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Re: Why don't we go with a single chainring for tri? [devashish_paul] [ In reply to ]
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Hey DP,

Your post about 5 speed freewheels inspired me to go look I what I had back in the day. Bought my first new "10 speed" in 1970. A Peugeot U08. I couldn't find specs on it. But a friend had a Peugeot PX-10. The specs for that showed a 14x24 freewheel with 45x52 chainrings!
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Re: Why don't we go with a single chainring for tri? [TriTater] [ In reply to ]
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Not that I choose but did my last race IM St George 70.3 with a single chainring. On the first climb (mi 2 of the race) my front derailler cable broke... Did the entire 56mi on a 39! Rode 22.2mi/h... It's a course that I could have use my big chainring many many times. In order to maintain rythm with some guys passing me, I rode on 39 x 11 at rpm well above 100. At 120rpm I was getting close to 30mi/h... Did many burst of around 125-130 rpm to pick some speed on the descent.

I shoot my legs by maintaning a RPM of between 100-110 for most of the race. My run really suffer from this. Going under gear like I did, I suspect that I lost 10-15 minutes, maybe 7-9 minutes on the bike and probably 4-7 minutes on the run for because of over spinning, I had no spring in the legs during the run.

I have a friend that goes single chainring in all his races (53) even in Kona... I think he would be faster by spinning more up the hills but that's what he decided.
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Re: Why don't we go with a single chainring for tri? [TriTater] [ In reply to ]
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front derailleur mount broke on my tri bike a couple of years ago, haven't missed the small chainring at all on my mostly flat or sometimes rolling short races in Texas. I just taped the cable to the tube so it wouldn't bounce around and never even removed the small ring, derailleur or shifter. Reading this I guess I outa take off those extras for the bit of aero/weight gain. Its a 1x10, 53 with 12/25. Haven't dropped a chain, but I pedal continuously at pretty high average cadence from habit after years of commuting on a fixie.

------------------------------------------------------------
some days you're the windshield some days the bug
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Re: Why don't we go with a single chainring for tri? [MTL] [ In reply to ]
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Next time just adjust the low limit screw on the FD clockwise until it can't shift down from the big ring. Would take less than a minute to stop, adjust, get moving again. You would just need to carry a small multi-tool, or stop at tech support.
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Re: Why don't we go with a single chainring for tri? [motoguy128] [ In reply to ]
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motoguy128 wrote:
Triathletes need to mostly ignore any advice, myths, preconceptions, etc from road bicycle racing.

It's not the roadies who keep asking about this kind of stuff. We all watched David Millar drop his chain in the TdF prologue and know that this is a solution in search of a problem.

Kevin

http://kevinmetcalfe.dreamhosters.com
My Strava
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Re: Why don't we go with a single chainring for tri? [motoguy128] [ In reply to ]
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>Fundamentally, racing a clock in a not draft legal TT

What?
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Re: Why don't we go with a single chainring for tri? [trail] [ In reply to ]
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I'd love to run a single ring up front and ditch the front derailleur and shifter. I run 1x11 on my Scalpel and have yet to drop the chain. The new derailleurs with the clutch and the special front chain ring could be developed for road use. Sram has a 1x11 now for cross as well....
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Re: Why don't we go with a single chainring for tri? [SAvan] [ In reply to ]
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SAvan wrote:
Next time just adjust the low limit screw on the FD clockwise until it can't shift down from the big ring. Would take less than a minute to stop, adjust, get moving again. You would just need to carry a small multi-tool, or stop at tech support.

