Bike sizing - how to spot too small a bike

bflk

I've asked to see the 52cm Emonda from the bike shop as that's the frame size of my current (non-Trek) bike, even though the official Trek guide says I should be on the 54. Doesn't sound like the shop are going to let me view both sizes side by side...

So I looked up the full geometry and got out my ruler and found the following - 52, 54 and 56cm frames with my bike in brackets. I've highlighted the best match with bold.

Seat tube: 49.3, 50.6, 53.3 (51.5)
Top tube: 53.4, 54.3, 56.0 (53.0)
Standover: 72.9, 74.2, 76.7 (76.2)

possibly minor value:
Seat tube length: 14.0, 15.5, 17.0 (15.0)

Saw a guy on ebay selling his 52 saying it would fit a 5-5 to 5-8 guy, I'm about 5-8/5-9 but I think my inside leg is slightly short for my height.

My question is, what obvious signs are there sitting on a bike that is too small?

To my uninitiated eyes it looks like the 52 is ok length/arm stretch wise but possibly not so good on height.

There is a 30 day return guarantee if I decide the first choice is wrong. The conditions for a test ride are very onerous and the shop is smack in the city centre and poorly suited for one anyway, unless I want to see how comfy it is sitting at traffic lights

kajjal

I also have a long body which for cycling is not a big issue, long legs and a short body can cause a lot of challenges fitting a bike. The height / size charts are just a guide, if you are between two sizes try both to see.

Roughly speaking for a road bike if you have loads of seat post showing, the front end feels way too low and you feel a bit crunched up then the bike is likely too small for you. If it is only a little too small it can be easily adjusted by flipping the stem upright and other changes. Part of your riding position is down to your body and part personal preference.

When test riding use the bars, the hoods and the drops to make sure all feel OK. Don't be rushed or pressured, and you should get a feel for the bike after a few minutes and adjust the saddle etc. to get a better fit.


Remember you after a bike that fits you well and makes you want to ride it. Some people like a head down stretched out racing position and others a more upright relaxed position.

svetty

I find head tube length is the limiter - unless you are flexible in the lower back and hamstrings dept a low front end will render a bike uncomfortable. Stack and reach are the parameters you really need to consider not tube lengths.....

grahamcp

If you can, find the stack and reach measurements of each bike and compare those. As far as I can tell the Edmonda 52 vs 54 is only a couple of mm different in reach, with greater difference in stack.

bflk

I got the Trek data for them too but they seemed a bit more fiddly for me to measure on mine which is why I just did the tubes...
From what I could make out the reach is a subset of the top tube provided the seat tube angles match? (which I guess they may well not).

I'm crossing fingers the predicted thunderstorms hold off as I gather they don't allow test rides if its wet

cougie

Don't stick with the trek then. Try other shops that will let you sit on both sizes.

gweeds

If a shop have both sizes and won’t actually let you compare them side by side then ask the manager WTF they’re playing at before taking your money somewhere else.

Matthewfalle

Gweeds wrote:

If a shop have both sizes and won’t actually let you compare them side by side then ask the manager WTF they’re playing at before taking your money somewhere else.

This

Its a Trek - you can get them anywhere and everywhere.

Go somewhere else with your hard earned that will let you try both bikes, perhaps throw in a pre sale bike fit that will be refunded to you once you have bought a bike from them and treat you like an adult.

bflk

I'm curious though how easy it is to find a bike shop with multiple sizes of each model in stock?

We have two vendors in town. One (A) had only a 56 in stock and flatly told me there was no way he would get either in just for me to try it for size.

The other (B), who I'm going with, didn't have any size in the shop but got in a 52 for me to try. They didn't offer to get BOTh a 52 and a 54 in at the same time which obviously would have been the ideal.

What I ended up was going to A and sitting on a 54cm SL6 Pro, the next one up from the one I'm after. That confirmed my suspicion it was a tad large. Then I popped around the corner and sat on the 52 shop B had got in for me. That seemed like a decent fit so I'm going for that one.

It may be that I'm a bit late in the season, certainly two models I'd been looking at have completely gone out of stock nationwide/regionally. It just so happend I got a windfall that arrived at the end of one of the warmest Mays ever and everyone else has gone bike purchase mad. It does strike me as odd to be looking at a bike shop website in May and seeing 2018 models labelled out of stock!