Weight Weenies
* FAQ    * Search    * Trending Topics
* Login   * Register
HOME Listings Blog NEW Galleries NEW FAQ Contact About Impressum
It is currently Sun Nov 19, 2017 12:46 am

All times are UTC+01:00





Post new topic  Reply to topic  [ 62 posts ]  Go to page Previous 1 2 3 4 5 Next
Author Message
PostPosted: Fri Sep 08, 2017 3:24 pm 
Offline

Joined: Sat Oct 23, 2010 9:36 am
Posts: 541
Location: Where the permanent autumn is
alcatraz wrote:
... outperform the aero frames and descend properly with disc brakes..



I won't repeat what some poster already excellently summarized above, just to comment on your original 2 points:

1) TT bikes outperform aero frames only because of TT base/extension setup. Cervelo or Felt themselves said (can't recall exactly, which of them) that their aero model (S5 or AR 2014+, respectively) performed equal to their TT bikes in the wind tunnel if steering setup were the same.

2) proper descending even on amateur level has very little to do with disc brakes. What matters is, the cornering skill of the rider plus bike "agility" (several "interconnected" parameters, such as wheelbase, chainstay length, fork characteristics), and, as pointed already out, on all of these any dedicated TT frame is severely lacking.


Top
   
Posted: Fri Sep 08, 2017 3:24 pm 


Top
   
 
PostPosted: Sat Sep 09, 2017 12:39 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
"If steering setup were the same"

This does not simply mean put on clip on bars on an S5 and it'll go side by side on the flat with a TT. The drop bars are quite big compared to a frame integrated base bar. There must be a penalty. Manufacturers love to play on the desires of the customer. Wouldn't trust the selling jargon much. I could trust the forums and the combined indication of several reviews.

It's not easy to integrate a TT handlebar setup onto an aero bike as well as it is on a TT bike. Quite impossible as it's a part of the frame. Are you going to say that those differences don't matter? If I'm going to use a TT handlebar setup I might aswell get a well integrated one.

I have carbon wheels with pretty good brake tracks but even with swissstop princes I can't safely descend. I take risks every time I go over 10 degrees and my area has descents up to 28 percent. I have to change my route to climb the steep side because I can't descend there. (People including kids and dogs are walking the streets, I can see them well ahead but I can't stop in time on carbon, on alloy I could barely but that was when I was slower. Simply, I need to be able to stop)

The last thing I'm going to do is to try and optimize my rim braking in this situation. It's a flawed concept for the roads I ride at my current speeds. Needs some improvement.

At the end I'd like to say I don't understand why some posters have to make their points so arrogantly. I read everything even though I don't reply to it. I take it into consideration. I'll think about it when I go to try some bikes. I love cycling just like you. In the past I have made some decisions that older riders warned me against and they turned out for the better and in the end I've turned them around to the ideas. Thats why I like to explore. If only there were a light weight triathlon bike out there. Those ought to have the best tube profiles. NACA profile is enough. No need for a spaceship. :lol:

/a


Top
   
PostPosted: Sat Sep 09, 2017 12:59 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
How much faster is a triathlon bike compared to a tt bike on the flat?

Like how much does UCI slow us down is basically what I'm asking.

/a


Top
   
PostPosted: Sat Sep 09, 2017 6:03 am 
Offline

Joined: Sat Aug 02, 2014 1:54 pm
Posts: 16
alcatraz wrote:
How much faster is a triathlon bike compared to a tt bike on the flat?

Like how much does UCI slow us down is basically what I'm asking.

/a


Not much. Less now when UCI has "removed" the 3:1 rule so that, for example, deeper section forks can be used. Most tri-bikes handles the penanilty of on-bike storable better though, and can be faster at higher yaw.


Top
   
PostPosted: Sat Sep 09, 2017 7:33 am 
Offline

Joined: Mon Mar 23, 2015 9:47 pm
Posts: 148
alcatraz wrote:
"If steering setup were the same"
[...]
Are you going to say that those differences don't matter?

No, he is not. He is talking about the hypothetical case of the aero road bike having the same steering system and integrated stem than the TT bike.

Concerning braking: Disc brakes are not more powerful than rim brakes if you choose rotors smaller than 180mm. The difference with hydraulic brakes is lever feel. The difference between all disc brakes and rim brakes is wet weather behaviour.

On the SuperSlice with the base bar setup, you'd need to run mechanical disc brakes. You will not get an advantage over rim brakes with alloy brake tracks there except if you are riding in the rain all the time. In fact, the brakes on my road bike (direct mount rim brakes on alloy with SwissStop Flash Pro BXP pads) are more powerful than the TRP Hy/Rd on my CX bike in the dry and about as good in the wet. The disc brakes are better for riding off road with the CX bike of course.


