually seem to lengthen at the same rate. In other words, generally you get more height than length in a larger frame, which is exactly what you described as your desire in the OP. Although now that I look at CC numbers, I see they keep it square all the way up. Still, an extra inch of headtube will be a good thing for you.

Gee, all these years I thought sizing was determined by the length of the Seat Tube (ST), and the Top Tube (TT).
Now I just learned I should have been measuring the Down Tube(DT).:twitchy:

Shame,,,,DT in all of my post meant ST. I've been riding bike for more than 10 years and been misunderstanding DT as ST, and ST as DT....It's sort of miracle isnt it....urgh!!

I didn't even notice you were calling it the wrong thing (the brain just corrects for some things when you're reading). I knew you were talking about the ST.

Depends. I often commute on my tourer, less because of the more relaxed position than because it allows me to carry clothes, laptop etc. If I had to keep just one of my bikes the tourer would be it, precisely because of its versatility and all-day comfort.

For long distance rides on which I want to go reasonably fast I have a Giant SCR carbon (the predecessor to the Defy Advanced) which I use in preference to my Giant TCR because it has a slightly longer wheelbase, more like a Roubaix; and I'm getting a bit old and inflexible to be comfortable on the TCR for 100 miles at a time.

And for JRA, and as a winter bike, I'll use my fixed gear, which apart from the brakes (I'm very un-hip) is set up pretty much as a track bike.

I have 4 different road bikes, The OCR- (SCR in the UK) is fairly relaxed geometry but a bit on the small side so unfair to bring it in. Bike of choice is the Boreas Ignis that is a full race geometry. The long stretched out ride position suits me but have to admit that it is not a 100 mile ride. I use this up to around 65 miles but after that I do get a niggle in the back and if it is hilly then the Compact Crank is just a tad too high on the longer rides. I have set up the TCR-C with a triple and I use this on the long rides. Bars just a bit higher and lower gearing. Then I do have an unusual bike. A Giant FCR1 (Same frame and Geometry as the OCR) with drop bars and a compact 9 spd. This is the bike for the mountains as it is set up with an 11/34 cassette. It will climb a wall if necessary but Who wants to climb a wall?

So different bikes for different uses and there is no favourite. Favourite for a use- yes but No favourite.

If I had to go with just one bike for all uses- It would be Boreas- but fit a triple on it and get a stronger set of wheels.

Consider using a "lay back" seat post (solid aluminum bar stock!) to help you adjust the bike to a more upright seating posture.

So I ended up buying a 62cm Surly Cross Check frameset, but it is going to be my winter/spring project to actually find the components and parts to build it up. So it will be a while until I know how much I like the fit. But from reading here and other places it seems like the longer reach will be more comfortable than the lower (but shorter) reach of the 58cm frame. And it seems like the bike will handle better if I don't try to modify the fit by putting on a really upright angles stem and a bunch of spacers.

Thanks for all the input.