|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
I need a bike with a top tube of about 50.5 cm. To get a top tube of
that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? |
Ads |
#2
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
I would say the LBS is mostly correct. The most important part of the
fit is your leg extension and knee position. As long as your seatpost extends high enough for proper leg extension and your saddle position and arm reach places your knee plumb with the pedal axle at 3 & 9 position you should be alright. If your stretched out reaching for the bars your going to have back problems. If you are sitting too far foward and your knee is forward of your pedal then your going to have serious knee problems. My suggestion is to fit the bike to your torso and legs first, then adjust for reach. If you don't trust your LBS go to a different shop or google "bike fit". Good luck. -Michael |
#3
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
RP10128 wrote:
I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? No, a short stem makes for a bike that doesn't handle as well as it should. The primary measurement for a bike *is* the top tube. A taller seat post can make up for the frame size otherwise. Also, as you get more fit and in better condition, you will have a tendency to want to get *longer*, that is be more stretched out. How did you arrive at the 50.5 dimension for the top tube? |
#4
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
"Dave Thompson" wrote in
: RP10128 wrote: I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? No, a short stem makes for a bike that doesn't handle as well as it should. The primary measurement for a bike *is* the top tube. A taller seat post can make up for the frame size otherwise. Also, as you get more fit and in better condition, you will have a tendency to want to get *longer*, that is be more stretched out. How did you arrive at the 50.5 dimension for the top tube? In two ways. First, I have been riding my current bike (a 52 cm. Trek) with the saddle slid all the way forward, and with the nut that secures the seat post clamp slid all the way forward. With the saddle in that position, the distance from the mid point of the saddle to the center of the head tube is about 50 cm. Second, I feel that the top tube of my current bike (which has a top tube of 52.3 cm.) is about 2 cm. too long. |
#5
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
"tntcoach" wrote in
oups.com: I would say the LBS is mostly correct. The most important part of the fit is your leg extension and knee position. As long as your seatpost extends high enough for proper leg extension and your saddle position and arm reach places your knee plumb with the pedal axle at 3 & 9 position you should be alright. If your stretched out reaching for the bars your going to have back problems. If you are sitting too far foward and your knee is forward of your pedal then your going to have serious knee problems. My suggestion is to fit the bike to your torso and legs first, then adjust for reach. If you don't trust your LBS go to a different shop or google "bike fit". Good luck. -Michael You suggest that I fit the bike to my torso and legs first, and then adjust for reach. But do you mean that I should get the smaller frame with the shorter top tube, or buy the larger frame and then install a very short stem? |
#6
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
RP10128 wrote:
I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? Where it comes to fit, the only thing that matters is the relative position of three points... 1) Saddle 2) Crank 3) Bars Now obviously, it's possible to get the above items right without having a bike that's a joy to ride (think "really, really long stem"). In your case, if you can get the three "fit points" right with a stem that's no longer than 10-11cm at the most, INCLUDING getting the bar HEIGHT right, then you should be pretty good to go. The only real down side to riding a "shorter" (vertically) frame is that the bar height RANGE is lower. If you don't need the bars up around the level of the seat and/or can live with lots o' spacers and/or a stem with considerable rise, the "shorter" frame should work. A tool to help you work out the stem issue: http://www.habcycles.com/fitting.html Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $795 ti frame |
#7
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
RP10128 wrote in news:Xns96A0D45BAB0C5richardpu2aolcom@
216.196.97.131: I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Top tube is more important, but if your seattube is too small then (depending on frame geometry), your head tube may be very low. If you want your handlebars several inches below saddle height, that may not be a problem. If you want a more upright riding position, then you may have fit or handling issues. |
#8
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
RP10128 wrote:
I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? Mark Hickey had some good advice above, but I just wanted to add that seat tube angle can also vary between frames, and it's good to consider this in addition to the top tube length. A 50.5cm top tube on a frame with a 74 degree ST angle is not quite the same as one with a 73 degree ST angle. If you put your seat in the same position relative to the bottom bracket on both, then the reach to the bars will be about 1 cm longer on the 74 degree frame (since you will need to slide the seat farther back on the rails to get it in the same position). Anyway, it's a very good idea to get properly fitted... there are lots of online calculators and articles, and/or you could get it done at a shop. I just noticed that the price of a Habanero went up $100! Hasn't it been $695 since the beginning? Maybe the recent currency value changes in China had something to do with this... -Ron |
#9
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
"RP10128" wrote in message 31... I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? Keep in mind that the smaller the frame, the lower the handlebars will be. For example, you probably wouldn't be able to get them anywhere near saddle level, because the saddle will be that much higher in relation to the frame. Pete |
#10
|
|||
|
|||
Correct Top Tube vs. Correct Frame Size
RP10128 wrote: I need a bike with a top tube of about 50.5 cm. To get a top tube of that length, I need to get a frame that is one or two sizes too small. That is, I would have to get a 49 cm. frame, whereas my inseam would indicate a 52 cm. frame. My LBS says that it doesn't matter that the frame is so small, but this strikes me as being counter-intuitive. Is the LBS right? Should I get the correct size frame and install a very short stem? Problem with a too small frame is the head tube is short and then the hbars will be very low. To raise to a ridable height, need a lots of rise stem or lots of spacers under the stem or something. Frames from different makers are all different. perhaps a custom? http://www.waterfordbikes.com RS-14 series is only custom, made to order. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Autofaq now on faster server | Simon Brooke | UK | 216 | April 1st 05 10:09 AM |
Rec.Bicycles Frequently Asked Questions Posting Part 1/5 | Mike Iglesias | General | 4 | October 29th 04 07:11 AM |
what size is my frame tube? (for upgrading derailleur) | tsp | General | 2 | October 1st 03 01:25 AM |
Threaded versus threadless headset | Hjalmar Duklęt | General | 64 | August 29th 03 06:55 PM |
Warning - Mikado (ProCycle, Canada) Frame Fiasco (IMO Bad design) | mark freedman | General | 8 | July 18th 03 07:37 PM |