Top
   
PostPosted: Sat Sep 09, 2017 8:34 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
I'm afraid to overheat my rims. On my 58mm rims it's less of a problem but if I have a wheelset with 20mm climbing rims it's a serious problem I think.

I can probably bring the disc brakes to 300 degrees C but I don't dare going over 150 on my rim brake wheels. I can experiment with different high temperature rotors and pads regardless of the wheelset.

Wouldn't you say there are more choices?

Nothing would please me more than to avoid the aero penalty of disc brakes but I hate to hesitate when braking downhill. I don't wish to haul a hydraulic brake system up the mountains either, nor a heavy alloy deep rim. Because in all honesty we don't brake that much, but when we do brake they have to work well. I'm not talking about city riding. I'm talking the worst kind of situation. Narrow switchbacks 10+ degree descent going for multiple kilometers with obstructed view corners, occasional potholes, gravel, oncoming traffic. This is a descending nightmare.

If I brake hard I might warp the rim or blow my inner tube, if I don't brake I could fly off the road at the next switchback or dog running across the road in front. I need to drag the brakes a lot more than I'm comfortable.

This is China. Scenic routes are amazing to ride here, beautiful but they have tourists walking them all the time. They are cut off from regular traffic except for tours and buses which only come occasionally. I haven't had an accident except once with a dog just running out in the middle of a flat city 6 lane street. I endoed over the bars. Bike was fine. I can't blame it. Problem is now I ride even faster. It worries me a bit but I'm watching my periphery a lot more now.

/a


Top
   
PostPosted: Sat Sep 09, 2017 9:26 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
MayhemSWE wrote:
A time trial bike ridden exclusively form the basebar is not going to be any faster than even a standard road bike, let alone more recent aero road bikes. Then you talk about climbing and descending, which would be an even worse use case for the time trial bike. Why do you think professional riders tend to pick standard road bikes (with clip-ons) for mountain time trials? They sure ain't looking to keep their speed down!


Because there are no 6.8kg light tt bikes? Because the fit is only optimized for flats and no consideration was put for the base bars.

Lets say a 200km course consists of 60% flat and 30% ascend to 2000m and 10% descend.

I find it too complicated to decide back and forth between bikes. I ride more arbitrary roads, sometimes very far on flats to get to certain popular climbs. Why haul a sail for 70km to enjoy 20km of climbing and then having to ride 70km back?

/a


Top
   
PostPosted: Sat Sep 09, 2017 9:30 am 
Offline
User avatar

Joined: Wed Apr 25, 2007 10:23 am
Posts: 1272
Location: Pack filler
You're obviously not convinced by people who actually ride and race TT bikes ( and not just 16km) regularly, so go out prove us wrong ;)

Buy a cheapo old PX stealth, that has a slack sta by tt bike standards, or similar, build it up and try it...

_________________
Official cafe stop tester


Top
   
PostPosted: Sat Sep 09, 2017 11:28 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
What if you optimize a TT bike not solely on the TT position alone. Lets say you bring the base bar up a bit (frame size +1) and lower the TT bars. That way the base bars won't be in that extreme low position.

Furthermore base bars need to be a bit longer perhaps and the TT bars further back. This so that you can find a comfort compromise.

Not just set the base bar as a bailout bar like a poster put it but to position them with some precision in an aero/comfortable place. This so that to not always want to ride in a TT-position.

These are still just ideas. Is this completely up the wall crazy or what? I consider my flexibility above average.

/a


Top
   
PostPosted: Sat Sep 09, 2017 11:33 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
jekyll man wrote:
You're obviously not convinced by people who actually ride and race TT bikes ( and not just 16km) regularly, so go out prove us wrong ;)

Buy a cheapo old PX stealth, that has a slack sta by tt bike standards, or similar, build it up and try it...


Their biggest point is the handling. But I think they talk from a TT-position perspective.

A fork with shallow angle is going to be less responsive, that I get.

Second point is the fit not being anything like a road bike. The three contact points though, hands/seat/pedals. Are they way off I wonder?

A road bike's seat is far back. That way the hip angle creates upper body support and unloads the hands/arms. Now consider a TT position forward a little but with a high base bar and low tt-bar. Sure the load will be greater but it's not impossible to get a nice upright position with almost straight arms and hands closer to the "tops".

/a


Top
   
PostPosted: Sat Sep 09, 2017 12:46 pm 
Offline

Joined: Mon Mar 23, 2015 9:47 pm
Posts: 148
I think everything has been said in this thread. Built it up and try for yourself.


