Author Topic: Top Tube length (Read 4729 times)

JT71 · « **on:** May 20, 2008, 04:46 PM »

can anyone here honestly say that they NEED a 21.00 rather than say a 20.75?
(the question arose today when stelladave asked me the length of me top tube...I'm sure was my bike
he was talking about, I didn't know so i checked the specs)

I've heard it said a lot, I need a long top tube, gotta be 21.00 nothing less, I'm too big.

but does it really matter? honestly?

get a ruler out (yes, the one you use to measure your chipolata will do) and see how small 0.25 is. it's what, about 5.5mm, some fat grips would make more difference, or a different stem.

now if you are a pro, or even one of these young new riders riding hours and hours on end doing fancy tricks maybe you'd notice, but I still doubt it.

I'm pretty sure anything between 20.00 and 21.00 is just fine and you'd never tell.

what do you all think?

rodslovechild · « **Reply #1 on:** May 20, 2008, 04:50 PM »

i cant see it makes that much difference cos peoples stance on the bike is different too so weight distribution would be different for each rider, it must all be done on averages and the middle average person for each height suits the geometry used

does that make sense

zed4130 · « **Reply #2 on:** May 20, 2008, 04:53 PM »

TBH 20,5 doesnt feel much difference to my new one that has 20.75 and my old robbo had a 18tt and was fine with a xl stem, i prefere short and stout , like me

HEYWOOD BMX · « **Reply #3 on:** May 20, 2008, 08:00 PM »

I have ridden 20.5 frames for years,tried a 20 but it felt too cramped.I have tried 21 inchers and they felt too long,so I stick with 20.5.I have had frames from loads of different companies and all the 20.5 felt great.I guess it`s whatever you feel comfortable on....

kev-s · « **Reply #4 on:** May 20, 2008, 09:05 PM »

i used to ride a dirtbike with a 20in tt and found it cramped and as im long legged my knees were always close to catching the stem/bars i changed to a holmes which is a 21in tt and ive never had any probs again and will only ride 21in top tubed frames, an inch can make a big difference and not just in frame sizes

TwoBobRob · « **Reply #5 on:** May 20, 2008, 11:16 PM »

I tend to agree with the .25" thing. There is a very real difference between how a 20 and 21" frame rides, but as for the smaller increments - well, I'm not too sure. There are so many other factors to consider; headtube angle, seat tube angle, overall wheelbase etc....

I dunno. I think maybe I don't have enough years left in me to be arsed with the more minute dimensions. 74.5 Headtube angle and a longish TT seem to suit me, so I'll be sticking to that for the foreseeable future

Lazarou · « **Reply #6 on:** May 20, 2008, 11:20 PM »

I've ridden 21" toptubes as far back as i remember but around 1996 i bought a 20.5 thinking it wouldn't make any difference but it did! So i sold it to Philbert.

I totally lost interest in the subject when companies (T1 were first i think) started the 20.6, 20.875, shite, that was pointless and annoying.

wussy67 · « **Reply #7 on:** May 20, 2008, 11:42 PM »

last year i rode a supercross with a 21.5 top tube and it felt ok then i swapped it for a team ripper 21.25 top tube made a huge difference, on my first gate i smashed my knees on the bars, so i had to change stem and put some spacers in to get the feel right again, so i"d say .25 makes a huge difference and i"m sure theres plenty of women who"d agree

Trev · « **Reply #8 on:** May 21, 2008, 12:30 AM »

I still can't tell the difference. but obviously it must make some sort of difference otherwise the companies wouldn't make them in different sizes.
but i sell stems which are different sizes, so surely that must also be a factor.
but then again, i'm probably not the best person to ask. i will ride any bike with any top tube size and get use to it.
maybe it's my downfall, but i'll ride any bike with any top tube size, any handlebar height and width and not complain about it. i am used to an era where we didn't get size options, so will ride anything and get use to it.
i think too many people are getting picky for no real reason. (i'm ready to get shot down for that comment)
maybe because of my standard of riding, it doesn't realy make a difference. maybe when you get to an expert level you might be able to notice these things more. until i get to that level, i cannot comment.

jedi · « **Reply #9 on:** May 21, 2008, 09:49 AM »

good point trev.
you will get used to whatever you get

zed4130 · « **Reply #10 on:** May 21, 2008, 12:24 PM »

Quote from: jedi on May 21, 2008, 09:49 AM

good point trev.
you will get used to whatever you get

trev can ride any bike ,

Stella Dave · « **Reply #11 on:** May 29, 2008, 11:45 AM »

I'm just goin on wot I've been told by pro's. I'm 6' so apprently it's 21" or 20.75" minimum. Makes sense I think.

magna13 · « **Reply #12 on:** May 29, 2008, 01:17 PM »

gotta be 20.5 minimum for me, im just to tall! i struggle on my burner, really need a profile xl stem or tioga invert

pickle · « **Reply #13 on:** May 29, 2008, 01:22 PM »

struggling on your Burner has nothing to do with the top tube! maybe more the geometry!

but being 6' 2" i have a 21.25" or something TT and it always feels tight and cramped when i get on someone elses bike

Jt · « **Reply #14 on:** May 29, 2008, 01:25 PM »

jimmy summervile..he can definately say it...

