# RS sizing question



## robpar (Jan 26, 2008)

Looking at RS but the LBS will not let me test ride until I pay a "fitting" fee for each bike a test ride (they will credit the fee to the purchase) but I don't think I will buy from this shop. The bad news is that there are no other Cervelo authorized dealers (hard to believe)
I was sized recently at another shop and I need: top tube: 558 mm; reach: 390 mm; stack from BB to CL of bar: 704 mm 
So I'm between a 54 and a 56. I currently ride a 580 mm top tube (giant TCR Composite) with a 90 mm stem simply because the larger frame had a taller head tube (180); my bars are about 1 cm below the seat; at times though, I feel a tad stretched out.

I'm 5' 9 3/4" tall; 34" inseam; 26.5" arms. I've also used some of the on-line fit calculators and they vary between 10 to 20 mm depending on the "fit". I don't race but like to go on long rides 3 or 4 times/week (30-40 miles) as fast as I can; I'm 55; fairly flexible and weigh 170.

So... I'm debating between a shorter top tube but longer steerer tube above the headset. BTW, how much steerer tube length is acceptable/safe for a 54 frame? OR longer top tube with taller headtube and less spacers.
Is it better to go for the larger frame (56) and taller head tube?
IS there a difference in handling or comfort?
I really like the look of Cervelos but maybe they are not a good fit for me. At the worst case I may choose a size (hopefully the right one) pay the fitting fee and ride it.
Any comments appreciated, Thanks!


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## capt_phun (Jun 14, 2004)

I think the headtube on the 54 is tall enough for you. The 56 would have a long TT& you'd have to run a stubby stem. FWIW, I would ride the 51 RS at 5'9".


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## jiggerjake (Oct 23, 2008)

*Frame size 6ft.w/36"inseam*

robpar,sorry to hijack your post.
What size frame would you guys recommend for someone 6ft.and a 36"inseam?All leg short torso/ avg.arms.
I've been watching e-bay and there are some good deals popping up on RS frames and complete bikes.
If I can buy the right size frame I plan to have a fitter help me out with the rest-stem,bars.stack ht.etc. Thanks


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## giro_man (Oct 29, 2003)

robpar, I don't understand why the fitter specified a top tube length when the stack and the reach are the critical measures. Aside from top tube, the data points you in the direction of a size 56 Cervelo. From your description, stack height is what caused you to buy the large-sized Giant. The size 56 Cervelo, at least in head tube size, is about the same as the large Giant which suggests a similar stack height. The size 56 Cervelo has an effective top tube measure that is shorter than your Giant which suggests that you could put a longer stem on the Cervelo.

If the store would allow you to put your large Giant side-by-side the 56 Cervelo for comparison, you might be able to judge whether the above assessment is correct.

To get the fit that you seem to desire, you need to keep the handlebars fairly high and the reach to be a bit shorter. A size 54 Cervelo may result in too much difference.


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## Comer (Jan 13, 2009)

I'm 5'11 with a 34 inch inseam and weigh 156lbs. I rode a 56cm RS with no spacers and a 110 stem.

I'm currently riding a 56 s3 with 2cm of spacers and a 110 stem.


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## jiggerjake (Oct 23, 2008)

Comer said:


> I'm 5'11 with a 34 inch inseam and weigh 156lbs. I rode a 56cm RS with no spacers and a 110 stem.
> 
> I'm currently riding a 56 s3 with 2cm of spacers and a 110 stem.


So with my being 6' w/36"inseam would I be better off on the 58 with a few spacers and shorter stem so as not to have the seat post as high as it would be on a 56,and still not be streched out?


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## robpar (Jan 26, 2008)

I appreciate your response. It seems to reinforce my intuition. The 54 frame will require an additional 20 mm of spacers to get the bars where I currently have them. Even though, it appears that the smaller frame (54) will give me more choices on stem length if I lower the bars while still maintaining the same overall reach. You bring up a good point regarding "stack" and "reach". This data is not readily available on a lot of frames. It seems TT, ST, , standover height, head angle and seat angle are the most common. 
I was also reading on Competitive Cycling's site that for long rides and comfort one should try the largest size that one can ride.
I will be trying the 56 inch for a fitting this weekend (I guess it's worth the money to avoid a silly mistake on an expensive frame)
Thanks!


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## Comer (Jan 13, 2009)

I had and have a pretty good size drop from my saddle to bar, at least 10cm maybe a bit more. My s3 with two spacers is the same drop as my RS with no spacers.

I'd say that with a 36 inch inseam you have to use spacers on the 56 or ride a 58. Do you like a lot of drop?


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## parker3375 (May 6, 2008)

*Maybe a little help*

I just ordered my cervelo the other day. According to my retul fit I should ride a 58cm cervelo. I'm 6' with an average to long inseam with shorter arms. So for the op I would recommend the 56 and for the other gentleman I say get the 58 and run a shorter stem. If you get a larger size with the correctly cut steerer then you can always drop a couple of spacers if you feel like it...since you can't add length to it. Just my 2 cents in the matter.


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## jiggerjake (Oct 23, 2008)

I really don't want a lot of drop.But I thought I would need the 56 for the reach factor.Would rather ride a 58 with shorter stem if you guys are thinking that would work better for me.I'm buying the RS for the more up-right geometry,so as long as I won't be too streched-out,the 58 may be the way to go.Thanks


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## lookrider (Dec 3, 2006)

To the OP. I'm almost the exact same height and inseam as you and I have lousy flexibility. You definitely want the 54. I test rode one today and I felt like I could have basically ridden with no spacers and the stem flipped down and comfortably ridden in the drops. I would probably keep 2cm of spacers and flip the stem and I could ride a century in the drops. The bike fit that well. I think the test bike had 2 to 3cm of spacers and the stem was turned up. My saddle height is 74 to 75cm. I felt like I was on a beach cruiser. That being said, it's an awesome bike.


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