Top
   
PostPosted: Sat Sep 09, 2017 1:31 pm 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
Lieblingsleguan wrote:
If you want to mimic roadbike geometry, you'd need to push the saddle farther back than technically possible, mount the base bar very high and would still end up with the unusual head angle.


You said it yourself.

So after these mods, will the bike be slower than an aero bike? Seems almost all the posters think yes.

Aerodynamics will be slightly better, fit and handling will be slightly worse.

How do we quantify the difference?

Is it, a flexible person will be faster while an unflexible one will be slower?

Why is it ok to put clip-on bars on an aero bike to gain speed but taboo to go the opposite approach and make a tt bike more like an aero bike?

/a


Top
   
PostPosted: Sat Sep 09, 2017 3:15 pm 
Offline
User avatar

Joined: Thu Sep 21, 2006 8:54 pm
Posts: 1122
Location: Reading, UK
alcatraz wrote:
How much faster is a triathlon bike compared to a tt bike on the flat?
Like how much does UCI slow us down is basically what I'm asking.
/a


Depends on the definitions you're using. High-end triathlon bikes are designed for, well, triathlons. With all due respect to triathletes, the bike leg is not usually ridden as fast as a pure TT, after all there is a swim before and a run after. Stack and reach are optimized for a comfort-oriented race position.

There aren't so many pure TT bikes any more, by which I mean TT frames built longer and lower, allowing a more extreme aero position. If you're dumping all your energy into a 16km or 40km test, you need to really focus on being aero which generally means low and narrow. Assuming a frame allows you to get low then the particular frame you choose has little impact on race speed, that is much more determined by handlebar setup, wheels, skinsuit, aero helmet.

Coming back to your desire for a TT frame used as a road bike, one point is that TT seat tube angle is steeper than a road frame so will sit you further forward on the bike. That will put more weight on your hands and if you're riding with basebar-only setup, you'll have weight on your hands and only one hand position available. Could get tiring.


Top
   
PostPosted: Sun Sep 10, 2017 1:20 am 
Offline

Joined: Mon Aug 29, 2016 11:19 am
Posts: 388
Makes a lot of sense Miller. I'd put the seat far back and make sure the bars aren't too far forward.

I'm quite lightweight. I always say us lightweights have to be more aero than the middle and heavyweights to keep up on the flats and descents. Your poiny about clothing/helmet is more important is of course true. I like how quiet the bike manufacturers are to the fact that a shoecover makes the same difference as their best aero frame does.

Which frame comes close to NACA profiled tubes without being too bulky I wonder? Seems to me this cannondale has pulled it off quite nicely to find a balance which includes integrated handlebars. I'd like to avoid the truncated profile becuase then I'd be simply better off with a Trek Madone (disc - whenever they come available).

If it's true that the uci has removed the rule that prohibits NACA tubes then we should hopefully start to see really good tr and aero bikes coming out soon.

/a

Image


Top
   
PostPosted: Sun Sep 10, 2017 1:55 am 
Offline

Joined: Fri Apr 21, 2017 3:08 am
Posts: 52
You've evidently made up your mind. Go for it and see what happens.


Top
   
Posted: Sun Sep 10, 2017 1:55 am 


Top
   
 
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 62 posts ]  Go to page Previous 1 2 3 4 5 Next

   Similar Topics   Author   Replies   Views   Last post 
There are no new unread posts for this topic. 2012 Cannondale Slice 5 VS 2014 Stradalli Phantom II

in Road

Alpine318is

1

404

Tue Mar 14, 2017 7:43 am

jekyll man View the latest post

There are no new unread posts for this topic. Attachment(s) Any thoughts on the 2018 Trek emonda SLR rim brake version?

[ Go to page: 1 2 3 4 5 ]

in Road

Windstopper

61

4466

Fri Nov 17, 2017 5:11 am

ClydesdaleChris View the latest post

There are no new unread posts for this topic. Cannondale 2016 Caad 12 and Super Six HM fork difference

[ Go to page: 1 2 ]

in Road

sjoerdth

15

1812

Sun Jun 11, 2017 1:16 pm

snowdevlin View the latest post

There are no new unread posts for this topic. Cannondale Evo Disc

in Road

Hls2k6

7

1070

Sat Jan 07, 2017 12:55 am

stockae92 View the latest post

There are no new unread posts for this topic. Disc brakes : new pads = brake rub??

in Road

Delorre

9

954

Mon Oct 23, 2017 11:36 am

CBJ View the latest post


All times are UTC+01:00


Who is online

Users browsing this forum: alorast, Bing [Bot] and 30 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited