Help with frame sizing

[Darrenjs92ni]

I was looking at getting a "Jamis Trail X2 Bike 2009" to share temporary with my brother till I can decide on better bike. Any ways I was using the frame calculator on e bicycles and it recommends a frame size of 19" from Center of bb to Top of seat tube C-T.

Now if you look at the manufactures frame chart it has the 19" frame as having 15.47" center of bb to top of seat tube.

[attachment=1983]

The only bigger size is 21" but it only has a 17.35" center of bb to top of seat tube!

I’m really confused as to why it is 19" frame but only really has a 15 1/2" frame, is it because it is a Trail bike?

[JohnV]

The measurement you are looking at is from the center of the BB to the top of the Top Tube not the seat tube. You might want to start with looking at the stand-over measurement first. I'm not sure what the numbers mean, but on most road bikes you get them in small, med, large, etc. I would see if you can find a cross-reference chart to see exactly what size those frames are. Also, someone that knows the size chart would be able to help you in the sizing.....ROB are you there?

[Darrenjs92ni]

oo, i see i saw i was comparing the center of the BB to the top of the seat tube to center of the BB to the top of the Top Tube. But is the 19" on that chart the center of the BB to the top of the seat tube?

[JohnV]

No, its from the center of the bottom bracket to the top of the top tube at a 90 degree angle. Depending on the bike, the top of the seat tube can be from one inch to several inches above the top tube. If you have a photo of the bike (or better yet, the frame) from its side, you can calculate the distance from the center of the bb to the top of the seat tube by measuring the distance from the center of the BB to the top of the top tube.

Does this make sense, because there are way too many tubes here?

[Darrenjs92ni]

(03-07-2011, 02:45 PM)JohnV Wrote:  No, its from the center of the bottom bracket to the top of the top tube at a 90 degree angle. Depending on the bike, the top of the seat tube can be from one inch to several inches above the top tube. If you have a photo of the bike (or better yet, the frame) from its side, you can calculate the distance from the center of the bb to the top of the seat tube by measuring the distance from the center of the BB to the top of the top tube.

Does this make sense, because there are way too many tubes here?

Right i think i get it, so on the picture i have drawn its the purple line is the 17"!?!

[attachment=1993]

theres a link to the bike at the top of the page.

[JohnV]

That is correct.

[Darrenjs92ni]

(03-07-2011, 04:51 PM)JohnV Wrote:  That is correct.

Thank you

[taladega]

Hello, Just got a Jamis d29
I am 6.4 - 270 in weight.
They sold me a 19in, I now just discovered on what the bike shop said it was my fit.
My inseam is 34.5 / Extended arm reach 73in
In 3 outings and less than 6 hours ride time I have fallen numerous times even breaking a rib.
It seem that I have to set the seat very high, while the handlebars sit very low, thus throwing my weight forward.
All my prior bikes have been 21in or 22in.
I am a seasoned rider both in MTB and Road, and never ride above my limit, Nor have I fallen of the bike since a beginners 20 plus years ago.

Do you think I have he right bike?
Hope hope you can offer insight on body weight, height and sizing a rider.

Thanks
Love you website.

[RBurrelli]

You should contact the shop that sold it to you and discuss your problem. Fitting can be complicated, but I would venture to say that it sounds too small for you.

There are a few different versions of the D29 on the Jamis website. Looked at the geometry for the D29 Comp. Standover and wheelbase are the differences between the 19" and 21". but the measurements are not that different. You probably would have more control with the larger wheelbase.

[taladega]

Thank's
As picture, in "Red" Bike seat is very high, so I can ride with some leg room
While handlebar is very low. this is causing me to ride with all my weight forward.
Bike shop owner said, there is no way to bring the front upwards and
that who was going to buy the used bike?

On Facebook, others have said my body weight is more than this bike can handle and not to ride it ever again. Is this Accurate?
I don't think I will be riding for a while...

[RBurrelli]

It is usually common that you lower your seat when mountain biking. Provides better balance and leverage.

[taladega]

Thanks RBurrelli, I agree, been riding 20 plus years.
This image is "lower" on a 19 for me. anything less and my knee will see the sky...

I guess one should never go out and buy a bike on a days where the store is full of people.
Can't ride something that does not fit, what a rip off. Moreover my Ribs hurt.
Next eBay time...

[nfmisso]

I have had a similar experience with a poor fit from a LBS (Hyland on S Meridian in San Jose, CA); at least two size too small, and the shop had only one other customer, with a couple extra employees standing around.

Bottom line, if you want a good fit, know what you need before you go to the shop.