I am looking at buying my first TT bike, and am wondering if I should size smaller or larger than my road bike. My road bike is 46cm. I am looking at a 2016 cannondale slice as triuk have it in stock at a very good price (I'm aware it's more a triathalon bike, and not uci legal, but as it will be for club and open tts, it doesn't bother me). I'm debating whether I should go for a 44 or a 48. I'm 5'2" with a 30in inseam.
TT bike sizing help
- Thread starter rivers
- Start date
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vickster
Legendary Member
Ask Tri UK
I have, been waiting a few days for a reply due to the current situation. So thought I would see if anyone has some advice.Ask Tri UK
HarryTheDog
Guru
- Location
- Basildon Essex
My daughter is 5ft 2 and a ex National junior 25 mile TT champion ( 2nd in the 10) and getting a TT bike to properly fit ( over 6 years ago) was a real nightmare.
At the time my daughter was in a semi pro team and got measured properly. To be perfect she basically needed a bike with a effective top tube of something silly like 48cm which was impossible to find. The bike sizes you mention are all to do with the seat post ie 46cm , you need to go through the geometry charts of the bikes you want and look at the effective top tube length. At the time the only bike with a short enough TT was a 650B planet X ( TT 47cm) but we did not want 650B as team would not keep 650B wheels, her team did not supply TT bikes only road. We found others with a TT of around 49-50 but they were advertised by manufacturers who actually did not make them or only produced 10 a year or something a year . In the end we had to wait 3 months for fuji to make a batch of 10 ( only 10 for the whole year) XXS Fuji D6 with a TT of 49.5. She got it a week before the nationals and 2nd ride on it ever came 2nd( Alice Barns was first but a year older) . ( entered the 25 for a giggle having never done one before and came 1st) .
I am 5ft 5 and I have ridden that TT bike and fits me better than her so short Top Tube as possible is probably the order of the day. The ultra small TT bikes were like rocking horse pooh when I was looking years ago but
now more people are doing TT's and triathlons it may be easier to find a very small TT bike, you may want to look at 650B wheeled bikes for a proper fit.
It is always possible to make yourself fit on a bigger bike depends on how flexible you are and whether you are interested in theoretical fit perfection.
At the time my daughter was in a semi pro team and got measured properly. To be perfect she basically needed a bike with a effective top tube of something silly like 48cm which was impossible to find. The bike sizes you mention are all to do with the seat post ie 46cm , you need to go through the geometry charts of the bikes you want and look at the effective top tube length. At the time the only bike with a short enough TT was a 650B planet X ( TT 47cm) but we did not want 650B as team would not keep 650B wheels, her team did not supply TT bikes only road. We found others with a TT of around 49-50 but they were advertised by manufacturers who actually did not make them or only produced 10 a year or something a year . In the end we had to wait 3 months for fuji to make a batch of 10 ( only 10 for the whole year) XXS Fuji D6 with a TT of 49.5. She got it a week before the nationals and 2nd ride on it ever came 2nd( Alice Barns was first but a year older) . ( entered the 25 for a giggle having never done one before and came 1st) .
I am 5ft 5 and I have ridden that TT bike and fits me better than her so short Top Tube as possible is probably the order of the day. The ultra small TT bikes were like rocking horse pooh when I was looking years ago but
now more people are doing TT's and triathlons it may be easier to find a very small TT bike, you may want to look at 650B wheeled bikes for a proper fit.
It is always possible to make yourself fit on a bigger bike depends on how flexible you are and whether you are interested in theoretical fit perfection.
Thanks for the info. The effective top tube length on my road bike is 50.5 and on my CX bike is 51.5. The cannondale is 45 for the 44cm and 47 for the 48cm.
HarryTheDog
Guru
- Location
- Basildon Essex
Helps if I had read your original post properly, wow that slice is tiny, I would probably go for the 47cm with the 48 top tube as maybe a better fit and the 44 has 650B wheels which reduces your wheel and tyre choices ( Also I think bigger wheels = faster but other people may argue with that) .. Pity it wasnt available in my daughters time. ( her road bikes were 50cm top tube BTW)
I was leaning towards the 48 to be honest. A friend of mine has a slice and a supersix, and has the same size in both. The way cannondale size their bikes keeps you the same across the range apparently. Looking at the super six geometry, I would opt for a 48 as the 44 looks to be too small.
TT bike sizing is just to personal to say this bike will fit you . Ive always been advised to buy a frame a size smaller than my road bike . In fact my first bike ( specialized shiv ) The manager refused to let me buy it as he thought the next size down was a better fit for me . He had to order that in but did it at the same sale price as the one on the showroom floor .
If you go smaller you can adjust everything to fit you . Longer stem , lower drop and raise the seat post . If you go bigger you lose all of those aero gains a TT bike gives you .
If you go smaller you can adjust everything to fit you . Longer stem , lower drop and raise the seat post . If you go bigger you lose all of those aero gains a TT bike gives you .
So just compared the stack and reach on all four bikes (my two and both the cannondales). The stack/reach on my road bike is 510/375, cx bike is 523/380. The stack/reach on the 44 is 465/360 and the 48 is 487/375. Obviously the slack is going to be lower on the slice. But what about the reach? Should it be similar?
You cant compare . You know the size of the bike that your legs can handle , then go smaller . Thats all that matters really , anything else can be changed . Thats my opinion anyway .
Update. Spoke to my bike fitter in the end. He recommended I opt for the 48 for various reasons. Which is what I did in the end. I still have a few tweeks to make, and I'm on the waiting list once my fitter starts bike fits again. But, here's the new bike, and will be speaking to my LBS about deep section wheels for racing sometime in the near future. Cables need a bit of tidying, and I'm going to keep my eyes peeled for a 36 or 38 cm base bar. I'm also debating new tyres for the current wheels. Torn between GP5000s and Pirelli PZeros. Race wheels will end up with something tubeless most likely.
now the pain starts 