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Frame Size...how big is too big?(23 posts)

Frame Size...how big is too big?jwhite480
Jan 8, 2003 7:00 AM
I am looking for a new bike to ride longer rides and maybe do a little weekend touring (not heavy). I looked at several bikes and found that I was more comfortable on the larger frames (while riding) but they hit me in the crotch area when I was standing up. I measured out to be a 51-52 but the 54 bikes just seemed to fit better on a ride. I have a typical german build with a very long upper body and short legs. Do you recommend to take the bigger bike since 99% you are riding and not standing on the bike, or buy the mid size and change stems, etc??
Try this:djg
Jan 8, 2003 7:15 AM
Go for another test ride on the 54. Stop two or three or six times along the way. If you can stop comfortably (likely by tilting the bike some--which you would do to some degree in any case) then take the larger, more comfortable bike. You really want to be comfortable while riding, and can probably mount and dismount safely with limited clearance.

OTOH, if you can't, you can't. If you find yourself banging the gong a lot, look for another solution. Different stem, another spacer, compact frame, custom frame, etc.
re: Frame Size...how big is too big?rwbadley
Jan 8, 2003 7:33 AM
Go for the larger size...
I am ideal on a 56cm. I have rode any size on up to a 64cm for recreation and let me tell you, you just get used to it.

It's kinda nice to be able to sit on the top tube at stoplights 8-), and I think sometimes the larger frames ride a little better.
I am not saying correct fit is not important, but in the size your looking at, I would go for the 54cm

RW
Good question . . . (long answer)Look381i
Jan 8, 2003 7:41 AM
I suspect that your upper-body comfort was due to either or both of two factors associated with the larger frame: a higher bars position relative to the saddle and a longer top tube. You might be able to achieve the same high bars position on a smaller frame with spacers under the stem or a higher angled stem. You might be able to effectively lengthen the tt cockpit with a setback seat post and/or a longer stem.

Assuming you could achieve the same comfortable upper body position of both sized frames, you still need to pay attention to your lower body. Many advise that a starting point, after setting seat height properly, is to see whether your knee (the bony protuberance just below it) is directly above your pedal axle when your foot is forward in the 3 o'clock position -- the so-called KOPS standard. That will give you a relatively neutral starting point. A rearward position usually gives more power; a forward position, more leg speed. If your saddle still has for-aft adjustment, you can later fine tune your preference.

My advice is to find a frame and set up that will allow you to replicate or improve the comfortable position of your current ride and that allows fore-aft and up-down adjustments of saddle and perhaps stem to tweak it as you ride longer. Modern stems are easy to change.

As for standover clearance, I think that is over-emphasized in bike fit and safety. In the early years of bikefitting, it was a proxy for the crucial fit measurements. Having an inch or two of clearance was thought to man that the frame fit and a saddle adjustment would dial it in. Given frame geometry variations and body proportion variations (like your shortlegs), it's no really reliable in fitting. Nor is it especially important for safety.

If you have the top tube, seat tube and stem lengths, saddle-to-bars drop and saddle position dialed in for your riding style, then you'll likely have several inches of seatpost showing and some standover clearance. But even if you don't have much or any, it's no big deal. When you stand, it will be usually be with one foot clipped in, one on the ground and the bike tilted. If you come off suddenly, it will be to one side or the other, not straddling the top tube with the bike perfectly upright and with your feet dangling in the air.

Given your proportions, look for a frame with a longer top tube than seat tube. Lemonds and Looks, among many others, fall into that category.

Good luck.
I second the LemondAlpedhuez55
Jan 8, 2003 8:15 AM
I have the same short legs, long torso build. I found the Lemonds fit me best. I was going to go custom but the measurments would have come up the same as a 55CM Lemond. 53 may work well for you.

