I am thinking of buying a new frame to replace my 11 year old carbon Scott Strike. The Scott is the main bike I ride and the shape seems to fit me. I guess that means I want to replace it with a frame the same sort of size and shape.

When I look at various sites they talk about Top Tube length, Head Angle, seat angle, chain stay length …

How many of these measurements do I need to concern myself with?

I would have thought the distance and angles between the saddle and the bars was relevant and the the saddle and pedals would be the main ones that affect riding position. Unfortunately these aren’t shown when just buying the frame.

Help me work out what size frame I need for one of these : http://www.on-one.co.uk/i/q/FRTITFTMCARRS/titus-ftm-carbon-frame-and-monarch-shock or if there is a similar frame that would fit me better.

downtube length
BB height
Head angle.
nothing else really matters for (stood up) handling.

chainstays mostly fall in the same ballpark unless you are looking at street/DJ frames or DH bikes at either end of the scale.

Definitely top tube length.

a couple of degrees difference between seattube angles will make two frames with identical TT lengths completely different sizes.

2 frames with the same head angle but different length top tubes, would also make them different sizes.

All tubes make a difference. I’d suggest finding a frame as close to the size and geometry as the one that you already have. Unless you’re planning on using new components such as different travel forks.

I am thinking that the new bike will have slightly more travel. The Scott is about 100mm each end and the Titus is 135mm at the back so I was going for similar at the front.

TT length – is this the actual length of the piece of tube or the distance from the saddle to the bars? If it is just the length of tube then surely a leaning back seat post will change the distance between saddle and bars making it inaccurate.

I don’t suppose anyone has a Titus built up do they?

Effective top tube length, the horizontal distance, is what I go by.

http://www.titusti.com/2010/bikes/ftm_carbon.php

tbh if i was a carbon weave – i’d spontainiously undo at the sight of your mass 😯

Querty – thanks for the picture, not for the weight comment!

My CARBON Scott has been fine for 11 years of heavy riding and numerous large and violent crashes.

It looks like I need to worry most about the Effective Top Tube length and the seat tube for my sizing requirements.

Check this out

Jus measured up the Scott and unless I have got this wrong, it has significantly different geometry to the Titus.

Effective TT length = 22.5 which is shorter than a small Titus
Stand over height = 32 which is taller that a large Titus
Wheel base = 45 which is longer than any Titus

I guess I need to start trawling through the demo fleets and try stuff.

2 frames with the same head angle but different length top tubes, would also make them different sizes.

Well. no not necessarily if the downtube was the same length, BB height and chainstays the same, they’d ride exactly the same while standing, for a longer/shorter TT just the seat angle would need to be different but what with the 3″ of seat rail fore and aft adjustment and around 2″ difference between an inline and layback seatposts they could be set-up to ride exactly the same even sat down.

Effective top tube length, the horizontal distance, is what I go by.

Thats what I meant.

WCA – don’t forget stem length can equalize a cockpit length so ETT ain’t imperitive to have the same, also geometry fashions / designs / improvements have evolved since the birth of your Spark, best bet is to get a demo ride but they can be tricky to find

the Titus looks like a bargain!