Thanks for the tip, I didn't thought of it.
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Re: Why don't we go with a single chainring for tri? [TriTater] [ In reply to ]
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Here's my Titanflex build with single chainring
(completed this past weekend May 31st, but no long ride report yet given my 10yr old visiting nephew gave me the Flu for the last week)

Dropped nearly half a pound (0.46 lbs) by converting from 2012 SRAM Red (50/34 Red compact crank, TT shifters, Red Derailluers)
to SRAM XX (10spd) Rear derailluer, 11/36 cassette, Wolf Tooth Components wide/narrow 44T chainring. (will use SRAM 46T CX1 Chainring when available to gain back some top end). SRAM 10 speed road shifters and 10 speed mountain bike parts are fully compatible (both use exact actuation)

44T chainring and 36T cassette yields a climbing ratio of 1.22 vs a ratio of 1.21 with the prior compact set up of 34T chainring and 28T cassette cog.
44T chainring and 11T cassette yeilds a top speed ratio of 4.00 vs a ratio of 4.55 with the prior compact set up of 50T chainring and 11T cassette cog
When I switch to 46T CX1 Chainring when available:
46T chainring and 36T cassette cog yeilds a climbing ratio of 1.28 (which is more than enough to climb the steep hills around Bloomington, Indiana easily)
46T chainring and 11T cassette cog yeilds a top speed ratio of 4.18 (just 8% less top end than compact 50/11 gearing so should be good for just about everything)

The XX Cassette Gear spacing is 11,12,14,16,18,21,24,28,32,36 which works great for hilly terrain (Bloomington, Indiana) with constant shifting required.

I hate compact crank's drop from 50t to 34t which often necessitates an upshift or two in the rear derailluer to maintain steady cadence (I'm used to the wider cassette spacing given my mountain bike background) and I hate front derailluers even more!

Bye Bye Front Derailluer, Hello 0.46 pound weight reduction and perfect shifting!
(total bike size XL as pictured below with pedals, computer and bottle holder is 18.15lbs)

pics



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Re: Why don't we go with a single chainring for tri? [TriTater] [ In reply to ]
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Re: Why don't we go with a single chainring for tri? [GTOscott] [ In reply to ]
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Cool setup. Seems like a smart choice of gearing, especially once you get the 46. As folks have said, the lost weight probably doesn't make that big a deal for most tri courses. But I love the simplicity of shifting straight up and down the gear range, and not messing with front shifts.
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Re: Why don't we go with a single chainring for tri? [ridenfish39] [ In reply to ]
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ridenfish39 wrote:
I'd love to run a single ring up front and ditch the front derailleur and shifter. I run 1x11 on my Scalpel and have yet to drop the chain. The new derailleurs with the clutch and the special front chain ring could be developed for road use. Sram has a 1x11 now for cross as well....
I tried running a SRAM clutch mech on my TT bike with a single ring but it was terrible for dropping the chain, it even dropped it on the turbo trainer. It seemed it might even make things worse by being quite slow to take up the chain tension when shifting to a smaller sprocket. So I ditched the clutch mech, and have since been running a Di2 rear mech with a fibrelyte ring designed for single ring use, and it has been quite good for retaining the chain, but it has still come off in my last two TTs so I'm going to have to admit defeat and put a front mech on just to stop the chain from coming off. It makes it fairly pointless going single ring in the first place as the front mech is probably the biggest aero saving.

I have a feeling a major reason MTBs can get away without something to keep the chain on is the much smaller chainrings compared to a TT setup. I once tried a 60T chainring, designed for double ring use, and the chain simply came straight off within a few revolutions if you turned the cranks on a turbo trainer in the top 2 sprockets.
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Re: Why don't we go with a single chainring for tri? [cyclenutnz] [ In reply to ]
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In my last couple Olympic tri's and possibly this sunday I will be in my compact 50T ring the whole race so for some courses seems logical to me. But I'm not throwing down sub 1 hour 40K splits either so not sure how much I gain by lowering a few grams. Must....Keep.....working....on.....engine.....

