|Bike fit question: 5'9" with really long 87cm legs||ahaile|
Jan 27, 2004 8:46 AM
|Hi All --
First off, thanks to all those who have offered advice about bike sizing on this forum. I've been trolling through the archives and there's a lot of really useful info here for a beginner like me. But I haven't found any posts that address my situation exactly.
Based on the measurements I've been taking of myself, I apparently have almost freakishly long legs and fairly long arms as well. Since my legs are so long, I assume my torso is short, but I don't know what the standard measure is for that. Here are my numbers:
Height: 175cm (just under 5' 9")
Inseam (hard contact barefoot): 87cm (34 1/4")
Normal saddle height: 77cm
Arm reach (tip to tip): 184cm
For the last four months, I've been riding a 56cm late '80s Bianchi, which I initally thought was the right size for me. But I've had to push the seatpost out to max extension to get the saddle high enough, and I've also had to use a mountainbike stem to get my bars high enough (saddle is 21cm over the top tube). So my sense is that 56cm is too small. But how much larger to go? If I get a larger frame, won't I then need a really short stem to make up for a longer top tube? Which is a better compromise, a tall stem on a smaller bike or a short stem on a bigger one?
If it matters, I usually ride about 2-3 20 mile rides during the week where I push hard, then one 30-60 mile ride on the weekend where I go at a more moderate pace. Also, I've never been very flexible and come about 3" short of touching my toes. Finally, I'm a starving grad student, so a custom frame is unfortunately not feasible. If there's any other information that would help, I'm happy to provide it.
Thanks so much for any and all advice!
|I'm in nearly the same boat,||cmgauch|
Jan 27, 2004 9:24 AM
|5'10" long legs/short torso, but my inseam is more like 33". I don't have too many complaints on off-the-shelf 56/57cm road bikes or 18/19" mtn bikes, but maybe I just don't know any better.
You may find this site helpful:
They have a pretty good sizing model there.
|not long legs...||C-40|
Jan 27, 2004 9:35 AM
|Your inseam and height are pretty average, not an example of long legs and short totrso. I would not expect a fit problem with off the shelf frames.|
|saddle may be too high....||C-40|
Jan 27, 2004 9:32 AM
|Your inseam is on the long side, but not outrageous. You're about 10cm taller than I am, with an inseam that's 4cm longer than mine.
Although your inseam is 4cm longer than mine, your posted saddle height is 6cm longer. If you use LOOK pedals and shoes that require an adapter, this could account for 1cm or more of the additional height. I use low stack height Speedplay pedals with Sidi shoes that require no cleat adapter. This can help to keep the required frame size smaller.
My rough guideline to setting saddle height is to be sure that you can drop our heel 3-4cm below horizontal with the leg locked out at the bottom of the stroke. This should create approximately a 15 degree angle between the upper and lower leg with the foot horizontal during normal pedaling.
Many people make the mistake of raising their saddle until their hips rock or they feel overextended and then reduce the height by a small amount. I made this mistake many years ago and have pictures of my 55cm Tommasini with the seatpost at the max. height line. I suspect that my current saddle height is at 2-3cm lower than that old position.
If you want accurate advice on frame size, post the current height from the floor to the top of your bars, or the desired saddle to bar top dimension. A frame that reduces the height of the saddle to 17-18cm above the top tube would be better. Whether this larger frame would casue a stem length problem depends on the geoemetry of your current bike compared to those now available and the stem length (and angle) that you now use. In general, TT length only increases about half as much as frame size. Do you know any of your frame's dimensions? TT length and seat tube angle are the critical dimensions.
Jan 27, 2004 9:45 AM
|I am with C-40 on the saddle height thing. I am just under 5'10" and my inseam is also 87. My saddle height should be 77 in theory but reality is more like 74.5. I'm just more comfortable there.|
|saddle may be too high....||ahaile|
Jan 27, 2004 12:22 PM
|Thanks, C-40, for the advice. I'll definitely try lowering the saddle and see how that feels. One reason it may be unusually high is that I have short Achilles tendons -- basically, I "walk on my toes" a lot. Always been that way since I was a kid, though back then my heel rarely touched the ground. My pedals might be another part. I'm currently using a mountain bike pedal, as I also mountain bike and use the same shoe for both. They're Crankbrother's pedals, and I see on their website that they have a 15mm stack height. Is that more than a road pedal? Do mtb shoes have thicker soles than road?
To be honest, I'm still experimenting with stem length and saddle to bar drop and I don't know exactly where I want them. The frame I've been riding is an '89 Bianchi Brava (I mentioned the starving graduate student part, right?). Here are the frame dimensions as I measure them:
Seat tube: 54cm c-c, 55 c-top of TT, 56 c-top of ST
ST angle: 74-73.5 (not exactly sure -- I measured it as 74, but I put it next to another bike whose published specs were 74 and mine looked ever so slightly more shallow, like 0.5cm at the top tube difference)
TT length: 55cm c-c
I started with a 110mm 90-degree stem that gave me 3" of drop from the saddle. This was comfortable for a while, but after riding a couple months and getting more comfortable bent over, I felt a little short horizontally. I know the handlbar-blocking-view-of-hub method of sizing is considered questionable, but FWIW, with the 110mm stem the hub was in front of the handlebar about 1.5cm in my line of sight. I then switched to a 130mm 80-degree stem. I liked the reach better, but the bar was too low, about 4" below the saddle, and my neck and shoulders would get sore after rides. I gave that six weeks to see if I would get used to it, and I did some, but I still think it's too low. Just this week I got a 130mm 95 degree stem, but the weather's been so bad I haven't been able to try it yet. It gives about 3" of drop and feels more comfortable sitting on the bike, but I won't know until I can ride it.
