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Drevil

· drev-il, not Dr. Evil!
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3,913 Posts
Discussion starter · #1 ·
...I was just curious why more frames aren't designed with lower top tubes? With the bigger wheels comes less standover because the top tube has to attach to a higher point (off the ground). Here are reasons I can think of why a framemaker would resist, and possible solutions:
  1. Less room on seattube for waterbottle : Put waterbottle mount under down tube instead, or use a side release cage and a shorter bottle.
  2. Less heel clearance at the seatstays : Bow them inwards where the heels may hit, and definitely run disc brakes on the rear.
  3. Limited choices of seatposts that long : Team up with custom seatpost makers such as Black Sheep, et. al.
  4. A lot of leverage on the frame from the long seatpost : Strengthen potential weak points with braces or more material
  5. Frame "twisting" out of plane? Not sure about this one, but it seems to me that a smaller triangle wouldn't flex as easily.
  6. Harder to shoulder the bike : This ain't cyclocross. Roll the bike! :p
A lower top tube seems safer since you have to fall further down to do some damage to your body. Also, they look better to me, as long as they don't droop downwards (sorry Spicer fans!) Plus, you'd potentially get more flex from the seatpost, making for a cushier ride. All of these advantages would work for both tall and short people, eh?

BTW, Heavens knows that I definitely don't need a new frame! But, here's to dreaming with Photoshop :D:D:D

Image


Here's the actual bike:

 
#3 ·
Yes, I'm too hung up on the quality of the Photoshopping to give an opinion. Even the crack in the railroad tie in the background is repositioned correctly.

Do you do this (graphics of one sort or another) for a living?
 
#4 ·
Drevil said:
...I was just curious why more frames aren't designed with lower top tubes?
Click to expand...
'Cause not all of us are short. ;)

Aren't Niners designed with 410mm post in mind?

Some pics from my machine for your cause though...

LP

PS - Good hanging out with you and crew this weekend. Good times.
 

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#7 ·
and the 'by ricky D.' looks like it was carved into the wall!

about the lowered TT thing: my upcoming custom bike actually has a higher TT junction than the stock bike i am coming off of, but still plenty of clearance. builder said it is stronger and doesnt want to mess with lots of bracing, etc.

his point is... why lower it? besides clearance for clarence thomas. it makes the bike weaker and you need a custom seatpost. the extra bracing weighs more than the extra ST... or something.

in any case. can you do some more cool photoshopping? make your bike into a chopper!
 
#8 ·
pswann said:
Yes, I'm too hung up on the quality of the Photoshopping to give an opinion. Even the crack in the railroad tie in the background is repositioned correctly.
Click to expand...
Ah yes...but he couldn't reproduce the Maxxis logo on the rear tire from where he moved the rear seatstays now could he?

Slacker...:D

LP
 
#9 ·
"[*]Less heel clearance at the seatstays : Bow them inwards where the heels may hit, and definitely run disc brakes on the rear."

Tire clearence for the seatstays. You would have to make a really sharp bend for tire clearence. Not sure what you mean by "bow them inwards"? Bow them where? There is a tire in the way. Anyway - that is the main issue I see.
 
#12 · (Edited)
1) Bottle under the down tube is great in dry climates, not s great in the UK....esp if you ride through a farm yard then take a nice big gulp of water with added "body" yuck!

2) Less room on the back for seatstays so you have to join them on the top-tube rather than the seat tube.

Image

Image


3) Long seat posts (within reason) are available, RooX make a 430mm one....making the frame only work with one make / type of seat post is another headache for customers and limits your market.

4) Like the Salsa 29er? (and the big pink Solitude) Standover room plus a "normal" back end. Some people don't like the look of a dropped toptube / brace but some people don't likes drooped tubes either :rolleyes: :D

5) Smaller triangles are "stiffer" in the vertical plane (for a given tube set) as to twisting out of plane (head tube > seat tube vertical) is a different matter that I will have to have a think about.

6) Carry the bike? 29ers are the right height to lean on the bars while pushing :thumbsup:

I think that stand over is slightly over-rated, as long as you have 3-4" more is wasted.

Now what bugs me is short head tubes (90mm) then having 2" rise bars and a 30mm stack of spacers.....Grrrrr :mad:

Alex

Drevil said:
...I was just curious why more frames aren't designed with lower top tubes? With the bigger wheels comes less standover because the top tube has to attach to a higher point (off the ground). Here are reasons I can think of why a framemaker would resist, and possible solutions:
  1. Less room on seattube for waterbottle : Put waterbottle mount under down tube instead, or use a side release cage and a shorter bottle.
  2. Less heel clearance at the seatstays : Bow them inwards where the heels may hit, and definitely run disc brakes on the rear.
  3. Limited choices of seatposts that long : Team up with custom seatpost makers such as Black Sheep, et. al.
  4. A lot of leverage on the frame from the long seatpost : Strengthen potential weak points with braces or more material
  5. Frame "twisting" out of plane? Not sure about this one, but it seems to me that a smaller triangle wouldn't flex as easily.
  6. Harder to shoulder the bike : This ain't cyclocross. Roll the bike! :p
A lower top tube seems safer since you have to fall further down to do some damage to your body. Also, they look better to me, as long as they don't droop downwards (sorry Spicer fans!) Plus, you'd potentially get more flex from the seatpost, making for a cushier ride. All of these advantages would work for both tall and short people, eh?

BTW, Heavens knows that I definitely don't need a new frame! But, here's to dreaming with Photoshop :D:D:D

Image


Here's the actual bike:

Click to expand...
 
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Discussion starter · #14 ·
robpennell said:
"
[*]Less heel clearance at the seatstays : Bow them inwards where the heels may hit, and definitely run disc brakes on the rear."

Tire clearence for the seatstays. You would have to make a really sharp bend for tire clearence. Not sure what you mean by "bow them inwards"? Bow them where? There is a tire in the way. Anyway - that is the main issue I see.
Click to expand...
Y'know, having a slight s-curved seatstay when looking at it from the top. I've heard a couple of reasons why it's done (heel clearance and to put the v-brake bosses closer to the centerline of the frame). Of course you'd bow it outwards where the tire sits. You can kinda see it on my frame:
 

Attachments

#16 ·
Drevil said:
Y'know, having a slight s-curved seatstay when looking at it from the top. I've heard a couple of reasons why it's done (heel clearance and to put the v-brake bosses closer to the centerline of the frame). Of course you'd bow it outwards where the tire sits. You can kinda see it on my frame:
Click to expand...
I'm with ya but the lower the seatstays are the closer the wide part (tire) is to pedal rotation.
 
Discussion starter · #18 ·
robpennell said:
I'm with ya but the lower the seatstays are the closer the wide part (tire) is to pedal rotation.
Click to expand...
Ding ding! The light bulb went off in my head after reading SSP's second reason, which you just confirmed. Thanks Rob and Alex!
 
#20 ·
with you. my seat tube length (c-c) has gone from 17" 11 years ago (kona cindercone 20") to 14.5" c-c on my new tIF. Taking advantage of the long strong seatpins, lessening standover and increasing comfort...its all good. at the moment i am maxed out on a 380mm moots, or a wee bitty room to spare on a thomson 410mm. it helps i like the aesthetics as well...

in terms of how far i would go, i think i am there. cant see any real advantages of an even shorter seat tube...i also have v brakes on a 14.5" c-c kelly 29er and i dont connect with them as i ride. (i do tend tobe a touch pigeon toed tho') and there are no tyre clearance or bottle issues (i use 2 large bottles within the front triangle)...so yup. there we go.
 
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