TT/Tri frame to Aero Road Bike

[Nooch]

Saw an interesting frame pop up on craigslist and am pursuing it, as it's not a lot out of pocket if it doesn't work out.. It's a TT/Tri frame, but by my (admittedly not great) eyes the angles don't seem too out of the norm for a frame my size (50-52cm).

The long and short of the question is, if it were built as a true TT/Tri frame, how substantially different would it be, perform, act with road bars than in true TT/Tri trim, if at all?

[oldpotatoe]

Saw an interesting frame pop up on craigslist and am pursuing it, as it's not a lot out of pocket if it doesn't work out.. It's a TT/Tri frame, but by my (admittedly not great) eyes the angles don't seem too out of the norm for a frame my size (50-52cm).

The long and short of the question is, if it were built as a true TT/Tri frame, how substantially different would it be, perform, act with road bars than in true TT/Tri trim, if at all?

Steeper seat tube angle so you can easily reach real tri/TT bars and still have something approaching 'kops'..if your femurs are such that you can use a steep ST angle..with drop bars, then sure, it should work. Remember, on steep ST angles, to get something around 'kops'(not a big C constant, just a place to start), moving your saddle aft, it effectively lengthens the top tube length.

[carpediemracing]

First, ignore the seat tube angle for handling. Seat tube angle only has to do with the base position of a saddle relative to the BB, meaning if you stick a saddle on a given post a steeper seat tube angle places the saddle more forward. You can adjust your saddle, within limitations, to get the saddle->BB relationship correct. STA basically moves your "potential saddle position window" forward or backward.

More significant is the head tube angle. TT/Tri bikes typically have a shallower head tube angle so that even with the same amount of trail the bike tends to go in a straight line. It also pushes the front wheel more forward so you don't feel like you're going to flip over the bars. I had a TT bike not designed for aero bars (relatively shallow STA, HTA) and when I pushed my saddle forward and put aero bars on the bike felt like it was behind me, not under me. A shallow head tube angle, even for the same amount of trail, will put the wheel further forward and reduce that feeling of "about to flip over the front of the bike".

So what's that mean for a TT->road conversion? You'll have less weight on the front wheel. Personally that's the worst for me, I hate it when I can't weigh the front end of the bike in a turn.

My main frame is a steep STA bike - 75.5 deg - with a normal front end - 73 HTA, 43mm rake. I asked for a frame such that I would use a 12 cm stem with normal reach bars and, as it turns out, 14.5 cm stems with compact/short reach bars.

The STA does nothing by itself to the bike, it just positions me over the BB (I have very short quads). HTA makes the bike reasonably agile in turns and such.

Fuji sold an aero road bike that was actually their TT frame also. Toyota United used them, I think their sprinter was the first one to use it publicly as a road bike (Dominguez?). I don't know of any other TT bikes that would be well suited for drop bars in a typical road bike scenario.

[oliver1850]

I have a TT frame that I'm probably going to build as a road bike.

On a smallish frame you may be able to achieve the same seated position (as your normal road bike) relative to the BB with post setback and saddle rail adjustment. Then you only have to worry about the front end. If you like your bike to handle on the slow side, it may be perfect. If you want quicker handling you may still be able to achieve it by changing the fork. If you have the front geo and the specs of the fork that the frame was designed for that would go a long way towards predicting how it's going to handle, and whether you might be able to change the handling with a fork swap.

[KidWok]

I seem to recall Carlos Sastre doing this at the Tour one year. Maybe it was an uphill TT? Couldn't find any pics.

If it fits you and you can ride it harder, faster, and/or more comfortably, go for it!

Tai

[Nooch]

So looks like the angles are 73/73 -- I think my pronto is at 73.5/72.5... So on average, that looks like it should work for a road application, right?

[oliver1850]

So looks like the angles are 73/73 -- I think my pronto is at 73.5/72.5... So on average, that looks like it should work for a road application, right?


