road bike sizing

[dave123456]

5 11 with a 34" inside leg, what size would people recommend? understand the concept of trying before buying but after 25 years on a mountain bike I fear the 'right' size might feel odd on a short test ride...

thanks

[nammynake]

Frame size is largely determined by your reach. If your reach (arms/torso) is normal for your height then a 56 top tube should be about right. However, your legs seem quite long for your height, meaning your saddle will be quite high hence a large saddle-to-bar drop, unless you have lots of spacers / positive rise stem / long head tube. If you're flexible a large saddle to bar drop is fine, but most people won't have enough flexibility, which only leads to back/neck ache.

Plenty of shops offer a bike fit - this is a specific measurement of your body which will allow them to pick a suitable frame geometry for your body.

[dave123456]

I think my leg to torso ratio is high, so usually have a smaller mountain bike. Is there anyway round the saddle to bar drop issue?

[nammynake]

Yes, as I mentioned...stem spacers, stem with large rise angle and/or frame with a long head-tube (sportive geometry they call it I think).

As I said, get a decent bike fitter and he'll be able to recommend frames to suit. This may mean going with brands you're less familiar with, but I'd rather have a bike which fit me than one with the best logos.

[anonymous-user]

It really depends what you want. The Stack divided by Reach method is quite good, a figure of 1.4 puts you in a fairly racey position and 1.50 is quite upright. All the brands will have geometry data online, it sounds like you want a more upright bike but there are more variables to consider such as headtube height, look for bikes around 170-190mm...

[dave123456]

pablo said:

It really depends what you want. The Stack divided by Reach method is quite good, a figure of 1.4 puts you in a fairly racey position and 1.50 is quite upright. All the brands will have geometry data online, it sounds like you want a more upright bike but there are more variables to consider such as headtube height, look for bikes around 170-190mm...

thank you, although I may need a little more explanation...

[j00pY]

I would just chime in and say a deal where you can get a bike fit and a new bike would be ideal. For my height a 56 or 58 was recommended. It turns out that a 54 is actually what I need.

[anonymous-user]

Most road bikes these days have a sloping top tube, as a MTBer you will be familiar with this. Traditionally they had a horizontal top tube. Stack is the distance from the centre of the bottom bracket to the top of the head tube. Reach is the distance from that point to the centre of the head tube as below. This gives you a reasonably good indication of how you will fit on the bike and your position. It basically means that you can decipher the various sizing measurements the manufacturers use to describe their bikes.



some good sources of info here:
General: https://www.lfgss.com/conversations/248406/
A bit more detail: http://fitwerx.com/stack-and-reach

[scherzkeks]

dave123456 said:

5 11 with a 34" inside leg, what size would people recommend? understand the concept of trying before buying but after 25 years on a mountain bike I fear the 'right' size might feel odd on a short test ride...

thanks

55-56 c-t seat tube , if buying a newer bike with horizontal top tube. Otherwise look for a sloper with a top tube of about 55 cm. This should give you about 7-8 cm of drop on proper stage geo, which is normal assuming you are reasonably fit. Stem: 11 cm.

[outnumbered]

+1 on getting properly measured, if you're planning to spend anything above entry level. The fitter can assess your size, flexibility and the sort of riding you plan to do, and take all that into account.

I got a proper fit a few years ago, and what it told me was that I'd been riding the wrong size frame, in the wrong position for the last 15 years... I'm so much more comfortable, and actually a bit faster, with the revised position, even though it's actually more upright.