DF4 Sizing for Sprinting
 

Hi all,

Hope you're all good, I'm about to purchase a DF4 for a focus on sprinting for 2021 season (assuming it happens!) but I'm getting mixed advice on sizing.

I'm 172cm, inseam of 80cm. Dolans size guide puts me on a 55cm frame, but after been burned by the PlanetX size guide in the past (frame was way too small) I'm wondering if I should go a size bigger.
Is this still a norm in the track world to go bigger? Have bike manufactures factored this in to their size guides?

My current track bike is a 51cm (379 reach) and feels really undersized, even after sticking a 120mm stem on to increase reach to 499 it still feels small.

My logic was to go a size bigger than Dolan suggests, a 57cm frame (434 reach) with a 100mm stem, brining reach to 534 total. A jump of 35mm from my current small setup. Lots of room to adjust up or down then.
Geometry wise stacks and seat tubes are identical, only the top tube changes between the 55 and 57.

I tried a DF4 before Christmas which had 3T bars and a 130mm stem on it which felt good, but nobody was too sure what size it was (55 or 57) and due to lockdown I don't have access to it now, I've a poor photo but I can't post it here yet because I haven't been a member long enough.

Am I overthinking this? Perhaps. Have I gotten sizing wrong before and don't wanna get screwed again? Absolutely.

Really appreciate any advice thank you.

It does seem that sizing has definitely been leaning toward going bigger for sprinting.

I'm 5'9" and I'm on a 57 DF4 with a 130mm and scattos. I could easily go bigger.. I'm not on a particularly big bike compared to some too. I have friends in the club who aren't much bigger than me that are on 59s and 61 fujis.

Only advice? Fling a leg over a DF4 you know the size of an try.

Go 57,

I was on a 57 Dolan, but my fitter wanted me on a larger frame - I was running a 150 stem on it.

Yeah see Dolan would've even put you on on a 55 so that would've been that been tiny for you.

Out of curiosity whats your height?

I'm 5'10", so not terribly tall. But my fitter didn't want me on a 59 Dolan, she wanted me on a 61 Fuji or Felt (the new version) or a Large Look or Argon. I went Argon.

I should note, TT length was not the issue. Rather, it was HT and stack. I’m incredibly flexible for my age, but she wanted the bars higher so I could more easily get my back flat and keep my elbows at a 90 degree bend for improved aerodynamics.

I'm also 5'10", riding a 57 DF4 with a 130 stem and secretly wishing I had another 1-2cm. Was previously on a 55 DF3.

This is really off topic but curious. What stem 150mm you using? Thomson Elite x4 is super stiff and nice but expensive.

And @babyPuke I guess you using Thomson as well?

After I bought Thomson, I don't want to try anything else except Thomson. Any alternative that equivalent to Thomson recommendation? I would be appreciated.

3T makes stems up to 150. I have an older 17 degree one and a newer Apto in 6 degree. I don't like the reverse threaded faceplate on the Apto, but it has two bolts at the steertube, whereas the older 17 degree only has one. The older one was purchased used from a friend, whom I think got it off eBay.

The weird thing is, you cannot seem to find 3T stems greater than 130 in the US. I had to order the Aptos from Europe - I think I went through Wiggle. They were cheap when I got them, like $40 a piece. (I also ordered a 140 and a few pairs of cleats to get free shipping.)

Zipp offers a 140 in one of its aluminum versions.

As for 3T vs Thomson, I am a big fan of the X4 stems. They have tested to be the third stiffest option after the Pro Sprint and Zipp. But they are much cheaper and come in more sizes, angles. So far, the 3T Apto is stiff enough. I haven't noticed any major issues with it.

Velobike NZ also has a 150 stem. I'm not sure how stiff it is. I'm probably going to switch to the Velobike sprint bars once they are available. They are quite long, and very shallow.

Thomson stems are great, but only go to 130mm. The old 3T ARX stems with 2 bolt steerer and 4 bolt faceplate were right up there just under Thomson for stiffness and can be had in 140 & 150. They're rare these days but they do come up 2nd hand from time to time. I have them from 120 up to 150mm and will never part with mine!

Any well built alloy stem is going to be more than stiff enough for 99.9% of riders. Using a well built stem, any flex you feel will most likely be in your bars or forks/steerer tube or wheel.

Yeah, @Altimis Thompson is my jam. Wish they came in at least 140, though.

It's worth noting that 140, 150mm stems aren't absurd. Modern track bars like the Scatto are at least 20mm shorter than normal handlebars. So, if you are used to running a 120mm stem on your road bike, switching to Scattos (at 20mm shorter) will call for a 20mm longer stem.

I remember going into bike shops asking for 140mm stems and the staff looking at me like I don't know what I'm talking about.

More on stem length.

I have allways sized my frames based on a 120mm stem And have always used 120mm stems.
To the OP your not a tall guy if you think a 57 with a 100mm stem will work for you so will a 55 with a 120mm stem and you can always go 130mm if it feels cramped or 110mm if it feels too long.
I’m pretty sure either would work for you and if you have to go longer than 130 KCNC make 140 and 150 stems that are readily available.