Author Topic: Gearing  (Read 3529 times)

simonp

  • Omnomnomnipotent.
Gearing
« on: February 27, 2019, 02:38:34 pm »
I went out on my PBP bike on Sunday for a couple of hours and quickly came to the conclusion that I don't like its gearing for flat-ish routes. I had assumed I wanted the widest possible ratios but what's resulted is a large overlap between big and small chainrings combined with a large jump in ratios in the mid-range at typical Audax pace.

The gearing was 50/34 compact double with an 11-30 cassette. I've ordered a new rear cassette, 12-25, so that I have a higher bottom gear, less overlap, more usable gears, and smaller steps in the middle of the range.

Before:

http://www.gear-calculator.com/?GR=DERS&KB=34,50&RZ=11,12,13,14,15,17,19,21,24,27,30&UF=2150&TF=90&SL=2.6&UN=KMH&DV=speed

After:

http://www.gear-calculator.com/?GR=DERS&KB=34,50&RZ=12,13,14,15,16,17,18,19,21,23,25&UF=2150&TF=90&SL=2.6&UN=KMH&DV=speed

In the first setup the big issue is around the 20-25kph speed range. At 90rpm you go 20.8kph, then 23.2kph, then 26.3kph.

With the second set-up it's 20.8, 21.9, 23.2, 24.7, 26.3.

I hope to try the new ratios this weekend. I might find that on hilly routes I miss the 27 and 30 sprockets.

LittleWheelsandBig

  • Whimsy Rider
Re: Gearing
« Reply #1 on: February 27, 2019, 02:59:44 pm »
I find that rolling routes require quite a lot of overlap between chainrings for a comfortable ride, so that I can stay on one chainring for a decent length of time. It can be annoying to keep having to swap rings and double shift at the back for short distances and then back again. Fixed riders don't have so many of these problems.


That said, the gearing you've chosen should be more than enough for PBP for you.
Wheel meet again, don't know where, don't know when...

simonp

  • Omnomnomnipotent.
Re: Gearing
« Reply #2 on: February 27, 2019, 03:15:23 pm »
The overlap of usable gears is from about 25-30kph after; 21-33kph before. However the bike's got Di2 and the synchro-shift makes it much easier to switch seamlessly through the sequence. With the new set-up it's now single-tooth steps on the rear all the way from 21-48kph. With the old arrangement many steps in that range are 2-tooth.

I'll need to check the synchro-shift settings and might customise them a little to avoid hunting between big and little rings at the overlap.

Zed43

  • prefers UK hills over Dutch mountains
Re: Gearing
« Reply #3 on: February 27, 2019, 03:50:15 pm »
So far my preferred setup is a 14-32 cassette with 33/41 chainrings (110BCD), this gives nicely spaced (~ 6%) changes around my cruising speed of 25kph. Ideally I would have 25/29/34 at the end of the cassette instead of 25/28/32 but :shrug:

gear calculator

I intend to set up synchro shifting to move to the small chainring when downshifting when I'm on the 20t cog (and back when upshifting from 17t).

Re: Gearing
« Reply #4 on: February 27, 2019, 04:16:57 pm »
I have fonud 34x25 low enough for wessex events, welsh events and dare i say it mr corless events.
For pbp i wouldn't expect to get out of the big ring-46t , or less i use a different bike. Then the big ring could be 50 or 53!

zigzag

  • unfuckwithable
Re: Gearing
« Reply #5 on: February 27, 2019, 04:59:11 pm »
i've used 52/42 with 12-27 cassette last time and was happy. gears is not a major consideration for pbp, most setups will work fine (as long as they work properly).

Re: Gearing
« Reply #6 on: February 27, 2019, 05:02:03 pm »
46 X 32 with 13 - 26 (13;14;15;16;17;18;19;21;23;26)
I work on the principle if I am revving out on 46 X 13 I should be freewheeling and if I cant manage an accent on 32 X 26 I should be walking.  Not too proud to do either!

It still puzzles me why anyone in our game (or any non professional) would want the ubiquitous 11 sprocket that the big manufactures try to trust upon us!

But, I know it is all personal....my everything else bike is 48 X 20 in the winter months and 48 X 19 in the summer....fixed wheel of course.  :)

Re: Gearing
« Reply #7 on: February 27, 2019, 05:55:52 pm »
I shall probably be using a 13-26 with a 48-38-26 triple.  But I doubt I'll use the small ring.

Re: Gearing
« Reply #8 on: February 27, 2019, 05:56:37 pm »
I'll settle for a triple again (as usual). I do prefer some big gears for descending though.
So quite likely the following set up: 30-40-50 front and 12-27 rear (10 speed).

Re: Gearing
« Reply #9 on: February 27, 2019, 06:59:06 pm »
I shall probably be using a 13-26 with a 48-38-26 triple.  But I doubt I'll use the small ring.

