A better way to measure frame sizes?

don

Well-Known Member
It's my Birthday!
I saw this on the Sinister board after noticing last week that Transition had the reach and stack measurements on their site.

http://www.sicklines.com/2008/12/18/...k-a-good-idea/

It seems like a really good way to get the correct cockpit size of modern frames.

reach_stack.jpg
 

Norm

Mayor McCheese
Team MTBNJ Halter's
Wounldn't that ignore a more severe seat tube angle (as measured against the "stack" line in the picture)?
 

jdog

Shop: Halter's Cycles
Shop Keep
Why do you like this??

I am not sure what this would give you that an effective seat-tube length, bb drop and headtube length wouldn't give?

A slacker seatube angle would give a longer reach but you would never know it w/ this setup.. I would guess??


.. i just went and read the sicklines post. This makes sense if you are running the seat all the way down and standing while pedaling I would guess.
 
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Maurice

New Member
This makes sense in free-ride, downhill or dirt-jump applications, where you spend most time out of the saddle.
 

don

Well-Known Member
It's my Birthday!
Wounldn't that ignore a more severe seat tube angle (as measured against the "stack" line in the picture)?

If I understand what you are saying then yes. Some of you might remember the Evil Imperial with a very kicked back seat tube angle. I had one and it was a great riding frame, but impossible to compare to others on paper with ETT length.
 

don

Well-Known Member
It's my Birthday!
Why do you like this??

I am not sure what this would give you that an effective seat-tube length, bb drop and headtube length wouldn't give?

A slacker seatube angle would give a longer reach but you would never know it w/ this setup.. I would guess??


.. i just went and read the sicklines post. This makes sense if you are running the seat all the way down and standing while pedaling I would guess.

Like Maurice and you said, maybe this measurement makes more sense in lowered seat applications like DH, FR and DJ bikes. But from some other threads I've read about it, there might be some value with it to measure more XC types of setups too.

A slacker seatube angle will give you more TT length but could measure the same "Reach" (as on the diagram) as another frame w/ a steeper ST angle. I don't know that much about rider sizing/setup but with many of the seat and seatpost (zero and various laybacks) combinations you can have a few inches to play with front to back and not really need to worry about seattube angle?

And it seems like this measurement could help riders go from 26" - 29" wheel frames (or vice-versa) without worrying about HT length.

I thought part of this post from Dave Turner was interesting on mtbr (http://forums.mtbr.com/showthread.php?t=477481&page=2) :

I have always intended the cockpit reach to be the distance from the BB to the Top of the HT, as head angle will not effect the amount of room between the feet and hands when measured this way. This is a great way to compare bikes from different makers as I have ranted on about in the past to some of you, that without a consistent way to compare from frame to frame a TT on a bike without a somewhat normal ST angle terminating at the BB center is worthless.

Stack! When Sam mentioned that their idea was a second measurement, this one verticle, I was totally for it. Now, when we put the RFX and the 5 Spot R&S on the spec sheet no one will be confused about how different they would sit on it. As I have mentioned int he past, at least once! The difference between the RFX and 5 Spot in fit and trail feel is immense, and part of the difference will be conceivable with Stack, then throw in there slacker angles, shorter Reach and longer chainstays and Voila! Different sister

I'm not a Turner homer, but I do like to hear what Dave has to say. I really respect his frames and his designs. To me, he and Transition are not trying to pass another standard like 15mm thru-axles but add another way to measure frame fit. Not sure if this will overtake ETT and some other measurements but it might be worth adding it for some of us to compare frames. At the very least I am interested to see who will use it and where it will go.
 
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