Was just checking out the Evil DOC and it states top tube length as "virtual", is that the same as "effective"?
tt ? Is virtual the same as effective?
- Thread starter Evel Monkey
- Start date
Yes, the effective top tube is considered to be the same as Evil's virtual tob tube. Just with a somewhat relaxed seat angle the higher you raise the saddle the longer the distance is going to be from the saddle to the stem. So in reality a set top tube length wont really tell you that much, unless you have the seat jacked as far down as it will go.
Thanks heikkihall.
Yeah, that should be correct but maybe DW or someone else can say for sure if they are the same. "Virtual" and "effective" top tube measurements came to be when people started using sloping top tubes, because the actual length of the tube changes if it's sloping, and the angle of slope is different on different bikes. The key is the distance between the tt/ht junction and the seat post, measured as a level, horizontal line. It's a helpful measurement when comparing different bikes, but since different companies do it differently you gotta be careful. (Old school bikes had horizontal top tubes so it was easy to just measure the tube center to center.) Heikki makes a great point that if the seat angle is way slack (like on an imperial or many dh bikes), raising the seat also moves it back significantly, which will change the actual distance between the seat and bars. (This was also true on older, non-sloping rigs.) But it doesn't change the "effective" measurement of the top tube, since that is always the same based on the point along the horizontal line I described above where the seat post intercepts. And yeah you can just slide your seat along the rails to change the distance but that will effect how your weight is distributed over the bike.
Yikes, there's one from the too much information department!
Yikes, there's one from the too much information department!
not really unless it's just stating the obvious, which it was for me.
In any case i opened the link to this thread so i could make an inane quip that went something like this: effective and and virtual toptube measurement are virtually effectively interchanged.
now as lame as that was there was a point (don't I sound like a 7th grade teacher), it doesn't seem like there is a real convention. In a similar way to how a lot of geometry measurements are published the top tube measurement is used liberally at the discretion of the company. For instance, norco uses the term "total toptube" to basically just replace "effective ~ " meanwhile you'll find differentiations in sizing while using the same units. For example on a road bike the same effective size as another one one maker will list the size as say 56 while the other lists it at 53 and neither of them will measure either of those figures according to the conventions of BB to toptube center or BB center to top of seat post.
it's just a load of silliness, ride the one that fits, which kinda means you gotta get measured and have a feel for what you need and then measure the bike.
one of the many reasons i went and got a custom bike.
In any case i opened the link to this thread so i could make an inane quip that went something like this: effective and and virtual toptube measurement are virtually effectively interchanged.
now as lame as that was there was a point (don't I sound like a 7th grade teacher), it doesn't seem like there is a real convention. In a similar way to how a lot of geometry measurements are published the top tube measurement is used liberally at the discretion of the company. For instance, norco uses the term "total toptube" to basically just replace "effective ~ " meanwhile you'll find differentiations in sizing while using the same units. For example on a road bike the same effective size as another one one maker will list the size as say 56 while the other lists it at 53 and neither of them will measure either of those figures according to the conventions of BB to toptube center or BB center to top of seat post.
it's just a load of silliness, ride the one that fits, which kinda means you gotta get measured and have a feel for what you need and then measure the bike.
one of the many reasons i went and got a custom bike.