Smaller bikes: where do things start to go wrong?

[Mitford]

I'm 5 foot 6 with a 30 inch inside leg. I went to a bike shop yesterday and they suggested a 52 cm road bike, after sitting me on a Specialised Allez that size. I've been riding a 56 cm road bike and that is too big, i.e. the seat has to be set too low and I think I have to stretch too far forward.

I've been thinking that instead of getting a bike made to measure, I might get a Surly Pacer, it seems to be what I am looking for, a fairly restrained traditional-looking thing, in steel, with reasonably good and modern equipment.

I'm pondering whether I should go for the 52 cm model, or maybe go a size smaller, 50 cm. I've done a bit of reading, and discovered that as bikes get smaller you can run into difficulties with the geometry, so causing handling problems, maybe toe overlap. I'm wondering at what stage these problems kick in. Is a 50 cm bike more of a problem than a 52 cm model? The figures for the geometry of the Pacer in these two sizes are here: http://surlybikes.com/bikes/pacer

I am considering the smaller model because 1. I like small, neat things generally. 2. It might look better with the seat high. 3. The reach will be smaller.

Can anybody point out the problems I might run into by taking the smaller size bike, regarding both the geometry of the bike and how it might fit me?

 

[Dan B]

Toe overlap may or may not be a problem depending on how much slow-speed riding you do - is this a town bike for filtering through congested traffic or a long-rides-in-the country bike. Also consider that your front mudguard, if you have one, will be increasing the effective size of the front wheel

 

[alicat]

There is no substitute for trying a bike before you buy. If you do have to buy sight unseen it is easier to adapt a smaller bike and add a longer stem than shrink a bike that is too big. You could compare the dimensions of the Allez with the Surly and see which of the two Surly models is the closer in size.

You may get toe-overlap with the larger size depending on how big your feet are. This doesn't bother me so long as I am aware of it when turning in tight circles. It does however bother other people.

 

[youngoldbloke]

Generally no problems - I ride a 44cm Ribble (sloping top tube = 50 cm horizontal), a 52 cm Ribble winter bike, and a 21" steel. Can't say I have noticed any untoward effects. Maybe small bikes begin to look a bit ill proportioned, but you can also get smaller framed bikes with 650 wheels - probably not necessary at 5'6" (I'm 5'5", and shrinking ).

 

[Mitford]

is this a town bike for filtering through congested traffic or a long-rides-in-the country bike. Also consider that your front mudguard, if you have one, will be increasing the effective size of the front wheel

Thanks Dan, I'm very much in the long-rides-in-the-country category, can't remember the last time I filtered. I'm also a no-mudguards man.

Thanks Youngoldbloke: "Maybe small bikes begin to look a bit ill proportioned".

There's a photo of a 50 cm Pacer here, what do you think, does that look well-proportioned to you?

http://www.flickr.com/photos/circles-jp/5979875697/

Looks ok to me, but maybe that's just because it's my size.

Alicat: did you mean "with the smaller size"?

 

[youngoldbloke]

That Pacer looks absolutely fine to me - maybe bikes begin to look a bit strange when the frame gets much smaller - my 44cm has no gap between the down tube and top tube at their junction with the head tube - they touch, for example, and with a sloping top tube the seat tube begins to be rather short, so that the wheels begin to look a bit big for the frame - often most noticeable on smaller size womens-specific bikes.
I forgot one problem - with smaller frames you may need to use side entry bottle cages - with my sloping frame there is just not enough room within the frame triangle to pull a bottle out of a 'normal' cage. Fine on the 52cm frame however

 

[accountantpete]

You could always check to see if the smaller bike has a slightly shallower angled headtube.

In the "old" days there was a lot of talk about wheelbase and it was common to see headtubes pointing a bit more in front of the bike to present the front wheel further forwards (and of course avoiding toe overlap).

Have a check to see if any modern framebuilders have remembered this.

 

[Mitford]

You could always check to see if the smaller bike has a slightly shallower angled headtube.

