A remarkably elementary question about frame size

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wafter

I like steel bikes and I cannot lie..
Location
Oxford
lol at post #6 - I must admit the OP was slow going and I didn't get much from it, but I just assumed this was the result of my apparently ongoing thickening..


As has already been touched upon, within the realms of most rider sizes wheel size is irrelevant to bike fit.

My advice would be:

Find a spacious corner with a flat, horizontal floor and clear, vertical wall. Once you’ve spent an hour facing inward in silence in repentance for the quality of your OP, swap places with one of the bike – nosing the front tyre hard up against one wall and leaning the bike against the other whilst keeping it as vertical as possible, and the front wheel straight. You might need to bodge something to hold it in place.

Using a tape, measure horizontally from the wall to the centre of the BB, and from wall to the top of the head tube (top face on centreline of tube). Subtract the second dim from the first for your reach.

Do the same in the vertical axis to the floor; from the BB and the head tube again – subtract the first from the second to get your stack.

Now you have industry-standard values that allow you to compare your bike frames to any other.

While you’re at it you can repeat reach and stack measurements for other key bits – namely the stem clamp axis and contact points on the bars (centre of the grips on flats; tops, hood and drops on drop bars).

Obviously you understand how the shape and size of stems and bars will impact the location of contact points relative to the fixed point at the top of the headset, and how these can be manipulated to aid fit.

The above process will give you a sound, quantitative grounding to understand and compare the fit of your existing bikes. If you have a favourite bike for fit, it will help you replicate this on the others.

The relativity between drops and flats can be a bit nebulous – for example wider bars will make a given reach feel longer because as your hand span widens the effective length of your arms along the bike shortens.

There’s doubtless a large amount of subjectivity in there too with regard to how aggressive people want their position.

With respect to your drop bar bike; the first part of fit should always be saddle position. I like the “straight leg with heel on pedal” method for height. Fore-aft is more nebulous and I find best reached through ride feel.

Then setup the front end. It sounds like it’s too long and low; so options (other than another frame) are a taller quill stem with less reach, and / or more compact bars as those look to have quite a lot of reach and drop. These are things that can be measured in isolation and compared to values given by more reputable bar manufacturers.

My old Giant was a bit like this – longish reach (390mm) and low stack (545mm) with long stem (125mm) and massive bars (160mm drop, 110mm reach) – for an entry-level bike it was really aggressive. I was getting horrible headaches / neck pain and eventually swapped the stem for an inverted 100mm item and bars for some with 125mm drop and 75mm reach.

This made the setup a lot less aggressive and far, far nicer to ride.


So yeah, I’d suggest you measure your own bikes and compare the dims for that which fits best to the available frames you have, and what you could realistically achieve with them through the use of different bars and stems :smile:
 

Punkawallah

Veteran
Hi Andy. Perverse curiosity obliges me to ask -why- you think your current bike is ‘too small’?
 
OP
OP
Andy in Germany

Andy in Germany

Legendary Member
Hi Andy. Perverse curiosity obliges me to ask -why- you think your current bike is ‘too small’?

A number of somewhat subjective factors; I'm in uncharted territory here: I got through life assuming "mind your head" signs are for other people, but it "feels" small.

After riding the bikes above, the Wayfarer (drop bar tourer) feels a bit "cramped": In order to have the straight leg position or thereabouts I have to raise the saddle quite high, and I noticed this sometimes causes discomfort and/or numbness in my hands, which can be resolved by raising the bars, although the quill is a bit short, so I can't do it much. The saddle on my Brompton feels higher in relation to the pedals.

At the same time the reach feels short: I deliberately got a stem with minimal forward reach because I thought I'd be stretched, but the opposite has happened. These two factors can make the bike feel "strange" at the start of a ride; it doesn't generally bother me after that, but I notice I don't have as much push on the pedals as I do with the longtail.

