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Discussion Starter · #1 · (Edited)
Bike Fit: 54 or 56 cm frame?

I rode last year on a 56 cm cannondale with a 100 mm stem and the seat moved pretty much all the way forward. I'm 5'10" with a 80.8 cm inseam. I paid for a fitting at one of Boston's best bike shops.

Measuring myself tonight (probably not too reliable) for the Flyte system I get 66 cm for torso length, and an arm extension of 64 cm. By this system I should get a bike that is 54.1 cm (they don't say which measurement this is) with a 115 mm stem. This is pretty close to what I have now. When I go into random bike shops and get the casual eyeball method size recommendations from the workers they always say I could go with either a 56 or 54. Here are pictures of me and the bike: http://www.garyjaz.com/r700/index_r700.html

I was bothered by my stem size when I started racing. It seems most racers are using 110 or 120 cm stems, so I started thinking my bike was too big for me. The 56 cm Cannondales have a top tube length of 56 cm, and the 54 cm bikes have a top tube length of 54.5. [ Cannondale geometry here: http://www.cannondale.com/bikes/06/geo-613.html ]

It's time to order a new bike and I'm wondering if I should get the smaller bike and put on a longer stem. It's only 15 mm shorter and this could easily be made up with a longer stem and moving the seat back some.

Isn't it better to have a bike that is a tad small rather than too big for racing crits and shorter road races? I think I became comfortable being stretched on the bike and my coach thinks I should get more aero. Putting a longer stem on my 56cm could do this, but the seat is still very forward (KOPS appropriate). To get more aero on the 54 would mean getting a longer stem and moving the seat back some, and I'm not sure if this would change the muscle groups I use adversely or give me more power. Do you lose power if your seat is too far forward?

I got to ride a 54 cm Six13 for a week and it felt alright, but it was hardly a controlled experiment as just about everything was different about this bike compared to my R700. The stem was 110 mm, and overall it felt smaller.

What would you do? I'm sticking with Cannondale as we get deals on them. I have till Friday to get my team order in....

-g

*I would get the 55 cm bike but cannondale only offers this size in their very expensive team ones this year. I have searched for an older aluminum 55 all winter to no avail.
 

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You could call Flyte...

GaryJaz said:
I rode last year on a 56 cm cannondale with a 100 mm stem and the seat moved pretty much all the way forward. I'm 5'10" with a 80.8 cm inseam. I paid for a fitting at Boston's best bike shop.

Measuring myself tonight (probably not too reliable) for the Flyte system I get 66 cm for torso length, and an arm extension of 64 cm. By this system I should get a bike that is 54.1 cm (but they don't tell me which measurement this is).

I was bothered by my stem size. It seems most racers are using 110 or 120 cm stems, so I have been thinking I should get a smaller frame. The 56 cm Cannondales have a top tube length of 56 cm, and the 54 cm bikes have a top tube length of 54.5.

It's time to order a new bike and I'm wondering if I should get the smaller bike and put on a longer stem. It's only 15 mm shorter. I would get the 55 cm bike but cannondale only offers this size in their very expensive team ones this year. I have searched for an older aluminum 55 all winter to no avail.

I only started biking last year but I got very serious and intend to race quite a bit this year. Isn't it better to have a bike that is a tad small rather than too big? I think I became more comfortable as I rode last year (more stretched I guess) and my coach thinks I should get more aero. Putting a longer stem on my 56cm could do this I guess, but the seat is still very forward (KOPS appropriate).

What would you do? I have till Friday to get my team order in....


They all ride and would advise you on their bikes.
 

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gastarbeiter
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I have a 12 year old c'dale 2.8 (which was a team bike - i'd never pay for a c'dale, at least 12 years ago).

i'm 5'9", and have an 80 cm inseam, with gorilla arms. i have a 54, with a 120 stem, which is more than fine. a 15cm stem sounds way too long, even if you are an inch taller than me.

GaryJaz said:
I rode last year on a 56 cm cannondale with a 100 mm stem and the seat moved pretty much all the way forward. I'm 5'10" with a 80.8 cm inseam. I paid for a fitting at one of Boston's best bike shops.

Measuring myself tonight (probably not too reliable) for the Flyte system I get 66 cm for torso length, and an arm extension of 64 cm. By this system I should get a bike that is 54.1 cm (they don't say which measurement this is) with a 15 cm stem. This is pretty close to what I have now. When I go into random bike shops and get the casual eyeball method size recommendations from the workers they always say I could go with either a 56 or 54.

I was bothered by my stem size when I started racing. It seems most racers are using 110 or 120 cm stems, so I started thinking my bike was too big for me. The 56 cm Cannondales have a top tube length of 56 cm, and the 54 cm bikes have a top tube length of 54.5. [ Cannondale geometry here: http://www.cannondale.com/bikes/06/geo-613.html ]

It's time to order a new bike and I'm wondering if I should get the smaller bike and put on a longer stem. It's only 15 mm shorter and this could easily be made up with a longer stem and moving the seat back some.