Hi Pete,

The head tube angle is 72 for the 50 cm bike and 72.5 for the 52 cm version. The bikes go down to 42 cm, with a 71 degree head tube angle and up to 62 cm 74 degrees. That seems like a steeper head tube on the smaller bikes.

The seat tube angle goes the other way: 75.5 deg for the 42 cm bike, 72.5 for the 62 cm.

 

[accountantpete]

Hi Pete,

The head tube angle is 72 for the 50 cm bike and 72.5 for the 52 cm version. The bikes go down to 42 cm, with a 71 degree head tube angle and up to 62 cm 74 degrees. That seems like a steeper head tube on the smaller bikes.

The seat tube angle goes the other way: 75.5 deg for the 42 cm bike, 72.5 for the 62 cm.

By shallower I meant that the angle was reduced for smaller bikes so that smaller bike 72deg big bike 74deg.

Here's a Canondale ladies bike with a slightly more pronounced example

 

[alicat]

No - I meant the larger size ie you might opt for that and still find you get toe overlap.

 

[Shut Up Legs]

Try to get a test ride of a bike of the brand, model and size that you want, even if it means visiting various bike shops around your region before going back to your preferred shop and giving them your business. You can measure and plan all you want, but a test ride will give you a much better idea.

I did this when buying my new road bike in November, taking a bike from LBS A for a test ride, but then buying a different model bike at LBS B. Given that I shop occasionally for parts at LBS A (mainly for things I need quickly, or things it's inconvenient to buy online), I think they're not unhappy with me for not buying the bike there. I'm still on good terms with them .

 

[Mr Haematocrit]

I'm 5 foot 6 with a 30 inch inside leg. I went to a bike shop yesterday and they suggested a 52 cm road bike.

I'm pondering whether I should go for the 52 cm model, or maybe go a size smaller, 50 cm.

I am considering the smaller model because 1. I like small, neat things generally. 2. It might look better with the seat high. 3. The reach will be smaller.

Can anybody point out the problems I might run into by taking the smaller size bike, regarding both the geometry of the bike and how it might fit me?

Your the same height as myself with the same inside leg, my Venge and Tarmac are both 52's with 90 mm stem and they are perfect for me.
A 50 just feels plainly wrong, I just can't get the size to feel right... If in doubt get a bike fit.

 

[RWright]

I am very close to 5' 10" with a 30 inch inside leg. I am riding 56 frames. I lost some weight and am becoming more comfortable (I have more to lose too), I also did some stem height and length adjustments. I would like to try shorter crank length as well. I have 170s now but would really like to try some shorter ones just to see how they feel. I have a feeling I would like 165's, maybe even 160s.

 

[Mitford]

Your the same height as myself with the same inside leg, my Venge and Tarmac are both 52's with 90 mm stem and they are perfect for me.
A 50 just feels plainly wrong, I just can't get the size to feel right... If in doubt get a bike fit.

I haven't found any Surly dealers in this area so I can't just go and try one. I went to a LBS and sat on some bikes yesterday.

I gave the whole thing a lot of thought last night, and I had a sudden flash of insight. At least I think that's what it was.

I made a silly mistake in my initial post. The road bike I have had for the last few years is not 56 cm it's a 52, with a horizontal top bar. There is only about 6 cm of seat post exposed, which is aesthetically displeasing, and it feels like a little too much stretch to the bars. So that must mean, if I get a 50 cm road bike like the Pacer, which has a relatively "relaxed" geometry, there will be a little more seat post exposure (plus the top tube slopes slightly on that size bike), and the reach will be a little shorter, which is what I want to achieve.

Any objections?

 

[Mr Haematocrit]

I would not worry to much about aesthetics, I would take a comfortable bike and one which I can enjoy over a thing of beauty any day.
I would most certainly spend some time with your LBS as they should be able to advise regarding fit and test ride some bikes.
I can't say I have a vast amount of seat post showing on any of my bikes, its never ever been an issue for me.