|Is there such a thing as proper stem length?||dawgcatchr|
Jun 14, 2003 8:03 PM
|Hi. I was wondering if a frame is typically built for an optimal stem length. For example, checking the specs for the typical bicycle manufacturer, I see that the smaller frames come stock with a 90mm stem, while the largest sizes have a 120 or 130. Since I normally ride a 55cm frame, should I look for a top tube that allows me to run a 110 stem for optimum handling? Will handling suffer if I have to go with a 100 or 120 at my size (5 foot 9).
The reason I am asking is that I am consiering purchasing either a Cannondale CAAD7 Optimo or Lemond Victorie (I work at a C-dale/Lemond shop). I am most comfortable with a 55 ish top tube-both the Lemond and Cannondale come with shorter top tubes (54.5 and 54.0 I believe, with the next size available being in the 56 range). I rode the Lemond with a standard 110 stem and it was a bit short. So, I am probably going to end up in between on either of these frames, running a 120 stem (or a 100 if I go to the next size up in either of these bikes). Will this adversely affect handling, and should I keep looking for that frame with extactly a 55 TT so that I can run my 110? Or, is this really an issue, another example myself being anal when it comes to my bicycle?
|re: Is there such a thing as proper stem length?||divve|
Jun 14, 2003 10:42 PM
|I don't think it's a problem either by fit or aesthetics to have a 120 stem on the size 54 Cannondale frame (no idea regarding the Lemond fit). If you're really set on the 110 stem you could always get the size 55 CAAD7 frameset, which has a 55.3 top tube.
Be aware that when choosing sizes so close together to take the head tube length into account. Make sure it's not too short necessitating too much stack height (significantly increased flex with a carbon steerer) or slightly too long leaving you with no possibility to lower your handle bar without changing to a tighter stem angle (80 deg. is pretty much standard).
For the remainder the CAAD7 54 and 55 have similar geometries with the exception that the smaller size has a slightly sloping top tube for additional stand over height.
|re: Is there such a thing as proper stem length?||SLR|
Jun 15, 2003 12:03 AM
|I'm 5'9" too and my TT is 54cm, My stem measures 115mm C-C and I have a set back setpost. I think going to a 120 stem will be fine for you. I was fitted and my optimum TT length is 54.5. The frame I bought comes in a 54 or 55.3 TT, after much debate I went with the 54 and a little longer stem cause I didn't want to be too streched out on the 55. BTW the head tube lengths were the same too.
Jun 15, 2003 5:19 AM
|The idea that one particular stem length is ideal is nonsense. I've used 100,110 and 120 stems on the same frame, depending on where I had the saddle fore/aft adjustment set.
Unless you were very lucky, it's unlikely that your saddle fore/aft position was set at the ideal position when you test rode the Lemond. It always takes me several hundred miles of riding to completely settle on an "optimum" saddle position. Until the saddle position is optimized, the appropriate stem length can't be determined.
Comparing TT length without taking into account the effect of differing seat tube angles is also a mistake. In the case of the Lemond (53) and C'dale (54) the difference in STA is a very small .25 degree. Both have the same advertised 54.5 TT length, but the effective TT length of the Lemond is actually 54.1cm, taking into account the difference in STA.
When you've had enough years of riding, you should be able to determine a particular set of dimensions that you consider "ideal". From those dimensions, it's easy to compare other frames and determine what will be required to make it fit properly.
For example, I just got a new frame with a 73.5 STA and 53cm TT length, although I had been riding a frame with a 74 degree STA and 54cm TT for the last several years. The head tube of the new frame was also 1cm shorter than my previous frame.
The "effective" top tube length of the new frame was actually 52.4cm, or 1.6cm less than my previous frame, taking into account the difference in STA. Since the reach on my old frame was "plenty long", I selected a 1cm longer stem (rather than 2cm). I also knew that a 1cm spacer would be required under the stem to achieve the same bar height. When I built the bike, I cut the steering tube to the exact length needed the first time, and only had to make saddle fore/aft adjusments during the first few rides to complete the setup.
I now have one frame with a 100mm stem and one with a 110mm stem. The fit on both is nearly identical.
Jun 15, 2003 5:48 PM
|A shorter stem will make the bike slightly more responsive to steering input (the same amount of handlebar movement will give more turn of the wheel) and (all else equal) shift the center of gravity back a small amount. Use the stem to get proper reach, once you have your saddle in the right place relative to the BB. There is no right length. Smaller frames tend to have shorter stems, but that's because their riders have shorter torsos.|
|re: Is there such a thing as proper stem length?||weiwentg|
Jun 15, 2003 4:30 PM
|from what people on this forum have posted previously, Eddy Merckx always insisted that his bikes have 110mm stems. that said, Eddy Merckx is Eddy Merckx, and you are you.|
|re: Is there such a thing as proper stem length?||kai-ming|
Jun 15, 2003 5:22 PM
|Some coach said the optimum stem length is 100-120mm. I had been using 90mm, it was a bit touchy at first but got use to the set up afterward.|| |