Isn't it better to have a bike that is a tad small rather than too big for racing crits and shorter road races? I think I became comfortable being stretched on the bike and my coach thinks I should get more aero. Putting a longer stem on my 56cm could do this, but the seat is still very forward (KOPS appropriate). To get more aero on the 54 would mean getting a longer stem and moving the seat back some, and I'm not sure if this would change the muscle groups I use adversely or give me more power. Do you lose power if your seat is too far forward?

I got to ride a 54 cm Six13 for a week and it felt alright, but it was hardly a controlled experiment as just about everything was different about this bike compared to my R700. The stem was 110 mm, and overall it felt smaller.

What would you do? I'm sticking with Cannondale as we get deals on them. I have till Friday to get my team order in....

-g

*I would get the 55 cm bike but cannondale only offers this size in their very expensive team ones this year. I have searched for an older aluminum 55 all winter to no avail.
 

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not enough info...

You have provided very little info to go by, other than a 100mm stem with the saddle moved "pretty much all the way forward". That doesn't tell us much, because seatposts vary greatly in setback from zero for a Thomson straight-up post to 3.5cm for an FSA K-force.

You don't mention your saddle height, or your saddle to handlebar height difference. The smaller frame will have a 2cm shorter head tube, requiring either 2cm more spacer under the stem or about 12 degrees more stem rise.

I also get the impression that you're not aware that saddle fore/aft movement is supposed to be used to change the knee to pedal relationship, not the reach to the handlebars. Also keep in mind that frame size has nothing to do with saddle position, it's the seat tube angle that's important. In the case of these two frames, the STA of the 54cm is .5 degree steeper which reduces the TT length difference to only 1cm, instead of 1.5cm.

It seems like the 54cm would be the better choice, but only if it does not require a wacky stem and spacer setup.

To evaluate your current setup, see if you have knee to arm interference while pedaling with your hands in the drops, your fingers in reach of the brake levers and the uppper back as low as you would use for aggressive cornering. If there's interference, it means you have a conservative setup for a crit racer.

As for the saddle fore/aft position, a further forward postion will generally promote a higher cadence, lower torque application of power, with the reverse being true for a further back position. Neither is guaranteed to produce more or less power. Since power = torque x cadence, both have equal value in the equation. Optimum power production is a balancing act that must also take endurance into account.
 

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i'm also 5'-10"
riding a 56 always feels a bit big and clunky for me. I've got pretty good flexibility so that might help but i ride a 53 for my race bike. Its a Masi which run a longer top tube so it rides more like a 54. It feels great. Older steel lugged frames seem to fit a little better running larger so i might consider a 56 if that was the type of bike i was looking at. But i'd be weary. I've had some fitters that really balked at fitting me on a 56. If you have a long torso and upper body (compared to normal) perhaps its the best fit. Otherwise go 54
 

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C-40's response seems the most informed.

I'm also 5'10". I don't know my cycling inseam, though I wear 31 inch pants. I ride a 56 cm Cannondale and considered a 58, but I liked how the smaller frame fit me better. If you've tested the 54 and don't like it, why not get another 56.

And if you get good deals on the Cannondale, if it doesn't fit right, you can probably sell it used for about what you paid and then just get another one that fits better.
 

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Discussion Starter · #7 ·
botto said:
I have a 12 year old c'dale 2.8 (which was a team bike - i'd never pay for a c'dale, at least 12 years ago).

i'm 5'9", and have an 80 cm inseam, with gorilla arms. i have a 54, with a 120 stem, which is more than fine. a 15cm stem sounds way too long, even if you are an inch taller than me.

My bad: I meant 115 mm.
 

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Discussion Starter · #8 ·
Thanks for this response C-40. The drop from my seat to handlebars is about 4 cm. When I got it I had all 5 spacers beneath the stem, but I've moved the bars down so that three spacers are on top of the stem, and I reversed the angle (6 degrees). I'm not sure about the seat post; it's the stock one called "cannondale carbon".

I have no interference when I'm in the drops, even though I'm all bundled up in winter layers.

Would a picture help?


C-40 said:
You have provided very little info to go by, other than a 100mm stem with the saddle moved "pretty much all the way forward". That doesn't tell us much, because seatposts vary greatly in setback from zero for a Thomson straight-up post to 3.5cm for an FSA K-force.

You don't mention your saddle height, or your saddle to handlebar height difference. The smaller frame will have a 2cm shorter head tube, requiring either 2cm more spacer under the stem or about 12 degrees more stem rise.