Sounds pretty much like road bike geo to me. Early 52 cm CAADs were 74/73 with 43 mm rake and Serottas were 74/72 with 47 mm rake. I should look up a LeMond but I am sleepy.

[oldpotatoe]

So looks like the angles are 73/73 -- I think my pronto is at 73.5/72.5... So on average, that looks like it should work for a road application, right?

Yep..compare top tube length and head tube length but it 'should' work.

73 ST angle is very slack for a TT/Tri frame.

[seppa]

73 ST angle is very slack for a TT/Tri frame.

I wish they we're all like that, I don't understand how people can ride their saddles over the BB, just don't feel good. I've really been considering using a small road frame as a TT bike lately, something I really wish I pursued doing over winter last year.

[Nooch]

well, should be fun -- we shall see (and see if the measurements were correct!)

https://farm6.staticflickr.com/5578/14771746060_7a5f26f6d0_z.jpg
(https://flic.kr/p/ovk4sU)IMG_20140817_180900 (https://flic.kr/p/ovk4sU) by TrickImaging (https://www.flickr.com/people/54300653@N02/), on Flickr

[oliver1850]

I wish they we're all like that, I don't understand how people can ride their saddles over the BB, just don't feel good. I've really been considering using a small road frame as a TT bike lately, something I really wish I pursued doing over winter last year.

I have a tri geek friend that rides a setback post turned around backwards, on a TT specific frame no less. Seems like overkill to me but he's often in the top 3 on the bike at some pretty big events. Must work for some (short femurs?).

[Shin Getter]

I seem to recall Carlos Sastre doing this at the Tour one year. Maybe it was an uphill TT? Couldn't find any pics.

If it fits you and you can ride it harder, faster, and/or more comfortably, go for it!

Tai

Pros will use a road bike if there is any kind of significant amounts of climbing and/or lots of technical descending.

If you watch any of the early season races in the middle east where they don't use TT bikes...you'll see road bikes set up "TT style", running deep wheels and their saddles pushed a bit forward. Some ride with extension...some don't.

I've seen Garmin run their S5's with TT bars and extensions at a few races.

I think this is Romandie in '13.
http://www.lmcbobcats.com/sports/cycle/2012-13/photos/AndrewTalansky.jpg

[Jason E]

If you watch any of the early season races in the middle east where they don't use TT bikes...you'll see road bikes set up "TT style", running deep wheels and their saddles pushed a bit forward. Some ride with extension...some don't.



Wasn't this more of a logistics issue in getting the bikes back and forth?


Sent from my iPad using Tapatalk HD

[seppa]

Wasn't this more of a logistics issue in getting the bikes back and forth?




+1, I know thats been the case for races like tour of quatar, heck they even agreed no clip on aero bars or anything, I think theres a video from the past few years on youtube

[carpediemracing]

+1, I know thats been the case for races like tour of quatar, heck they even agreed no clip on aero bars or anything, I think theres a video from the past few years on youtube

Generally speaking when they do this they say the bike has to be "mass start legal". That means the wheels have to pass whatever UCI impact tests (for example I think the Zipp 1080 hasn't been tested or doesn't pass), bars can't end pointing forward/up, I'm not sure if there are other road bike rules that would make a TT bike illegal. Tour of PA, a U23 race, did this also.

The goal is to reduce travel/support logistics for the competitors and their teams.

[carpediemracing]

well, should be fun -- we shall see (and see if the measurements were correct!)
https://farm6.staticflickr.com/5578/14771746060_7a5f26f6d0_z.jpg


Curious to see how the geometry works out. Seat tube looks slack, is that accurate or just lens distortion?

Now you need some really tall aero wheels, the flat top drop bars, blah blah blah :)

[Nooch]

Curious to see how the geometry works out. Seat tube looks slack, is that accurate or just lens distortion?

Now you need some really tall aero wheels, the flat top drop bars, blah blah blah :)

it may actually have to get moved as quickly as it comes in.... just got some news about another machine that I was waiting on.... just a matter of space!