Sizing a bike correctly -- woman 5'9" with long legs

[manzanita6]

Hey, I have a very heavy mountain bike but am looking to buy a used road bike or very lightweight hybrid, hoping to get my speed up a little on longer rides. (Not racing speeds, just up to 14-15 MPH instead of 12-13). My question is: what size bike to buy (in cm and in inches)? I'm 5'9", with pubic bone height about 35" (if I measured right). Also very long arms. I prefer a more upright ride if possible, and a positioning that's easier on my back/knees, if that's the kind of thing that positioning affects. (I dunno these things!). I know it's dependent on a lot of factors, but can anybody put me in the ballpark? Thanks very much!! Sarah PS: One more question: does my having especially long arms and legs tend to make me need a larger size than an ordinary person my height? Or does it just mean I'll likely have to adjust more?

 

[Dave Cutter]

Originally Posted by manzanita6 .

does my having especially long arms and legs tend to make me need a larger size than an ordinary person my height? Or does it just mean I'll likely have to adjust more?

An inseam length (as measured for slacks) of 34 inches would very typical for a 5' 9" woman (of your height). I am NOT calling you "ordinary" but you are well within standard for women. Often tall... or women with long legs... reach their height at a young age and can feel disproportionate. But trust me... you're normal.

You could easily stand over the top tube of a very large bicycle. But stand-over height is only one measure of fit and in the case of people (of both sexes) with long legs not the only consideration. The reach to and height/position of the handlebars is a consideration as well. Shop around the various bicycle shops... try out a few bicycles. Talk to the people working in the bicycle shops and other female cyclists as well.

 

[Dr Lodge]

Originally Posted by manzanita6 .

Hey,
My question is: what size bike to buy (in cm and in inches)?
I'm 5'9", with pubic bone height about 35" (if I measured right). Also very long arms. I prefer a more upright ride if possible, and a positioning that's easier on my back/knees, if that's the kind of thing that positioning affects. (I dunno these things!).
I know it's dependent on a lot of factors, but can anybody put me in the ballpark?
Thanks very much!!
Sarah
PS: One more question: does my having especially long arms and legs tend to make me need a larger size than an ordinary person my height? Or does it just mean I'll likely have to adjust more?

I'm a bloke around 5'9", with proportionally longer legs than arms. Frame sizes vary widely since the standard measure of bottom bracket centre to top of top tube, isn't meaningful due to the varying amount the top tube slopes.

On my standard "old" geometry bike that has a level top tube, I have a 22" seat tube with 21" top tube. On my new bike the seat tube is 54cm with 54.5cm top tube, and the top tube slopes down 4cm in height - so in theory that means its a 58cm frame!

My advice is to try some bikes to get a fit that feels right, and see what the EFFECTIVE TOP TUBE length is, and what length stem it has. Those combined give your critical dimension. Your chosen frame should conform to that spec (top tube may be 1 or 2 cm out with a change in stem length but I would suggest an optimum stem length is 10-12cm. I have a 12cm stem.

FWIW, Cannondale frames have moderate angles so see if you can try one of these out for starters e.g.

 

[alfeng]

Originally Posted by manzanita6 .

I have a very heavy mountain bike but am looking to buy a used road bike or very lightweight hybrid, hoping to get my speed up a little on longer rides. (Not racing speeds, just up to 14-15 MPH instead of 12-13).

My question is: what size bike to buy (in cm and in inches)?

WHAT is the EFFECTIVE TOP TUBE LENGTH on your MTB's frame?

Are YOU comfortable on it?

What is the effective stem length?

What is the differential between the handlebars AND the top of your bike's saddle?

Is your MTB a Hardtail OR does it have a Full Suspension?

Did you want your new bike to have DROP handlebars OR do you prefer FLAT handlebars?

FYI. There is probably no reason why you probably couldn't simply retrofit your current frame with 700c wheels + a Road crankset:

​

The CF Road + Drop bars & Road shifters would be "optional" for YOU ...

If your MTB has a suspension fork, then replacing it with ANY Rigid fork will probably reduce the weight of your bike by a couple of pounds.

Minimum tinkering is required to use 700c wheels with most MTB frames.

BTW. The above bike has an aluminum frame & the pictured weight is just under 20 lbs.

It could be made slightly lighter with some higher end components ...

A steel framed MTB Hardtail with the same components would weight a couple of pounds more.

A Carbon Fibre Hardtail frame equipped with the same components would weigh about a pound less.

