[Canyon48]

Hi All,

I’ve been thinking about a tt bike – yeah I know they are really silly things, but it really suits the type of riding I get to do with my limited time.

I’m 178 cm and I usually ride a Medium (54cm frame) – 52cm downtube 54cm top tube. I’m between sizes small and medium really, but I tend to prefer longer bikes (for my gangly arms).

I’ve got the option of buying a small TT frame (46cm downtube and 52cm top tube). My head is telling me that a small TT frame with a long stem and long seat tube would be ideal (reduce frontal area etc).

I’ve ridden my other half’s small (46cm downtube and 52cm top tube) road bike and, aside from a stupidly short stem, I have absolutely no issues (ignoring the toe overlap, but that doesn’t bother me as I’m used to it from mudguards anyway).

Opinions?

Cheers!

Topic

[Canyon48]

So, funnily enough, it fits

So, funnily enough, it fits me fine more or less. I’ve got the saddle way back and a 110mm stem, the seatpost is also a bit longer than is ideal (as the bottom of it was cut down a bit).

Here it is half built up with an Ultegra drivetrain, HED carbon trispoke that I got second hand and a Mavic Kysrium which I’m laser cutting a (hopefully carbon) disc wheel cover for.

I also need to swap the aero bars, because the ones on the bike currently have been cut too short for my lanky arms.

[Canyon48]

davel wrote:

davel wrote:

I’m about your height, and my Argon 18 TT bike is spot on in a size S – 53 seat, 53.5 top tube. Normally an M, but it varies between manufacturers. Whenever I’m between sizes I tend to size down, and the drop looks about the same as mine, but a 52 top tube would be too much of a squeeze for me, and if you go too small it will mess with the handling (but my handling is pretty crap, especially on a TT bike, so I’m pretty risk-averse when it comes to sizing). I’d take a punt on it being too small for you, too. Try it if you can, first: if you haven’t done TTs, the position will probably feel weird, but if you can give it a bash on a trainer, tweaking the position, you’ll know whether it’s too small and whether any size issues can be rectified by whacking a longer stem on. Edit – sorry, just saw the post where you said you’d bought it! Good luck – get used to it on the trainer first, if you can. It might be manageable if it’s on the limit and you just want to try a couple of 10/25s, but if you can tell it’s not right on the trainer, I wouldn’t race it. A frame that’s too much of a squeeze for me doing tris would bugger my run up. And if you got it for a decent price, you can always resell it if you can’t get it to work.

Yeah, my best guess is that its likely to be too small. My other half is 5′ 8 and she rides a Specialized road bike which is comparable in size to the frame I bought and I’ve never had any issues on that bike aside from the stem being far too short.

I’ve got Ultegra chainset and mechs left over from upgrading my Canyon, so my intention is to build it and sell it if I don’t fit!

I’ve just looked at how the effective top tube was measured, looks like it wasn’t measured centre to centre – so I think the actual ETT is about 53cm

[davel]

I’m about your height, and my
I’m about your height, and my Argon 18 TT bike is spot on in a size S – 53 seat, 53.5 top tube. Normally an M, but it varies between manufacturers. Whenever I’m between sizes I tend to size down, and the drop looks about the same as mine, but a 52 top tube would be too much of a squeeze for me, and if you go too small it will mess with the handling (but my handling is pretty crap, especially on a TT bike, so I’m pretty risk-averse when it comes to sizing). I’d take a punt on it being too small for you, too.

Try it if you can, first: if you haven’t done TTs, the position will probably feel weird, but if you can give it a bash on a trainer, tweaking the position, you’ll know whether it’s too small and whether any size issues can be rectified by whacking a longer stem on.

Edit – sorry, just saw the post where you said you’d bought it! Good luck – get used to it on the trainer first, if you can. It might be manageable if it’s on the limit and you just want to try a couple of 10/25s, but if you can tell it’s not right on the trainer, I wouldn’t race it. A frame that’s too much of a squeeze for me doing tris would bugger my run up. And if you got it for a decent price, you can always resell it if you can’t get it to work.

[Canyon48]

Simon E wrote:

Most TT bikes in size Small are too big for me (162cm) so a Small may be fine for you – Giant Trinity and PX are two that I know really only really suit 5’6″ upwards. Mind you, a 52cm top tube is pretty short for someone who is 5’10” but less of an issue if you have proportionately long limbs and shorter torso for your height. Could you try before you buy?

I have heard that people often *used to* size down for TT bikes, particularly with the older tt bikes (the frame I bought is 2006).

*from what I’ve read sizing down is no longer needed as modern tt bikes have geometry adjusted.

The other benefit I have is that my other half is a qualified bike fitter!

[Canyon48]

Thanks for the responses.

Thanks for the responses.

Didn’t have the option to try first, but I bought it anyway! If it really doesn’t fit, I’m going to build it up with all the spare parts I have laying around before selling it.

mtbtomo wrote:

Blimey, I’m 5ft 10 and ride a 56 road bike and similar TT bike. A smaller frame might make the front end too low, which you might think would be aero, but you could end up with a lot less power and your head stuck up. 52 would be seriously small for someone 5ft 10 I think, even on a TT bike

56?! That’s a bit surprising!

I think I’m pushing it a bit with a 52cm top tube, it’s a good 3 cm shorter than what I’m used to, but I guess that’s an excuse to run a mahoosive stem.

Here’s a pic of the frame.

The seatpost is about the height that I will run it in the pic and the drop doesn’t look too far off what I’d expect. I have about 100 from my saddle to the top of my bars on my road bikes and even then I spend almost all my time on the drops which means my hands are a good 5 cm lower.

[mtbtomo]

Blimey, I’m 5ft 10 and ride a
Blimey, I’m 5ft 10 and ride a 56 road bike and similar TT bike.

A smaller frame might make the front end too low, which you might think would be aero, but you could end up with a lot less power and your head stuck up.

52 would be seriously small for someone 5ft 10 I think, even on a TT bike

[Simon E]

Most TT bikes in size Small

Most TT bikes in size Small are too big for me (162cm) so a Small may be fine for you – Giant Trinity and PX are two that I know really only really suit 5’6″ upwards. Mind you, a 52cm top tube is pretty short for someone who is 5’10” but less of an issue if you have proportionately long limbs and shorter torso for your height. Could you try before you buy?

[Author]

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