Mike Y.
Where's a good place to buy one?jwhite480
Jan 8, 2003 9:58 AM
I asked my LBS about a Lemond and all I got was that deer in the headlite look......guess that is what I get for living in southern Ohio
Have you looked at a large compact frame?Dave Hickey
Jan 8, 2003 8:08 AM
A large compact frame might be what you need. It will give you plenty of standover room and have a long top tube for your long torso.
Tell me more!jwhite480
Jan 8, 2003 10:02 AM
Dave,

Thanks for the input. I am really new at this and trying to buy my first road/touring bike. What is a large compact frame and where do you get them?
Here is an example.Dave Hickey
Jan 8, 2003 11:07 AM
Giant and Specialized are the big players with compact frames. Here is an example of the Giant OCR1. As you can see, the seat tube is very short in relation to the top tube.
OH, I seejwhite480
Jan 8, 2003 11:23 AM
Ok, then with the top tube slanting down I could buy a larger bike and still have sufficient stand over room.

thanks
two bird with one stonelaffeaux
Jan 8, 2003 11:28 AM
Find a good Trek dealer in your area. Hopefully they also sell Lemond and Klein (which are both Trek brands). The 2003 Kleins come with compact geometry and are a great price, and the Lemonds do have a longer top tube. Ride them both and see what you think.
54 cm is too bigMR_GRUMPY
Jan 8, 2003 9:03 AM
What you need to do, is to find out what the top tube size was on the 54 cm frame, and then find a 52 cm frame with that top tube length. It might not be easy, but a 54 frame is too big for you. If you can't find the proper frame, you might just need a custom.
clearance defined...C-40
Jan 8, 2003 9:13 AM
A minimum of 2-3cm of clearance to firm, saddle-like crotch contact is generally recommened. With this minimal clearance, the top tube can still lightly brush the crotch of cycling shorts.

Another good check is to measure the height of the saddle above the top tube. I like mine to be about 17cm. Less than 15cm would indicate that the frame is (vertically) too large.

Changing from a 54cm to a 52cm frame generally requires a 1cm-2cm longer stem to produce the same reach to the bars and a steeper angle on the stem to raise the bars 2cm.

If you are test riding frames, remember that you aren't stuck with the stem length that comes on the bike. With a long torso, you may need to increase the length to 12cm, perhaps more.

As for Lemond frames, their top tubes are no longer than most other brands in this size. LOOK frames have about the shortest top tubes that you will find.
Need explanation about tt lengthsLook381i
Jan 8, 2003 2:39 PM
Your statement confuses me: "As for Lemond frames, their top tubes are no longer than most other brands in this size. LOOK frames have about the shortest top tubes that you will find."

Lemond geometry is 51 (53.2 tt) and 53 (54.5 tt). The Look is a little longer in the top tube in those sizes: 51 (54 tt); 53 (54.8 tt). They have similar, laid-back STAs (and HTAs), not as steep as say Trek or Colnago.

Lemonds, Treks and Lightspeeds are the most popular road frames where I ride. I'm the black sheep, with a Look, a Colnago and a Guerciotti. Having ridden my friends' bikes, and they mine in similar sizes, we have generally agreed that my Look and their Lemonds have longish top tubes, with the Treks, Guerciotti and Colnago going shorter. In other words, achieving a cockpit length comparable to Look and the Lemonds with the latter frames requires bumping up the size (st length), using a seatpost with more setback and/or lengthening the stem. (When I buy a frame and build it up, I carefully measure to assure that I can replicate my preferred position. I usually begin a fit by focusing on tt length.)