'longer the better' said jimmy, whilst musing over an attempt on annabel chongs world anal attempt.

on a more serious note..i dont know too much about the finer details of your sport( new school

), but a quarter of an inch is only important to women...

other factors on a bike can be adjusted enough to compensate for that amount of extra length

bars, seat rails, crank length, wheel location in rear drop out etc

just my ( probably bollocks) 2p

pickle · « **Reply #15 on:** May 29, 2008, 01:43 PM »

Quote from: J.T on May 29, 2008, 01:25 PM

jimmy summervile..he can definately say it...

'longer the better' said jimmy, whilst musing over an attempt on annabel chongs world anal attempt.

on a more serious note..i dont know too much about the finer details of your sport( new school ), but a quarter of an inch is only important to women...

other factors on a bike can be adjusted enough to compensate for that amount of extra length

bars, seat rails, crank length, wheel location in rear drop out etc

just my ( probably bollocks) 2p

mate you've got it really bad with the whole Jimmy sumerville thing aint ya?

but i think you're right regards some of the components, stem, bars and so on can make a diference

evamedia · « **Reply #16 on:** May 29, 2008, 01:59 PM »

wheel location changes the back end, not the front

Jt · « **Reply #17 on:** May 29, 2008, 03:27 PM »

Quote from: evamedia on May 29, 2008, 01:59 PM

wheel location changes the back end, not the front

i know, thats why i put rear drop out

you could get maybe a cm or more there....this giving the bike a longer feel

evamedia · « **Reply #18 on:** May 29, 2008, 03:52 PM »

Keep digging J.T lol

Jt · « **Reply #19 on:** May 29, 2008, 03:55 PM »

me no understand your astrophysical aproach to this....

please explain ?

evamedia · « **Reply #20 on:** May 29, 2008, 03:59 PM »

We're talking about making your bike feel longer,

your feet are on the pedals, you need to get the bars further away to make it feel longer, rear wheel location ain't doing that.

moley · « **Reply #21 on:** May 29, 2008, 04:00 PM »

Call me an idiot but I never thought about TT length until I wanted an OS racer that didn't cause me to bang my knees on the bars.

TT length is a myth.

Surely its the distance the BB shell is in relation to the headset that makes the difference.

I have 2 Haro's

An old 87 Haro Group One RS1 and a newer early 90's Haro Group One.

The old haro has a 20" TT and The Newer 20.5" TT.

The big difference is where the BB is located.

On the newer Haro it is about 2-3 inches back.

Therefore giving more room up front which would be better for the taller rider!!!

Jt · « **Reply #22 on:** May 29, 2008, 04:13 PM »

Quote from: evamedia on May 29, 2008, 03:59 PM

We're talking about making your bike feel longer,

your feet are on the pedals, you need to get the bars further away to make it feel longer, rear wheel location ain't doing that.

hmm..still not getting you. if you move the wheel back, the bike will feel longer, because it is actually longer

end to end/hub to hub, its longer...my point being, the debate ( if you can call it that) centre's around the need to go that bit bigger in length of top tube, to the tune of 1/4 of an inch...and that there is technically no need to do that, cos you can raise half an inch easy by moving stuff about, inlcuding your wheel to give you that extra length, which would therefore change the handling characteristic of the bike...

as opposed to buying a new, longer by a 1/4 inch frame...

there would also be an arguement on studying/utilising the varieities of geometry used by the different manufacturers, as this could have a greater impact on your style than say the magical quarter of an inch...see above post by moley..it would appear he is coming from the same place as me.

anyway, what the fook would i know

i'm off digging again..catch you new schoolers later

TwoBobRob · « **Reply #23 on:** May 29, 2008, 09:25 PM »

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..

Jt · « **Reply #24 on:** May 29, 2008, 09:30 PM »

Quote from: TwoBobRob on May 29, 2008, 09:25 PM

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..

but would a quarter of an inch made such a big difference as to make you want/need to get a new one