I also get the impression that you're not aware that saddle fore/aft movement is supposed to be used to change the knee to pedal relationship, not the reach to the handlebars. Also keep in mind that frame size has nothing to do with saddle position, it's the seat tube angle that's important. In the case of these two frames, the STA of the 54cm is .5 degree steeper which reduces the TT length difference to only 1cm, instead of 1.5cm.

It seems like the 54cm would be the better choice, but only if it does not require a wacky stem and spacer setup.

To evaluate your current setup, see if you have knee to arm interference while pedaling with your hands in the drops, your fingers in reach of the brake levers and the uppper back as low as you would use for aggressive cornering. If there's interference, it means you have a conservative setup for a crit racer.

As for the saddle fore/aft position, a further forward postion will generally promote a higher cadence, lower torque application of power, with the reverse being true for a further back position. Neither is guaranteed to produce more or less power. Since power = torque x cadence, both have equal value in the equation. Optimum power production is a balancing act that must also take endurance into account.
 

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very conservative...

If you've only got a 4cm height difference between the bars and saddle, your positon is both very conservative and definitely not suited for the smaller frame. If you can work your way up to an 8-9cm height difference, the smaller frame might be considered.

For example, if you can ride the 56cm with NO spacers under a -6 (84) degree stem, then the smaller frame should be considered.
 

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smaller bikes w/ longer stems look a ton cooler than biger bikes w/ short stems IMHO. Also, if you're into being cranked over in a quite aero position, smaller frames are better too (i.e. about every pro cyclist's bike)
 

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Discussion Starter · #11 ·
C-40 said:
If you've only got a 4cm height difference between the bars and saddle, your positon is both very conservative and definitely not suited for the smaller frame. If you can work your way up to an 8-9cm height difference, the smaller frame might be considered.

For example, if you can ride the 56cm with NO spacers under a -6 (84) degree stem, then the smaller frame should be considered.

I plan on getting the bars lower with time.

Here are pictures of the me w/the bike: http://www.garyjaz.com/r700/index_r700.html

What do you think?
 

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not bad....

Your position doesn't look too bad to me. Since you have knee to arm clearance with only a 100mm stem, it means a shorter TT would work fine.

If you can get to the point that you can tolerate a lower bar height, then the smaller frame would be OK. With lower bars, you won't need very much bend in your arms to get into the same position in the drops.

With the samller frame, you'd need one size longer stem with the same total length of head tube and spacers used on the larger frame. To insure an accurate changeover, the saddle height and distance from the tip of the saddle to the BB center should be set first. Then a duplicate a diagonal measurement from the tip of the saddle to the center of the bars (assuming the saddle model is not changed).
 

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Discussion Starter · #13 ·
Thanks again C. So are you saying that I would be better off on the 54cm bike?

I should point out that the coach of our team had me get on his 56cm cannondale with a 120mm stem and the seat set all the way back (stock R5000). The seat height was just a little too high. He's almost 2 inches taller than me, yet he thinks the 56 is the way to go. I could put a smaller stem and move the seat forward some. He's a Cat 1 racer and has way more experience than anyone else I know, but it seems if he's that much taller and has a 56, I should go smaller. Maybe I should fork over the dough for a 55cm Team 1 and be done with it.


C-40 said:
Your position doesn't look too bad to me. Since you have knee to arm clearance with only a 100mm stem, it means a shorter TT would work fine.

If you can get to the point that you can tolerate a lower bar height, then the smaller frame would be OK. With lower bars, you won't need very much bend in your arms to get into the same position in the drops.

With the samller frame, you'd need one size longer stem with the same total length of head tube and spacers used on the larger frame. To insure an accurate changeover, the saddle height and distance from the tip of the saddle to the BB center should be set first. Then a duplicate a diagonal measurement from the tip of the saddle to the center of the bars (assuming the saddle model is not changed).
 

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Go Aggies
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Sizing is a goofy thing. I was sized for a 56 (I'm 5'11") then my coach (who does bike fits for a living) set me up with a 90mm stem and said I need a smaller bike next time I go shoping. To me You look streched and would like the 54 better. Go and test ride the 52 54 56 58 (I'm not joking) to feel the true differences in the sizes. Good Luck

Garrett
 

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maybe...

A 1cm change in frame size is pretty insignificant. I'd go by the amount of stem spacer required to produce the bar height you need. You're not down all the way on the 56cm and there's always an 80 degree stem to further lower the bars.

You can make a 54 or 56 fit exactly the same. The biggest difference would be in the weight balance. The shorter front-center will put more weight on the front of the 54.

Looking at the picture, are you comfortable in the drops? Your wrists look bent at an awkward angle. With the bars rotated up like they are, the drop section is more vertical than normal. Finding the perfect handlebar shape can be tough. A bar like the Deda 215 will bring the brake hoods up without rotating the bars, but you may find the drop section too short. You should also consider the reach of your handlebars. The old Easton EC-90 carbon bars were one of my favorites, with more room in the drops and no need to rotate the bars upward.