For example, to achieve the same position on my 54 Look and Guerciotti, I must use a Campy seatpost with the Guerciotti (Instead of the Look's USE Alien) to make up for the Look's 1.6 cm longer tt. I use the same stem length and angle. To achieve the same position on my 56cm Colnago (Dream Plus), with its 54.8 tt, about halfway between the two, I adjust the saddle slightly.
re: Need explanation about tt lengthsthe other Tim
Jan 8, 2003 3:07 PM
I don't know about Looks, but a LeMond 53 is about the same as a Trek 56 (standover) which would make the Trek's top tube longer than the comparable LeMond's.
Effective top tube length...C-40
Jan 8, 2003 6:36 PM
In your comparison, you have failed to take the differences in seat tube angle into account. The LOOK frame has a 72.5 degree STA while the Lemond has a 73.25 degree STA. If the saddle is located to place the rider in the same position on both frames, the effective top tube lengths of the LOOK frames are reduced by .9cm to 53.1cm for the 51cm size and 53.9cm for the 53cm size.

Here's my canned writing on the topic. The formula used to calculate the effective top tube length is included:

The effect of seat tube angle (STA) on top tube length can be expressed simply. The idea when comparing frames is to maintain the same body position relative to the bottom bracket while comparing any difference in the reach to the handlebars. If two frames have the same STA, the actual TT length will be an accurate comparison. For instance, if the both frames have a 74 degree STA, but one has a 55cm TT and the other has a 56cm TT there is a difference of 1cm in the reach to the bars. If the STA is not the same, this comparison would not be accurate. Here's why:

On a frame with a 74 degree seat tube angle, the saddle must be moved further back than a frame with a 73 degree seat tube angle to achieve the same rider position relative to the bottom bracket. This movement of the saddle must be accounted for. Since the TT length is the standard reference value for comparing the reach to the handle bars, the difference in SADDLE POSITION is added or subtracted from the actual TT length to produce an "effective" TT length. The effective TT length will accurately predict the difference in reach to the handlebars between any two frames and allow you to determine the difference in stem length that would be needed to maintain the same reach. When comparing frames with different STA, add TT length to the frame with the steeper (74) angle OR subtract length from the frame with the shallower (73) angle, using one of the following formulas: 1.32 x (cosA-cosB) x frame size, or an alternate formula, saddle height x (cosA-cosB). An average amount is 1.2cm per degree for a midsize frame.

The explanation for the 1.32 constant is simple. It's merely a way of expressing (approximate) saddle height in terms of frame size. Frame size (c-t) is .67 times inseam and saddle height is .883 times inseam. Expressing saddle height in terms of frame size, you get .883/.67 =1.32 frame size.
Why do you ignore the HTA differences? (nm)Look381i
Jan 10, 2003 8:40 AM
Try compact geometryjtolleson
Jan 8, 2003 9:54 AM
Most compact frames have a relatively long effective TT while still allowing good standover clearance. They are a nice option for the shorter legged, longer torsoed rider. I bet a medium compact would give you a lot of the fit that you liked in a 54 without the compromise of standover.

Maybe the new steel Specialized? Also Giant is a nice option in compact bikes (you didn't mention your budget).
One testicle on each side of the top tube is too big (nm)grzy
Jan 8, 2003 11:48 AM
...especially while pedaling (nm)DougSloan
Jan 8, 2003 8:10 PM
The testicle is too big or the bike is too big? (nm)mickey-mac
Jan 8, 2003 9:20 PM
nm
If you think you may train on rollers someday...joekm
Jan 8, 2003 11:49 AM
make sure you have adequate standover height. One day, your going to miss the roller frame and wish you had a smaller bike. I speak from experience on this one.....
re: Frame Size...how big is too big?Trent in WA
Jan 8, 2003 4:33 PM
I'm largely in agreement with Look381i here. One thing to keep in mind is that most contemporary frame fit formulas assume that you're going to be riding in a more-or-less racing position and will be using as much drop to the bars as you can handle, the better to achieve an aero position. Larger bikes will make it easier to get your bars close to saddle level, which might be just what you need. And with the bars closer to saddle level, you can run a longer stem and maintain the same cockpit length. If that's the case, don't worry about what the formulas say. There've been a bunch of formulas developed over the years for bike fit, but they all are based on assumptions about intended use that might not hold in a particular instance.

Hope this helps,
Trent