I know its probably irrelevant but the high saddle and stem on the small frame looks odd to me. I find aesthetics important in a bike, or to put it another way, I'm fussy. (Personal appearance not so much, you'll notice there are no pictures of me on this forum)

Someone up thread suggested the handlebars may be too large: I've thought that myself and "acquired" a couple of bars with smaller drops from the scrap pile at work so that may be an option.

I'd assumed that the larger wheels would result in a better proportioned frame, both physically and aesthetically. I noticed that 28" wheeled bikes do feel slightly more comfortable, and I seem to ride them a bit faster, although that could be half a dozen factors not related to wheel size: I ride a lot of different bikes, so I can't be sure.

Also, the factor that my Daughter has her eye on the red bike, and I'm itching to build another project is also probably at play here...
 
OP
OP
Andy in Germany

Andy in Germany

Legendary Member
lol at post #6 - I must admit the OP was slow going and I didn't get much from it, but I just assumed this was the result of my apparently ongoing thickening..


As has already been touched upon, within the realms of most rider sizes wheel size is irrelevant to bike fit.

My advice would be:

Find a spacious corner with a flat, horizontal floor and clear, vertical wall. Once you’ve spent an hour facing inward in silence in repentance for the quality of your OP, swap places with one of the bike – nosing the front tyre hard up against one wall and leaning the bike against the other whilst keeping it as vertical as possible, and the front wheel straight. You might need to bodge something to hold it in place.

Using a tape, measure horizontally from the wall to the centre of the BB, and from wall to the top of the head tube (top face on centreline of tube). Subtract the second dim from the first for your reach.

Do the same in the vertical axis to the floor; from the BB and the head tube again – subtract the first from the second to get your stack.

Now you have industry-standard values that allow you to compare your bike frames to any other.

While you’re at it you can repeat reach and stack measurements for other key bits – namely the stem clamp axis and contact points on the bars (centre of the grips on flats; tops, hood and drops on drop bars).

Obviously you understand how the shape and size of stems and bars will impact the location of contact points relative to the fixed point at the top of the headset, and how these can be manipulated to aid fit.

The above process will give you a sound, quantitative grounding to understand and compare the fit of your existing bikes. If you have a favourite bike for fit, it will help you replicate this on the others.

The relativity between drops and flats can be a bit nebulous – for example wider bars will make a given reach feel longer because as your hand span widens the effective length of your arms along the bike shortens.

There’s doubtless a large amount of subjectivity in there too with regard to how aggressive people want their position.

With respect to your drop bar bike; the first part of fit should always be saddle position. I like the “straight leg with heel on pedal” method for height. Fore-aft is more nebulous and I find best reached through ride feel.

Then setup the front end. It sounds like it’s too long and low; so options (other than another frame) are a taller quill stem with less reach, and / or more compact bars as those look to have quite a lot of reach and drop. These are things that can be measured in isolation and compared to values given by more reputable bar manufacturers.

My old Giant was a bit like this – longish reach (390mm) and low stack (545mm) with long stem (125mm) and massive bars (160mm drop, 110mm reach) – for an entry-level bike it was really aggressive. I was getting horrible headaches / neck pain and eventually swapped the stem for an inverted 100mm item and bars for some with 125mm drop and 75mm reach.

This made the setup a lot less aggressive and far, far nicer to ride.


So yeah, I’d suggest you measure your own bikes and compare the dims for that which fits best to the available frames you have, and what you could realistically achieve with them through the use of different bars and stems :smile:

Lots of very useful information there, thank you. I will now go and look for a corner to stand in...
 
OP
OP
Andy in Germany

Andy in Germany

Legendary Member
Then setup the front end. It sounds like it’s too long and low; so options (other than another frame) are a taller quill stem with less reach, and / or more compact bars as those look to have quite a lot of reach and drop. These are things that can be measured in isolation and compared to values given by more reputable bar manufacturers.

I knew someone had mentioned this; I think the drops are a little oversized; they were a scrap pair I happened to have lying around.
 
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