So daughter is looking to get a frame but falls between sizes …so is it better to go or down a size. The chart has her in two sizes, the smaller frame is 10 to 15 mm ish shorter than she is uses get, but the larger is 10 to 15 mm longer than usial. 29er wheels as well.

So which is best option and no she cannot try a frame to my knowledge.

When you say “10-15mm” shorter/longer, which measurement is that?

If it’s effective top tube, try comparing reach/stack of her current frame with the new one.

Either way, that sort of amount is easily accommodated by slightly altering stem length and saddle fore/aft. Personally I go smaller, as I prefer more stand-over, assuming the seatpost doesn’t end up silly long.

Sorry to effective….stack and reach is proving more variable…..

I’d go longer, unless it’s a BMX then nothing much gets better on small frames apart from standover, and that’s only a problem if you stop and stand over the bike (bikes are for riding, not stopping).

Are we talking daughter still growing (in which case it’s obvious which to go for) or grown up daughter? And what sort of frame? Even the XC bikes these days are growing 15-25mm longer than a couple of years ago (and stems dropping from 110 down to 90mm), but you do need a slacker (~69) head angle to make that work.

bikes are for riding, not stopping

Brilliant…! 8)

She is early twenties so I think stop growing…..

I don’t disagree that more standover is often better, just that it’s a very odd place to start at when picking a bike. If you’re a nervous rider and want more standover, then limit your choice a frame designs with a lot of standover. But picking a frame size too small to improve it at the expense of having to squeeze into a frame too small and compromise handling seems counter productive.

Calculate her ape index….. Worked for me

Help

Go larger. Current geometry frames won’t benefit from adding long stems or masses of seat layback to get the fit right.

Depends on the frame though.

why dont you buy a different bike with more appropriate geometry? with all the different brands one will be ‘right’. right being subjective, of course, based on personal preference.

If it’s a mountain bike or hybrid i.e. not drop bars, sounds like the way forward is the larger frame, you could always swap the bars for something with a bigger rise/sweep to get the reach corrected.

Road or mtb? For road, I would always suggest the smaller frame. Stems can be easily swapped for reach. Bikes with longer stems and shorter top tubes handle better as there is more weight over the front wheel. For mtb, I prefer a longer frame and shorter stem. Stand-over is probably a bigger factor though.

MTB….
And 29er which can feel bigger at times….??

Depends what kind of bike I’d say. And perhaps choose a different bike with different lengths to suit better.

My Patriot is on the small size for me, my El Mar is on the large side, but that suits each bike and the associated riding style perfectly.

Having bought my first bike too small I’d say larger if you are between sizes. With subsequent bikes I had demos and/or I asked the manufacturer but this included letting them know stem size I’d be using. If you are buying off the shelf complete bike have a look at stem length as you can chnage that longer/shorter also saddle can move forward/back on its rails.

On paper I was between sizes for my latest bike. Bought the Large and it felt a touch too big. Paid postage and exchanged for a medium and feels spot on.

So the reach and stack is mm
Reach 421.3
Stack 623 .7
ETT 600
Classed as medium

This compares to
Turner sultan large
R – 414
S _ 627
ETT 599

Yeti sb95
R 434.4
S 632
ETT 612

Santa Cruz highball
R 418
S 626.1
ETT 609

So how come so much variation Iarge to medium and

Still struggling as she likes the Yeti sizing but also had a sultan which she loved…..

I’d always say if you are between sizes, go large

I’ve found that having gone for a medium frame, when I could have gone large (according to maunfacturers details), large should have been picked.. 🙄

If she want’s to run a dropper I’d also consider the difference in seat tube. I’m boarder line S/M on most frames. I went with a small (Anthem) as the extra 50mm on the seat tube would have been problematic with a dropper. As it is the small is set up with a 70mm stem to give me the same position as a 55mm on my small (15.5″) prince albert. I think it was the right choice for me. I’m avoiding trying a medium now in case it isn’t 😉