I'm not sure if the attached photo is useful or not. I took it about four months ago when I had just put the 110mm 90 degree stem on and wanted to see how my position looked. It was also before I moved my saddle back about 1cm to get better KOP. If it would be of use, I can get a picture of myself on the current setup tonight.
Thanks again for your advice.
|it does look a bit high...||C-40|
Jan 27, 2004 1:28 PM
|The picture does not show an extreme problem, with the heel raised high, but trying a lower position can't hurt.
Changing from a 110 to a 130 stem is big jump. If you are comfortable with such a long stem it would also make me suspect that the saddle may be too far forward. A saddle that's too far forward can place tooo much weight on the hands. Remember that KOP is just a starting point. I ride with my knee nearly 2cm further back, for example.
If you experiment with saddle fore/aft position, the saddle should be moved down by .3cm (1/8") for each cm that it is moved back.
|Hey, email me off the board...||MShaw|
Jan 27, 2004 5:28 PM
|I have something that may interest you...
mikeshawTWO@cox.net (but ya gotta replace the TWO with 2 to reply)
|Your inseam is the same as mine, and I'm on a 59cm||Kerry Irons|
Jan 27, 2004 5:15 PM
|My 59 cm Litespeed has the (standard) seat post nearly at the limit. I don't know the relative measurement methods of the Bianchi vs. LS, but it sure seems like your frame is too small.|
|Another photo, different bike||ahaile|
Jan 27, 2004 8:20 PM
|Thanks everyone, especially C-40, for all your advice. By the way, I went and remeasured my saddle height, and it's actually closer to 76cm now than 77. I swapped seats recently and apparently the new one is thinner top-to-bottom. Huh, maybe that's one of the reasons I seemed more comfortable on it!
I've attached another photo, though on a different bike. This is a frame I'm considering buying. Any comments on my position? The frame has a really good price on it, but I'm afraid that at 57.5 c-c ST, 58 c-c TT, 73* ST angle it might be too big on me. Because of the shallower ST angle, I get the same reach (55cm seat tip to bar) when I put a 110mm stem on this frame as my Bianchi with a 130mm. But if I scoot my seat back as C-40 suggests, I don't have far to go before I would need a really short stem. With my seat at 76cm, there's 16.7mm from the top tube to the seat, and the drop from saddle to bar is 6 cm. This photo is with cranks level. I'll follow with one showing cranks vertical. Thanks again for the great advice!
|Same bike, cranks vertical||ahaile|
Jan 27, 2004 8:21 PM
|Same, but with cranks vertical instead of horizontal|
|frame is too big...||C-40|
Jan 28, 2004 8:07 AM
|The reach looks about right, IF the saddle fore-aft position is correct, but the frame is too big vertically. The saddle is obviously low relative to the frame. Is the saddle pushed forward to achieve that reach? The saddle height may still be bit high. The leg angle isn't bad, but it looks like your heel may be raised up to achieve it.
I'd experiment with the other bike for while. If you're only 5'-9" tall, a 55cm TT should be pretty close, unless you need the saddle far forward. Try moving the saddle back and see what it feels like. I've moved mine back nearly 2cm this year in an effort to improve my climbing and it has not hurt my cadence, as long as I lower the saddle (.6cm) to keep my maximum leg extension the same.
|frame is too big...||ahaile|
Jan 28, 2004 9:56 AM
|Thanks again, C-40. Wherever you live, if I ever come through town I owe you a beer ... or a high-protein fruit smoothie or whatever you drink.
Yeah, I thought the frame might be too big. The saddle is all the way back but on a 0 setback (Thomson) post, so about equal to the middle of a normal post. I just tried dropping a plumb line and measured the tip of the saddle as about 7.5cm behind the BB, though that could be off by +- .5cm. I also tried dropping a plumb from my knee, but that's pretty hard and inaccurate to do solo. I think I'm about right at KOP, not behind, which means if I did go behind, the reach might get too long.
I also spent some time last night playing around with the "ergobike" fit system, and according to it, I have long femurs so probably need the seat further back than most.
Looking again at the pictures I posted, I realized that it's a little hard to see how high the seat is relative to the bike. The bike has an under-seat bag that looks like the back of the saddle in the photos. I've attached a little photo of just the bike so you can see better, but I think you're probably right that the saddle's still pretty low on the frame.
Thanks again. I think I'll try going back to my 110mm stem on my old Bianchi and setting the seat back and seeing how that feels.
Jan 28, 2004 11:28 AM
|My rule of thumb for a properly sized bike is to have the saddle 16-18cm above the top tube. 16cm is lower than I would use, but more than 18cm definitely points to a (vertically) too-small frame.
My saddle is about 17cm above the top tube and it yeilds about a 9cm drop from the saddle to the top of the bars using an 84 degree threadless stem with no spacers under it.