Top Tube length

[TwoBobRob]

To me?   Would it bollocks   


Like I said in my first post, you can really feel the difference between a 20" and a 21".   And I'm sure there's summat to be felt in a 0.5" variation, but smaller than that?  I'm really not sure.  It wouldn't affect my purchase I don't think.

[harris]

21"tt for me just feels right,not worried about all these 0. increments .21 "will do
i do ride shorter frames but never really bothered as they aint my main ride.

[moley]

Right...............


I'm not an authority on these things, but;


You don't want to confuse wheelbase with TT length.  Also, you don't want to assume that lengthening the front end by sticking a xxl stem on it will make it the same as a longer TT frame.

Moley; your old bike must have one lazy-assed seat tube angle yeah?  and your more modern bike has a more conventional steeper seat tube.  This explains the difference in the position of your BB shells.  Assuming of course that you're measuring frames only and not frame and forks, coz if you were, then you'd have to start looking at headtube angles as well and that's far too much work...  My point being, TT length is not a myth these days as most all seat tube angles are very very similar. You're not gonna see 2-3 inches of difference in anything nowadays, so the TT length is very relevant now.

The most fundamental difference I've noticed is the longer the TT the 'flatter' the bike jumps. It always seemed to me that the longer bikes fly nicer, less likely to loop out or nosedive.  A very short frame with a bloody great long stem on it wouldn't give this effect.   Might just be me though..

It makes sense.   After years of experimentation.  The geometry of bikes has grown into a standard.   Once you have found the best geometry.  Why Stray from it.

I dont know to much about NS bikes (or OS bikes for that matter) and I was really referring to my OS Bikes with the TT length. 

[TwoBobRob]

You've got it   

Small tweaks these days based on current riding styles and fashions, nowt outrageous.

[moley]

Whats the difference with Flatland bikes?

Shorter back ends for spinning etc, etc!!!

[jedi]

rode my fit cleveland 21" today.it felt way better than my 20.75 fit flow and handled better cos of the short rear end. it couldve rode like a dog but i would have got used to it

[TwoBobRob]

Whats the difference with Flatland bikes?

Shorter back ends for spinning etc, etc!!!

To simplify it enormously,  flatland bikes are very short and very steep.  They are extremely task specific.  And cool as fcuk   

[Bettyswallocks]

Looks like this debate is gonna run and run.....

I'm 5'5" and ride a 20.6" TT and my brothers got a 21" TT ooerr mrs... 

I can tell the differance between the 2 bikes...   

[Philbert]

i notice any change on my bikes! maybe because i ride often, having spent many a year designing bike frames and studying cycle engineering, the main contributing factor to a bike length is in the toptube length, but whats noticable is probably only in 1/2 inches. anything smaller than this dinomination won't be that noticable, what is noticable in small dinominations are things like head angles, back end lengths, even rear tyre sizes!

i've ridden a 20.5 for the last 6 years, before that i rode a 20. made a huge difference, floated in the air nicer, wasn't quite so whippy for tech though, and helped my back loads! a few weeks ago moved on to i believe a 20.6. thats how it came! can't say as though i notice any difference but its what the kids think sounds 'cool' and thats what sells these days so i guess companies have to go with it

heres a breakdown of what different lengths and angles do to a bike:

toptube:
overall length differential - shorter for twitchy, longer for flowy riding

headangle:
74.5 most common balance, 75 makes front end steaper and more twitchy, will feel longer but wheelbase shorter. one reason why some race frames run a 75 headangle is due to running a 20x1.75 tyre as opposed to a 20x2.125 rebalances the overall angle of the front end back to a 74.5 as the backend drops ever so slightly in height, thus adjusting the headangle

seatangle:
biggest contributer to bb position - slacker angle brings a shorter riding position at front end but feels longer to sit on, steeper brings the bb back for longer riding position but to sit on feels more upright and shorter.

chainstay length:
imo what changes everything these days - probably the biggest change in bmx over the last few years, the common length 10 years ago would be between 14 1/4 to 15 inches, gave a stable ride particularly on the track and is still used by some race companies i believe, shortening the backend however brings the balancing pivotal point closer to the rider so manual rolls and tech trickery is much easier, standard byke co also use this method of a shorter rear end on the track too for faster gate starts and more ability in where you want to put the bike, has a much snappier feel! most common length these days are a 13.75 rear end but companies like fly bikes are pioneering even shorter back ends running i think a 13.25 on their tierra frame

[Jt]

 

[darkersomeday]

you dont fook about do you philbo?

shit in there i never knew dude,

props