How can I find the right size road bike without a test ride?

Question

I am going to buy a road bike. I am considering a Trek 1.2.

I used the Competitive Cyclist Fit Calculator to find the size of bike that fits me.

Inseam:             80.5  
Trunk:              59.5  
Forearm:            36  
Arm:                67.2  
Thigh:              57.4  
Lower Leg:          53.7  
Sternal Notch:     138.1  
Total Body Height: 171

All the measurements are in cm.

The ranges that are given in the results are these:

Seat tube range c-c:   52.1 - 52.6 for competitive fit.  
Seat tube range c-c:   53.3 - 53.8 for eddy fit. 

The purpose of my bike is going to be able to do long distance mainly. I cannot afford another bike for racing but I will most probably be doing Ironman from next year using the same bike. But I personally think that riding 180 km in 8 hr is endurance and not year.

Now which size should I go for? 52 or 54?
Should I just check the standover height of the bike? Or I should I look into something more than that?

I am asking this because in India not many shops deal with Trek road bikes. The Trek 1.2 is only available at one shop. That fellow says he won't allow me to test ride the bike. So I am in a bad situation. I want to buy this bike but the right size. The whole geometry is available in the site I have given. Ask for more information, if needed.

Answer 1

I think you could ride either size comfortably. You may need to change the stem to accommodate your longer reach, but the range of adjustment for the seat is what you want to look at, not so much the seat tube length. When you look at sizing, the reach is as important as the height. But good fit can be achieved within a range of values; I think it is better to think of proper fit as a range of values rather than a point estimate.

You can obviously change the reach by changing the stem.

I faced a similar problem as you. My current main ride was an eBay purchase. It has the same sloping top-tube (TT) design as the one you are looking at. The nominal size is very different than my other road bike, so I used the CC Fit Computer to help me decide if the bike would fit, and 5,400 miles later I can tell you it fits very well.

The geometry of the Trek 1.2 is here; the geometry of my bike is here.

Just for the sake of comparison, my CC Fit measurements/results are:

Measurements

Inseam: 85.1
Trunk: 67.3
Forearm: 33
Arm: 61.6
Thigh: 59.7
Lower Leg: 57.8
Sternal Notch: 143.5
Total Body Height: 175.3

The Competitive Fit (cm)

Seat tube range c-c: 55.1 - 55.6
Seat tube range c-t: 56.8 - 57.3
Top tube length: 54.6 - 55.0
Stem Length: 11.2 - 11.8
BB-Saddle Position: 80.6 - 82.6
Saddle-Handlebar: 52.4 - 53.0
Saddle Setback: 4.0 - 4.4

The Eddy Fit (cm)

Seat tube range c-c: 56.3 - 56.8
Seat tube range c-t: 58.0 - 58.5
Top tube length: 54.6 - 55.0
Stem Length: 10.1 - 10.7
BB-Saddle Position: 79.8 - 81.8
Saddle-Handlebar: 53.2 - 53.8
Saddle Setback: 5.2 - 5.6

The French Fit (cm)

Seat tube range c-c: 58.0 - 58.5
Seat tube range c-t: 59.7 - 60.2
Top tube length: 55.8 - 56.2
Stem Length: 10.3 - 10.9
BB-Saddle Position: 78.1 - 80.1
Saddle-Handlebar: 54.9 - 55.5
Saddle Setback: 4.7 - 5.1

Your measurements show that you have a longer reach than I have, but shorter legs.

My bike is a nominal 53 cm (refer to the sizing chart) but the virtual frame size (the size if the TT was level) is a 56. I have it set up right now with the saddle at 70cm above the center of the BB and the reach set at 62 cm.

As for you, because your arms are longer, I think you would probably like the 54 better, but I do believe you could ride the 52 comfortably, perhaps with a slightly longer stem. My guess would be that the stock stem is 100mm.

Answer 2

It seems odd that somebody wanting to sell a bike to you wouldn't allow a test ride. Most places encourage you to take the bike for a test ride, at least around the parking lot or around the block, and usually with a bike store employee following closely behind. If they can't offer you a test ride, perhaps you could persuade them to mount the bike onto a trainer. That would at least give you some sense of how the bike fits, although doesn't tell you much about how it handles. Another option is to find a bike rental service that has the same model bike that you are planning to buy (some rental services even sell their old bikes). This can give you the opportunity to try out the bike for an extended period. If you still can't get a test ride, I'd opt for a different bike from a different shop that does allow test rides. There's nothing particularly special about the Trek 1.2 that you can't find in 100 other bike models, which are available in lots of different stores. I wouldn't recommend buying a bike without actually riding it first.

