Frame sizing - Rules ???

[neilll]

what is the horizontal top tube length of a 16.5 Merlin and what is the maximum length of stem you'd be happy with.

A 16.5" Merlin has a 22.38" top tube, 16.75" chain stays, 29.2" standover, 11.7" BB height, 4" head tube and a 71 degree head angle.

I don't like stems over 140mm really.

Do you reckon that would be too small for me?

 

[cherrybomb]

I'm 5'8" and 16" is fine for me. A long seat post makes up for a short seat tube.

Oh dear...this is heading into $$$$ territory as I know where there is a 16.5" Merlin (I've been thinking it would be too small for me.....)

I think it probably would be a touch on the small size. Sounds as if we're about the same 'dimensions' and a 16.5" would be just too small for me. :cry:

You're still at it though - I thought you established, rightly, that the 'size' numbers are almost meaningless, unless you know how they are used by the particular manufacturer in question.

Before you can conclude that that 16.5 is too small, you need to know on what basis do Merlin measure it, what is the horizontal top tube length of a 16.5 Merlin and what is the maximum length of stem you'd be happy with. There's other things as well, but that's the minimum.

[just as an example BITD a size 17 Marin was far bigger than a size 19 Orange]

You're right. (and wrong) I thought Merlins had less of a sloping top tube than that, hence thinking a 16.5" would be small. I wasn't just judging by seat tube length..

If that top tube length is correct neill, then that sounds like a good size.

Srry mate, less of an excuse to hang on to your money. :roll:

 

[OrangeRetro]

Unfortunetly I would have to agree, that top tube length sounds good.. bad luck matey, sounds like your wallet is about to become lighter..

 

[orange71]

Well from the evidence presented you are at the extreme end of things, but that said the Ti bike does look quite ok

yes - that one along with my RSP fits me about right, but I still think the wheels look too small henc the 29er option.

 

[neilll]

If that top tube length is correct neill, then that sounds like a good size.

Yeah it's correct for an XLM...the 17.5" is only slightly longer with a top tube of 23.00"

I DO need to be a good boy though.....in the middle of buying a house at the mo.....

 

[Anthony]

A 16.5" Merlin has a 22.38" top tube, 16.75" chain stays, 29.2" standover, 11.7" BB height, 4" head tube and a 71 degree head angle.
I don't like stems over 140mm really.
Do you reckon that would be too small for me?

Well, that's for you to say, you know what you like, I don't, but certainly your willingness to use such a long stem makes it possible for you to be comfortable on a fairly small frame. With a 140 stem, that 16.25 frame is going to be much the same length as a size 20 with a 90 stem.

Basically it's just a matter of what is your ideal distance between the bb and the top of the saddle and what is your ideal length from the saddle to the bars. The height of the bars is also a factor, but more easily adjusted with spacers and riser stem/bars. Obviously somebody with very long legs couldn't use a very small frame because he wouldn't be able to find a seatpost long enough to get the saddle up to the right height. And somebody with a long torso who doesn't like the steering with long stems is going to need a long top tube. etc

 

[andrewl]

The same factor may explain why AndrewL likes a 100mm Z1 on his large Hei Hei - i.e., it has a very slack head angle which might not work on a smaller bike, but he finds it works fine for him.

Stop obsessing about the head angle on the old King Kahuna, it rides remarkably well with the Z1, and is in my opinion irrelevent to the TT/stem length ratio question

For my riding a super long stem casues the biggest problems in the steep downwards stuff as they put your centre of gravity closer to the front axle line. On fork compression your CofG moves forward and with the long stem this means more over the bar experiences as the CofG moves beyond the front axle line.

For me a longer stem also makes the steering rather ordinary and has a negative effect on the handling. The 150mm stem on the Orange is a prime example of that.

 

[Anthony]

The same factor may explain why AndrewL likes a 100mm Z1 on his large Hei Hei - i.e., it has a very slack head angle which might not work on a smaller bike, but he finds it works fine for him.

Stop obsessing about the head angle on the old King Kahuna, it rides remarkably well with the Z1, and is in my opinion irrelevent to the TT/stem length ratio question
For my riding a super long stem casues the biggest problems in the steep downwards stuff as they put your centre of gravity closer to the front axle line. On fork compression your CofG moves forward and with the long stem this means more over the bar experiences as the CofG moves beyond the front axle line.
For me a longer stem also makes the steering rather ordinary and has a negative effect on the handling. The 150mm stem on the Orange is a prime example of that.

I don't know, first he accuses me of obsessing, then all the points he makes are ones that confirm I was right.

Long stems were in vogue when forks were rigid. When short-travel forks came in, stems got shorter and when long-travel forks came in stems got even shorter. That's a fact and it isn't a coincidence, it's an inevitable consequence of the geometry changes required when you run such a large difference between min and max compression. And shorter stems require longer frames, and vice versa

So to get back to Neill's point, I was surprised that he said he would be happy with a 140 stem, as most people would consider that to be 'too long' for a bike with a decent fork. And if, on further consideration, he decided that he wouldn't really want such a long stem, that could change the judgement over whether the 16.25 Merlin was 'big enough'.

 

[guybe]

One thing really puzzle me when measuring the Kona's frames, everybody have different way doing it, I always go for centre b/b to the very top of seat post tube, when it's 19" in length , this mean the frame is 18" in size, some people measure that way, if it's 19" and they think is it's 19" which it's not, I have a 20" Lavadome, it's 21" from centre b/b to top of seatpost tube, and Kona dont make a 21" frame as far I know, just my 2 cents.

 

[neilll]

So to get back to Neill's point, I was surprised that he said he would be happy with a 140 stem, as most people would consider that to be 'too long' for a bike with a decent fork. And if, on further consideration, he decided that he wouldn't really want such a long stem, that could change the judgement over whether the 16.25 Merlin was 'big enough'.

Every bike I have ridden in the last 20 years has had stems of between 130mm and 140mm so i don't know any difference to be honest

My current bikes all have 130mm stems and I don't feel stretched or COG being overly 'forward'.

Should I not have such long stems then? :? :? :?