 

[oldbobcat]

Generally, a combination of long legs, long arms, and good posture is an indication to size up a bit, but not too much. Long legs require more height, but short torso length indicates a shorter top tube. On the other hand, having long arms allows you to reach a little farther out and lower to the handlebar, and good posture allows you to cover the top tube more effectively. With 35" legs you could easily straddle an extra large hybrid like a Trek FX in 22.5", but the top tube and handlebar would be a stretch. If your legs were more average, a 17" WSD (women's) or 17.5" unisex would be right for your torso, but you'd be reaching too low for the handlebar, and it might even be a bit too close in.

Not a big problem, though. Split the difference and try a 19" WSD or 20" unisex. Your long arms should be able to reach the handlebar without throwing the upper body off balance, and if it isn't quite right it can be easily corrected with a shorter or taller handlebar stem. If you go for the unisex frame, ask the dealer about a narrower handlebar. It isn't difficult to saw off a a couple centimeters after you've bought the bike. Also, don't hesitate to ask the dealer to try a slightly more set back saddle position to move your center of gravity away from your arms.

I have somewhat similar proportions, and this is is how I've been fitting my bikes since the 70s.

 

[el gato]

competitivecyclist.com has a Fit Calculator which I found helpful when I was looking to purchase a bike recently.

 

[swampy1970]

If you're comfy on your mountain bike you could always just fit some better tires that may be more suited to riding on the road than standard mountain bike tires.




I've not used those Continental tires but I have similar on an old mountain bike and they ride so much better than knobblies on the road. Much cheaper than a new bike too

 

[manzanita6]

You guys are really all spectacular. Thanks for the great advice.

I've been swamped with work the past few days and have yet to read through all the comments carefully, and will respond in more detail when I do.

Wanted to add in the meantime that my current bike does seem relatively comfy, but one thing I noticed is that I seem to put too much weight on my wrists currently, and bend them too much while riding.

Seems like a Very Bad Thing when it comes to avoiding carpal tunnel and similar ailments--I know you're supposed to generally keep your wrists and hands aligned, not cram a bunch of weight down on the heel of your hand while your wrists are bent.

Perhaps this could be because my handlebars aren't high enough?

 

[danfoz]

re

Originally Posted by manzanita6 .


Wanted to add in the meantime that my current bike does seem relatively comfy, but one thing I noticed is that I seem to put too much weight on my wrists currently, and bend them too much while riding.

Seems like a Very Bad Thing when it comes to avoiding carpal tunnel and similar ailments--I know you're supposed to generally keep your wrists and hands aligned, not cram a bunch of weight down on the heel of your hand while your wrists are bent.

Perhaps this could be because my handlebars aren't high enough?

This may just be the orientation of the handlebars in the stem. i.e. you may have to extend excessively at the wrist (as opposed to flex the wrist) to comfortably manipulate the brake lever. If that is the case simply loosening the stem faceplate slighly and rotating the handlebar forward ever so slighly (could be just 2 or 3mm) such that the wrists are in a more neutral position, may help. It's the same thing that leads to carpal tunnel typing, reducing the amount of wrist extension usually remedies.

Being comfortable on the bike is often a result of evenly distributed weight. Any weight you take off the wrists will likely migrate directly to the saddle. There are a few things that can also falsly transalte into more weight on the wrists - a saddle that is tilted to far forward can cause the rider to slip toward the bars as they ride, forcing the rider to continually prop themselves back up, in addition a saddle that is too far forward placing the rider in front of the bottom bracket spindle (the bit that connects the 2 crankarms), while despite putting the rider closer to the handlebar can lead to a feeling of too much weight on the bars. You also may simply be too low and need to have the bar raised slightly. Someone knowledgeable at your local shop may be able to help. Without someone able to take an actual look at you on the bike, it's impossible to determine.

 

[Conniebiker]

I would say that the wrist tilt is more a function of brake lever position/tilt and how far your seat to bar relationship is. If it is long it will place more weight on the arms and result in eventual sag posture if you do not compensate(I do that too sometimes). Setting the brake levers a little lower than straight with the forearms can aleviate that, but don't go very far past it. BTW, I ride a 20" mtb with a stubby handlebar stem and seat slid 2/3 forward to compensate for legs about as long as yours. Out of all the variations I have tried, that has been the most comfortable for racing and long touring for 13 years. I tried a 17" mtb with a long stem a while back and I couldn't get it to feel right. Go fig.

 

[danfoz]

Originally Posted by Conniebiker .

Setting the brake levers a little lower than straight with the forearms can aleviate that, but don't go very far past it.

Yes. Aside from adjusting the levers separately, rotating the handlebars slightly in the stem is an easy way to make this adjustment.