I'm thinking of trying the new EC-90 Equipe (not the Equipe Pro), $200 is an expensive experiment. The EA-70 would be a lot cheaper. It has a shorter reach, which would require a longer stem than the EC-90.

http://www.eastonbike.com/PRODUCTS/BARS/bar_road_ec90_equipe.html
 

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Discussion Starter · #16 · (Edited)
Yes,that's what I figure, the center of gravity will move closer to the front of the bike. This will make it seem harder to brake, I imagine. When I tried the 54cm the steering seemed twitchy too. But I'm sure I'd get used to this. What are the advantages of having the weight shifted toward the front?

As for the handlebars, I just turned the stem over a couple of weeks ago and have been meaning to adjust the handlebars so that they fall forward a little bit more. If I turn them down, won't my arms be even straighter when on the hoods?

Funny you should mention the Equipe EC90, since this seems to me to be the best value in handlebars and it's what I intend to put on my new bike. I wasn't aware they had carbon versions.

Interesting idea about the handlebar-seat heights. I can still drop 2 more of those spacers (look to be about 5mm. ?), and as you point out, a different stem could bring it down maybe another cm. 6-7 cm drop seems enough for an old guy like me. That would be 6-7cm lower than I raced all of last year, and I did quite well. Still, my coach says I should aim for 4 inches. That's 10 cm! He's only 3 years younger than me, so I guess it's possible.

Oh, he pointed out that in my pictures you can see the tip of the seat, meaning I could move it back some.....

BTW, the STA is the same for the 54 and 56.




C-40 said:
A 1cm change in frame size is pretty insignificant. I'd go by the amount of stem spacer required to produce the bar height you need. You're not down all the way on the 56cm and there's always an 80 degree stem to further lower the bars.

You can make a 54 or 56 fit exactly the same. The biggest difference would be in the weight balance. The shorter front-center will put more weight on the front of the 54.

Looking at the picture, are you comfortable in the drops? Your wrists look bent at an awkward angle. With the bars rotated up like they are, the drop section is more vertical than normal. Finding the perfect handlebar shape can be tough. A bar like the Deda 215 will bring the brake hoods up without rotating the bars, but you may find the drop section too short. You should also consider the reach of your handlebars. The old Easton EC-90 carbon bars were one of my favorites, with more room in the drops and no need to rotate the bars upward.

I'm thinking of trying the new EC-90 Equipe (not the Equipe Pro), $200 is an expensive experiment. The EA-70 would be a lot cheaper. It has a shorter reach, which would require a longer stem than the EC-90.

http://www.eastonbike.com/PRODUCTS/BARS/bar_road_ec90_equipe.html
 

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rotating the bars...

Rotating the bars down will increase the reach to the brake hoods and decrease the reach in the drops. I always set the angle of the drop section first, then postion the brake/shift levers to a comfortable angle. Another thing to keep in mind is that when you flipped the stem you increased the reach of the stem by one size in addition to lowering the bars. That's a big change to make all at once.

Keep working on the stem height. I'm 52 and manage to use a 9cm drop on a 51cm frame. I've tried 10cm and felt OK on the brake hoods, but on long mountain descents, my neck didn't like the extreme angle required to look down the road.

I'm not sure why your coach wants you to move the saddle back. You look pretty well stretched out to me and you say your knee is directly over the pedal. I've used a 2-3cm further back position for climbing, but found little advantage. More torque can be applied to the pedals with the saddle further back, but that's no guarantee that more power will be produced, since power = torque x cadence. You'll spin faster with the knee no more than 1cm behind the pedal spindle and the bike will corner better with more weight on the front. You might not notice the improved handling, except in the most extreme cornering. I do a lot of extreme cornering while descending the winding mountain roads. Never had the chance to do that before moving to Colorado.
 

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I'm 5'10" and rode a 54cm Caad5 for a couple of years...the fit was perfect!
Now I ride a medium cinelli that has a 54.5cm TT, and on both bikes I had a 120mm stem.
 

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Discussion Starter · #19 ·
Perfect, 853. Just what I want to hear tonight as I put in an order for a 54 cm R5000. What a relief to be done with this! And as he was punching in the order he asked if I wanted the compact SLK or not and I chose the compact for the heck of it. Never tried one before. I've got a Dura Ace 53/39 that I'm going to put in this bike when I get it, but now I'll have a tough hill race option.

Thank you all for your advice. It made a difference.

-gary


853 said:
I'm 5'10" and rode a 54cm Caad5 for a couple of years...the fit was perfect!
Now I ride a medium cinelli that has a 54.5cm TT, and on both bikes I had a 120mm stem.
 

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consider test riding the cannondale that comes with the SRM power meter in the 54 and 56cm configurations. whichever bike gives you the deepest tuck with maximal power is probably the size to go with.
 
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