Answer 3

Buying a bike without riding it is a terrible idea. Similarly terrible ideas would include ordering a mattress without laying on it, laying down cash for a guitar without playing it, and purchasing bike shorts without trying them on. And I agree that any shop that won't let you test ride a bike is pretty suspicious. I'd try to take my business elsewhere.

That said, we live in a non-ideal world. Sometimes the perfect deal comes along, or you just plain need something and have to take a chance and buy it sight-unseen. In this answer, I'm assuming that you've tried to find other ways of riding the bike (asked friends, looked for other shops, etc.) and have failed to get that test ride.

There are ways to make an imperfect frame fit, if the sizing isn't too far off. Extra-long stems and seatposts, barends, saddle rail extenders... all of these are gadgets that you can buy to help get yourself on an ill-fitting bike. If you make some good guesses, yu can avoid using any of these contraptions.

What can you do to mitigate the risks?

First off, I'd read up on bike fit as much as possible. This way, you can make guesses that are informed guesses.

With any frame, even a custom-built one, you'll end up adjusting saddle-to-pedal distance, reach, handlebar height, and frame size. It sounds like you've narrowed things down to a couple of sizes; that's great, as it makes your job much easier.

Narrowing it down

In the two sizes you've chosen, which one will allow you more latitude when dialing in your fit?

If, for example, the smaller frame barely has enough standover height, that's a point in favor of avoiding the larger one. If the smaller frame would need an extraordinarily long stem to get a good reach (that's the saddle-to-handlebar dimension), that's a point in favor of the larger frame.

And so on. Tally up all of these factors and see which frame makes the most sense.

Can this possibly work?

Speaking as someone who owns a built-to-order road bike, who put money down before the thing was even built: It's possible to do this if you know what you want and know what's important to you.

An awful lot can go wrong. You've made a lot of guesses, based on your experience with other bikes, reading spec sheets, and just plain hoping your gut feelings are right. If you can't afford to los the money you'd spend on this bike, I'd think twice before ordering.

If it's possible to wait a while and test-ride a bike then (maybe you're going on vacation later this year and can hit some shops then?) (is a road tide coming to town? Put out a classified ad) I'd do that.

But if not, try to ride some other road bikes and get a good idea what's important to you in road bike fit. Remember that you're gambling a bit with your money, make the best guesses you can, and hope. The worst-case here is that you end up selling the bike and taking a loss.

Answer 4

I would advice to visit your Local Bike Shop (LBS) and try out ideally both bikes in both sizes. But at least try a bike in each size; and/or discuss with the LBS and have him measure your inseam and see what he says.

Answer 5

I remember one of the old Discovery Channel team mechanics, said the difference between Trek sizes isn't that big (2 cm) so their riders could use 1 size smaller or bigger. Other than fit, there's also personal preference, like going smaller to get a lighter frame, and pros do this.

So, don't sweat about it too much. If you have a pretty good guess about your perfect size, than 1 size smaller or bigger wouldn't matter much. Even if you did a test ride, I doubt that it will help much if you didn't have a good idea of what to expect. Even if you could get a perfect size (53 cm), because it's only based on seat tube length, it might not give you the perfect fit still because the top tube length could be shorter/longer for you.

You can adjust differences in seat tube length by adjusting seat post and switch stems to accommodate top tube length. I used to ride 52 and now riding 50 madone because the 52 was sold out and that 50 was heavily discounted. The shop shown me that even with smaller frame the measurements are still the same as the old bike.

That said, if you're thinking about ironman, I think you should go with the 54 because the the wheelbase is longer and will give more stability. Usually TT bikes have longer wheelbase.

Answer 6

The simplest correct answer is that without a test ride, you can't guarantee the correct fit. That is why test rides exist.

Either bike may be within the correct range, but you dont know which is better, until you ride them, and no one can tell you which is better, when you are looking at 2 bikes that are both in the right range.

It is a subjective decision, based on how the bikes feel to you.

Denying you a test ride is denying you the ability to get the right bike, guaranteed.

I know you want a different answer, but you need to look at a shop which will let you ride the bikes, even if it means going with a different brand or model.