[Miker J]

Excuse the post on this Turner board as I'm not an official Turner owner yet but do have a nice new shiny Burner on the way. Posting on the Turner board seems to produce much more insightful replys compared to posting on the other MTBR boards. Replys such as "Dude, that should get you some major air" are not always that helpfull.

Anyway here's the question. What's your take on the variations in TT length for a given size frame from different manufacturers. Do you think each has deliberately created different TT length for a given size frame to produce given handling characteristics? I've been mountian biking for over 10 years and have had large bike frames that have TTs that have ranged from a HT Trek (current ride) with and effective TT of 25.2 to a Blur (fell apart, warrantied, sold) with a TT of 23.3, to a Surly 1x1 that's somewhere in the middle. Obviously each frame seems to handle differently in respect to different TT length. With stem size/degree, HA, and fork axel to crown being constant a shorter TT will make a sharper handling bike but may sacrifice stability on the downhills. What's your opinion on this?

What brought this to my attention most recently was Turner's choice of a 23.9 TT for the Burner. I had to take the plunge and order the frame without a test ride. An expensive experiment. Normally I'd have thought it to be a bit short for a _XC_ oriented bike. However, I'm hoping that when combined with it's relatively lax HA and a 100mm fork the bike won't be too unstable on the decents while still doing well on the tight single track.

Sort of just thinking out loud here.

Mike

 

[Flying Wombat]

I think you have it right, stability is also a function of wheelbase, and a slacker head angle combined with a longer fork will "kick out" the front end. My guess is that you will love the handling of the burner. My small 'spot has a top tube length about 1/2" shorter than my previous bike but feels more stable due to a 69 degree head angle. The steep seat tube seems to put you in the center of the bike also helps. I dont know how to describe it, but it works for most people.

 

[tscheezy]

Both of you have made very valid points. A lot of it comes down to what application the bike is destined for: long tts for low, forward xc racer positions on hardtails, and short tts for high, rearward bias on freeride bikes.

This still does not really account for why there are huge disparities between manufacturers aiming for a single discipline. On opposite ends of the spectrum we would find Fisher with his totally ripped-off Genesis geometry (long tt, short stem) and on the other end Jamis with their incredibly short bikes and long stems. That seems to be a matter of corporate philosophy which begets frame design which begets design habit and even brand recognition.

We all actually benefit from this. Folks with short legs and long torso/arms will generally find a better fit from a different brand than those with long legs and short torso/arms. Woe is it to those who don't fit on Turners though...

 

[CrashTheDOG]

On opposite ends of the spectrum we would find...

So where does Turner stand in the spectrum or TT lengths? Average?

 

[tscheezy]

In a very unscientific survey, I'd call them in the upper 1/3 of the bell-shaped curve distribution of tt lengths for a given size among reasonably similar builders. I generally just pay attention to tts in my size (~19" or large), but Ells are very long across the board. A large Yeti is about 24.4" in tt though I could fit on a medium which has a rather short 23.4". A large Jamis XLT is 23.2" in the tt. Some brands just fit me better than others. It is also largely a matter of what you are used to.

 

[Roy]

Woe is it to those who don't fit on Turners though...

Not a problem, as Turner does custom. Hey, it's only money.

 

[Cary]

I personally believe the solution is to not look at how a manufacture lables their frames. Small, medium and large mean different things to different people. When I look at a frame, I look at effective top tube length, the most important measurement. Seattube angle will effect the effective cockpit length slightly, but not enough to make a difference in my opinion (if you are using effective toptube lengths, a 1 degree different in seattube able will affect effective cockpict length by at most about 0.4cm). This measurement combined with stem length is going to tell you the most about how a bike fits.

 

[CrashTheDOG]

Not a problem, as Turner does custom.

Are you sure? Typically for a manufacturer to offer custom geometry they have to build their frames in house, such as Seven or Ventana, which Turner does not. And even then, adding suspension to the mix typically limits the amount of changes to small tweaks, which may include TT length, rather than a fully custom geometry.

 

[tscheezy]

Turner used to be flexible on this front back when you could order directly from them. They really seem to want to go through dealers these days and I don't think they want to migrate from stock configurations any more. I asked for custom cable routing on my Spot (hardly a tall order) and about the possibility of getting a polished frame and offered to pay extra for it but was denied.

 

[Roy]

Are you sure? Typically for a manufacturer to offer custom geometry they have to build their frames in house, such as Seven or Ventana, which Turner does not. And even then, adding suspension to the mix typically limits the amount of changes to small tweaks, which may include TT length, rather than a fully custom geometry.

They used to do custom, and it was quite reasonable - it only added $200 to the frame cost (plus 2+ months of time). Don't know if they still would consider it, though.