Cyclocross bike sizing advice sought

dhobiwallah

Hi all, I'm a dyed in the wool MTBer so feel a bit shy coming over here as I haven't shaved my legs or anything

I'm looking at doing a challenge event (Scotland Coast-to-coast) next year which consists of trail running, kayaking and cycling. The cycling is both on and off road, with the tarmac being the lions share. With that in mind a cyclocross bike seems ideal.

I am now in the strange world of 105, ultegra and cm sizing - well away from my comfort zone of XT, XTR and inches!

Anyway, looking to do this on the cheap (this will be a one-off), so eBay it is. Just need advice as to what size to buy. I am 5' 8.5" (174cm) with slightly short legs for my height (31" 'cycling inseam' - ie to the floor not trouser sizing).

All the bikes I am looking at in auctions seem to be oversized. Is cyclocross a sport exclusively for 7 foot tall viking warriors; into which I step as a chunky hobbit? (I'm no lightweight either - don't want to buckle the wheels...)

Kinesis website as an example puts me bang in the middle of a 54cm frame. But the adverts I am reading are full of "56cm frame - I am 6'2" and fits like a glove). Which makes me worry that I'll have to downsize to a 52cm or smaller - which are as rare as hen's teeth in the auctions...

Half the stuff I have found online recommends sizing down from a road frame, while the other half doesn't....

Advice greatly received...

TheMewster

Hi, I got myself a cyclocross bike recently, normally ride a 60cm Trek, went down to a 58cm Cannondale cross bike and dropped by saddle by 1cm when I set it up. Seems perfect to me, not noticed it being significantly less efficient to pedal but can still throw it around, bunnyhop etc. I'm 6'2" by the way....

Monty Dog

I suggest you size down from your road bike size, so probably from 54 to 52cm. Consideration for CX is that the bike 'ride height' is 1-2cm higher than a road bike (higher BB + longer forks + fatter tyres), so a bit of extra toptube clearance is important if you need to put your feet down on uneven terrain. Also, you tend to move around a bit more on the bike offroad as your search for grip, or hang-off the back for drop-offs etc. I run my CX bikes with less saddle to bar drop too - a deep tuck isn't really necessary as you're rarely going fast enough for aerodynamics to matter - plus with lots of saddle lackback for rear wheel grip and a slightly shorter stem - put too much weight over the front wheel and you'll loose-it, whereas a rear-wheel slide is more manageable and can help with tight corners.

gwillis

I'm 5ft 8 and 31" leg I've got a 51cm caadx and it fits like a glove . Best bit is you can pick a caadx 105 up fou under a grand at the moment.
I use my regularly instead of my carbon bike and it's capable of road work no problem .

woolwich

Good advice above.
It's a no brainer mate, particularly if you are buying from ebay and therefore unable to sit on one first. If you size small, you will get the benefits of extra standover and you can always fit a longer stem and extra setback seatpin.
Take a gamble on a large and you will have no room for adjustment down and potentially finish with very swollen parts.
Remember these bikes have toptubes almost as high as roadbikes generally. A too large frame could shatter your confidence in an unfamiliar style of bike very quickly. Once you have it sussed though they are incredibly capable offroad. Good luck.

dhobiwallah

Thanks for the replies guys.

So the general consensus seems to be to size down. I'm assuming that is because (reading between the lines) that standover height seems to be one of the most important considerations. Pretty much the opposite of MTB sizing where top tube length is all; altering the stem length alters the steering characteristics so isn't used to tune fit. (120mm is like the rudder on a barge; something to be laughed at on 20 year old bikes! 60mm, and even shorter is pretty common now). But then I suppose frame builders take standover as a given requirement, so it is already factored in.

There also seems to be a variability in manufacturer's sizing (though still not as much as in mtb with crazy swooping top tubes and suspension pivots). Based on the fact that frame size included the amount of seat post protruding above the top-tube, which could be any length! I'm guessing this is where the size down or not debate comes from.

If the manufacturer significantly changes frame geometry for CX then the standover for a given seat tube length can be quite a bit larger than a manufacturer who keeps similar geometry to their road range, based on how far down the seat tube the top tube meets.

As an unscientific approximation, comparing the CAADX and the Kinesis as an example there is approx 3cm difference between the 'c-c seattube' length minus the bb drop on a 54cm frame; basically a whole size!

Or am I talking total bobbins?

Thanks for the pointer gwillis, but both my (eBay) MTBs combined came to about that - and I'm an MTBer! My budget is about a third of that, so 2nd hand definitely. When I first started testing the water I was outbid on a small 6 year old Scott CX team which went for under 300 quid, so they are out there. (Beginning to wish I'd bid higher now)

Since the event is next Sep It is looking like my best bet is to look at the end of the CX season rather than the beginning!

Since those listing auctions don't always put 'cyclocross' or 'CX' in the title are there any brands I should be looking for?

So for I have Scott CX, Cannondale CAADX, Kenesis crosslight, croix der fer and uncle John....

Cheers

gwillis

Happy to help I'm generally a 53/54cm frame so sizing down is correct. Plenty of deals out there on eBay .amother option is do a self build over time

NickintheLakes

dhobiwallah wrote:

Thanks for the replies guys.

So the general consensus seems to be to size down. I'm assuming that is because (reading between the lines) that standover height seems to be one of the most important considerations. Pretty much the opposite of MTB sizing where top tube length is all; altering the stem length alters the steering characteristics so isn't used to tune fit. (120mm is like the rudder on a barge; something to be laughed at on 20 year old bikes! 60mm, and even shorter is pretty common now). But then I suppose frame builders take standover as a given requirement, so it is already factored in.

There also seems to be a variability in manufacturer's sizing (though still not as much as in mtb with crazy swooping top tubes and suspension pivots). Based on the fact that frame size included the amount of seat post protruding above the top-tube, which could be any length! I'm guessing this is where the size down or not debate comes from.

If the manufacturer significantly changes frame geometry for CX then the standover for a given seat tube length can be quite a bit larger than a manufacturer who keeps similar geometry to their road range, based on how far down the seat tube the top tube meets.

As an unscientific approximation, comparing the CAADX and the Kinesis as an example there is approx 3cm difference between the 'c-c seattube' length minus the bb drop on a 54cm frame; basically a whole size!

Or am I talking total bobbins?

Thanks for the pointer gwillis, but both my (eBay) MTBs combined came to about that - and I'm an MTBer! My budget is about a third of that, so 2nd hand definitely. When I first started testing the water I was outbid on a small 6 year old Scott CX team which went for under 300 quid, so they are out there. (Beginning to wish I'd bid higher now)

Since the event is next Sep It is looking like my best bet is to look at the end of the CX season rather than the beginning!

Since those listing auctions don't always put 'cyclocross' or 'CX' in the title are there any brands I should be looking for?

So for I have Scott CX, Cannondale CAADX, Kenesis crosslight, croix der fer and uncle John....

Cheers

Giant TCX1 2013 - plenty of bang for your buck + linear pull brakes (quality ones too) so no cant' chatter.

They are sized large - XS fits my 5' 8" height (or lack of!) spot on.

http://www.giant-bicycles.com/en-gb/bik ... 842/56836/