Wouldn't have worked at Branson a few years ago and def. not Savageman.
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Re: Why don't we go with a single chainring for tri? [Steve Irwin] [ In reply to ]
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Steve Irwin wrote:
ridenfish39 wrote:
I'd love to run a single ring up front and ditch the front derailleur and shifter. I run 1x11 on my Scalpel and have yet to drop the chain. The new derailleurs with the clutch and the special front chain ring could be developed for road use. Sram has a 1x11 now for cross as well....
I tried running a SRAM clutch mech on my TT bike with a single ring but it was terrible for dropping the chain, it even dropped it on the turbo trainer. It seemed it might even make things worse by being quite slow to take up the chain tension when shifting to a smaller sprocket. So I ditched the clutch mech, and have since been running a Di2 rear mech with a fibrelyte ring designed for single ring use, and it has been quite good for retaining the chain, but it has still come off in my last two TTs so I'm going to have to admit defeat and put a front mech on just to stop the chain from coming off. It makes it fairly pointless going single ring in the first place as the front mech is probably the biggest aero saving.

I have a feeling a major reason MTBs can get away without something to keep the chain on is the much smaller chainrings compared to a TT setup. I once tried a 60T chainring, designed for double ring use, and the chain simply came straight off within a few revolutions if you turned the cranks on a turbo trainer in the top 2 sprockets.
The reason it works on the mtb isn't just the clutch rear derailleur. The front chaining has special teeth that are extra long and every other tooth is a lot wider.
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Re: Why don't we go with a single chainring for tri? [ridenfish39] [ In reply to ]
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ridenfish39 wrote:
The reason it works on the mtb isn't just the clutch rear derailleur. The front chaining has special teeth that are extra long and every other tooth is a lot wider.
The fibrelyte guy reckons people use his single rings on MTBs and tell him they work better than the XX1 rings. I just don't think the clutch mech is particularly helpful for road use, I think the main benefit of it is for coping with bumps off road, and most of the time on the road what you really need is a very fast take-up of chain slack when shifting to a smaller sprocket, particularly when shifting to the 11 which is when the chain is most likely to come off.
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Re: Why don't we go with a single chainring for tri? [GTOscott] [ In reply to ]
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GTOscott wrote:
44T chainring and 36T cassette yields a climbing ratio of 1.22 vs a ratio of 1.21 with the prior compact set up of 34T chainring and 28T cassette cog.
44T chainring and 11T cassette yeilds a top speed ratio of 4.00 vs a ratio of 4.55 with the prior compact set up of 50T chainring and 11T cassette cog
When I switch to 46T CX1 Chainring when available:
46T chainring and 36T cassette cog yeilds a climbing ratio of 1.28 (which is more than enough to climb the steep hills around Bloomington, Indiana easily)
46T chainring and 11T cassette cog yeilds a top speed ratio of 4.18 (just 8% less top end than compact 50/11 gearing so should be good for just about everything)


This doesn't work for me for two reasons. A) I can, and do, often spin out a 52x11 gear. B) The jumps between cogs on a 36x11 cassette are way too big for me. Personally I get more out of 52/38 with a 23x11 cassette. I can still climb well, it's harder to spin out and when I do I am going quite a bit faster and I get very tight, compact jumps up and down the cassette.

That said to each their own and I am glad to hear it works for you.

Now on a MTB I completely agree with you :) On a MTB I am never spinning out as I am hanging on for dear life well before that happens and the extra big cogs sure make it easier to climb rocky and rooted routes.

I'll edit this to add it might also be different on the distance of your race. Hammering hard in a sprint or Oly you might need more than the 46x11 but long steady efforts like 70.3 or 140.6 it might be sufficient.


Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca
Last edited by: rbuike: Jun 4, 14 17:25
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Re: Why don't we go with a single chainring for tri? [TriTater] [ In reply to ]
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Pro cyclists tried that with bad results(chain falling off). Very little upside.
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Re: Why don't we go with a single chainring for tri? [rbuike] [ In reply to ]
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rbuike wrote:
This doesn't work for me for two reasons. A) I can, and do, often spin out a 52x11 gear. ...

I can't get beyond those statements! You're 'often' going over 70hm/h (52x11 at 120rpm)? I live in Burlington too. You might hit that on the occasional escarpment descent, for a very short period of time. Often? ...I doubt it.
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Re: Why don't we go with a single chainring for tri? [SuperDave] [ In reply to ]
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What kind of drag numbers do you gain without the FD? I raced on the US PRO TT course (not as part of US PRO) and with a 52-36/11-25 I never needed to go small ring but it was not flat, so what did I give up there?

