PTW

Anyone shed some light on tt bike dimensions please?
I ride a 56cm road bike with a 55cm top tube (c-c),
the tt bike im looking at is a 55cm aero frame with a 548 top tube, 73degree head angle,76degree seat angle, 490 seat tube. im 5ft11" btw.
Whilst this seems the obvious choice for me, a triathlete friend reckons i should go for a 52cm frame with a 524 top tube, 460 seat tube, 72.5 head angle and a 76 degree seat angle.
He recommends this just to get "lower" on the bike.
Whilst i understand where he is coming from surely going this much smaller would just make me too cramped wouldnt it?
Whilst on this subject, before i part with my cash i was hoping that some really nice person with a suitable tt bike would let me have a quick spin if possible (i know im a cheeky bugger for asking), the reason being that i had a bad mountain bike crash a few years ago and shattered my left shoulder and this does limit the positions i can achieve on the bike.
Obviously i dont want to make an expensive mistake if i can help it.
Thanks in advance for any help.

Little kev's frame would suit you as a tt. Don't forget Tri's, jacks of 3 trades, masters of none. No matter how low you are on a bike, if you're in any discomfort your not gonna be "aerodynamic". Best thing for you at the mo, is borrow a pair of clip on bars from a ( not so local, friendly chippie) and give them a whirl on your road bike and then make any adjustments to suit, when thats done transfer all the measurements to a suitable frame.

That should have read ( local, not so friendly chippie)!

Cheers kev, i will give you a ring mate.

I'm no tester but the 'ideal' position is for a flat back and forearms paralel to the road. Of course, I echo what Kev says hear which is that your first thought should be a degree of comfort. Start off with that and see if you can tweak the position as you go. As you get more used to being lo and aero you can push the position a bit further with the help of adjustable stems and bars.

Davey C wrote

I'm no tester

Too true mate.

Sorry Davey, couldn't resist .

Davey's right but, equally, Kevin's thoughts on comfort become of increasing importance with increased distance and therefore increased time in the saddle although my theory seems to be of no relevance to the top UK testers who seem able to keep that classic aero position in 100's, 12-hour and 24-hour TT's and I clearly remember Nik Gardiner passing me (on several occasions ) in the 24-hour and being amazed that he kept up the aero position for the full duration.

Out of interest, what distances are you targetting?

Hi Alfie, To start with i am going to try 10s & 25s, i will do as many club individual tts as my shifts allow and im also planning on the magic dragon series.
Thereafter who knows?

Not owning a TT bike and having played with the best position I can get on a road bike for some time now, I can say that I think the advice to go for a smaller frame is spot on. I ended up building my own brackets just to move the clip-on tri-bars closer to the saddle, and my level of comfort was instantly transformed.

I haven't actually gone any faster, but that could be because each year I get slightly older, and do less training. A road bike is a long machine, and it's good to stretch out, but trying to stretch out in a tt position results in a LOT of discomfort.

Quote

...increasing impotence with increased distance...

Couldn't agree more. An uncomfortable position is a nightmare for your knackers

Don't forget Tri's, jacks of 3 trades, masters of none. Oh there was that triathlete who had a few good results in a few races, now what was his name now, I forget?.........................oh yes Mr. L. Armstrong

I think you'll find he was a dedicated cyclist when he had "a few good results in a few races".

Boys, boys, armstrong could beat me on a unicycle!!!!
Thanks for your help so far everyone, the general consensus seems to be directing me to the 52cm, (completely the opp of what i thought), just a bit worried about toe overlap ( i know i would be going in a straight line most of time) going that small.
Although i realise that i could be resembling superman on the 56cm!lol
Bloody confusing this tt lark.
Im off mountain biking to clear my head!

Just had a very helpful and intresting phonecall from jeff bruce.
He has offered (with no obligation i might add!) to set me up on a tt bike and discuss my requirements.
Obviously i am extremely grateful for this invaluable offer, but to be honest im also quite dissapointed that nobody thought fit to steer me in jeffs direction sooner.
Surely having someone with jeffs experience so well known in the club and seeing as he has set a number of club members tt bikes up for them we should be using his knowledge to the full.

Thought you were going down the second hand route.

It could have been a lot worse. Someone could have steered you in Wills direction!