Strava page
http://www.strava.com/segments/7281305?filter=overall
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Re: Why don't we go with a single chainring for tri? [AaronT] [ In reply to ]
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AaronT wrote:
What kind of drag numbers do you gain without the FD? I raced on the US PRO TT course (not as part of US PRO) and with a 52-36/11-25 I never needed to go small ring but it was not flat, so what did I give up there?

Strava page
http://www.strava.com/segments/7281305?filter=overall

I didn't just take off the FD, there are no shifting components whatsoever. I'd expect 200-370g less drag without these items on an optimally designed "gearless" frame.

-SD

https://www.kickstarter.com/...bike-for-the-new-era
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Re: Why don't we go with a single chainring for tri? [beston] [ In reply to ]
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beston wrote:
rbuike wrote:

This doesn't work for me for two reasons. A) I can, and do, often spin out a 52x11 gear. ...


I can't get beyond those statements! You're 'often' going over 70hm/h (52x11 at 120rpm)? I live in Burlington too. You might hit that on the occasional escarpment descent, for a very short period of time. Often? ...I doubt it.


Racing? Yes. Rev3 Knoxville 3 weeks ago I spent 8 minutes of the 1:07 bike split (Oly) below 20RPM or above 110RPM. I'd say 12% of a bike split is often.

That said the large gaps between cog sizes is the real issue.


Rodney
TrainingPeaks | Altra Running | RAD Roller
http://www.goinglong.ca
Last edited by: rbuike: Jun 5, 14 4:21
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Re: Why don't we go with a single chainring for tri? [rbuike] [ In reply to ]
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rbuike wrote:

Racing? Yes. Rev3 Knoxville 3 weeks ago I spent 8 minutes of the 1:07 bike split (Oly) below 20RPM or above 110RPM. I'd say 12% of a bike split is often.

That said the large gaps between cog sizes is the real issue.

I'll let it go (after this)... If you spent a whole 8 minutes going up and down hills, the majority of that '8 minutes' would have been spent going up hill. Especially with time spent peddling at 20rpm! So no, you were not spending 12% of your race going downhill and spinning out.

I apologize for picking on you. You just caught one of my pet-peeves after a long night of work. I'll stop now;).
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Re: Why don't we go with a single chainring for tri? [beston] [ In reply to ]
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beston wrote:
rbuike wrote:

This doesn't work for me for two reasons. A) I can, and do, often spin out a 52x11 gear. ...


I can't get beyond those statements! You're 'often' going over 70hm/h (52x11 at 120rpm)? I live in Burlington too. You might hit that on the occasional escarpment descent, for a very short period of time. Often? ...I doubt it.

I was thinking the same thing - impossible to "spin out" a 52X11 unless you pedal along at a cadence of 40 and 80 feels like you are spinning out....
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Re: Why don't we go with a single chainring for tri? [endosch2] [ In reply to ]
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I must admit, I ran the numbers and an 11-32 with a 50T chainring would work just fine this weekend at Kansas 70.3. And if you comfortable mashing up the climbs for a minute or so, an 11-28 would work too. On flat courses, you could go to a 12-25 with a 52T chainring. Interesting. Now I'd need a new

However, then there's very hilly courses at IM pace. I guess there's the 11-36 with maybe a 48T, but the gear spacing would get pretty large. But if it's constantly rolling, maybe that's not a big deal. Just a matter of adapting to riding a wider RPM range I suppose.

This is intriguing. Yes I'm the same guy arguing against a compact, but that's just an argument in gear ratio ranges only, in this case there are additional benefits.


Plus you could mess with people. You could simply remove the left shift lever on your extension, but leave the body there... and people would be like "dude, you shifter is broken".... and you could say "oh shit, that's not good. I guess I'll just go without it".


Spining out a 52x11?... what's that 45mph at 105RPM.


TrainingBible Coaching
http://www.trainingbible.com
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