Not the lovely titanium fixed bike this time Ian?

Re: Gearing
« Reply #10 on: February 27, 2019, 07:14:42 pm »
I have fonud 34x25 low enough for wessex events, welsh events and dare i say it mr corless events.
For pbp i wouldn't expect to get out of the big ring-46t , or less i use a different bike. Then the big ring could be 50 or 53!

My legs clearly aren't as strong as postie's because even a 34 x 32 wasn't low enough for me on the steepest climbs of the Mille Pennine last year!

I still have 50/34 and a very worn out 11-32 on one Roubaix and 50/34 with brand new 11-25 on the other, both 10 speed. For PBP I'll go in between with 50/34 and 11-28. It means I can use the shorter cage rear derailleur and should still be able to stay on the big ring virtually all of the time, whilst keeping the 34 ring as an insurance policy for the odd steep ramp and when I'm feeling tired.

On the Shimano 105 10 speed it's only the last two sprockets that are different between the 11-25 and 11-28. They both go 11,12,13,14,15,17,19,21 then 23,25 or 24,28 so the percentage differences are still very good throughout the range and the extra weight is negligible.

I still like my 11 sprocket for those long slightly downhill sections, especially with a tailwind. I don't like pedalling any faster than necessary!


Re: Gearing
« Reply #11 on: February 27, 2019, 08:36:24 pm »
I can guarantee that no-one else has ever used the gearing I used in 1999. Oddities included a Campagnolo Gran Sport front mech, Sun Tour Accushift rear mech, with Shimano RSX 7 speed STIs. The cassette was 14/28. using a TA locknut sprocket. The chainset was a 182.5 mm Stronglight 107, with 56/42 rings.

2003 was a 180mm Sugino MTB chainset, with 22/32/42 rings and an 11 to 19 8-speed cassette. Shimano XT mechs, with right hand Shimano RSX STI, and a left hand Campag Ergo

2007 was a 175mm Shimano Tiagra 50/34 compact and a 13 to 30 8 speed cassette. Shimano XT mechs, with right hand Shimano RSX STI, and a left hand Campag Ergo

2011 was a 175mm 50/40/30 triple, with a 12 to 27 10 speed cassette. Disappointingly, it was all Shimano 105.

Re: Gearing
« Reply #12 on: February 27, 2019, 09:12:42 pm »
My gearing's way above that; for PBP I ran 53/39 with either an 11-23 or 11-25 cassette. Only on the biggest couple of hills was it a struggle, although the audax bike's 18kg fully kitted.

My LEL it was on a more sensible 52/36 with an 11-28 cassette. On Yad Moss and a couple of other places a 11-30 may have been better but I like the 'bling' Dura-Ace 7800 rear derailleur that's fitted.

wilkyboy

  • "nick" by any other name
    • 16-inch wheels
Re: Gearing
« Reply #13 on: February 27, 2019, 09:21:57 pm »
...my everything else bike is 48 X 20 in the winter months and 48 X 19 in the summer....fixed wheel of course.  :)

I'm trying to get my legs used to 48x17 at the moment with a view to running 18 or 19 on the other side for PBP.  Mixed results so far — less spinny than I'm used to and I don't have the proper strength for the gear yet, but I can ride 200 miles on it without dying  ::-)
RRTY #6 done; #7 aborted and restarted.

simonp

  • Omnomnomnipotent.
Re: Gearing
« Reply #14 on: February 27, 2019, 09:28:18 pm »
I have fonud 34x25 low enough for wessex events, welsh events and dare i say it mr corless events.
For pbp i wouldn't expect to get out of the big ring-46t , or less i use a different bike. Then the big ring could be 50 or 53!

47x19 is low enough for PBP.

Re: Gearing
« Reply #15 on: February 27, 2019, 09:52:13 pm »
I did LEL on 40x11-36 (11 speed) and found the gear range fine. I’ll likely do the same for PBP.

I intend to set up synchro shifting to move to the small chainring when downshifting when I'm on the 20t cog (and back when upshifting from 17t).

Last I checked synchro shifting only let’s you pick which *standard* complements you have and it chooses the shifting strategy for you. Setting it up with non-standard chainrings may require some experimentation.

Re: Gearing
« Reply #16 on: February 27, 2019, 10:02:10 pm »
I shall probably be using a 13-26 with a 48-38-26 triple.  But I doubt I'll use the small ring.

Not the lovely titanium fixed bike this time Ian?

I'm taking it easy now I'm an OAP.

quixoticgeek

  • Mostly Harmless
Re: Gearing
« Reply #17 on: February 27, 2019, 10:25:59 pm »
So far my preferred setup is a 14-32 cassette with 33/41 chainrings (110BCD), this gives nicely spaced (~ 6%) changes around my cruising speed of 25kph. Ideally I would have 25/29/34 at the end of the cassette instead of 25/28/32 but :shrug:

gear calculator

I intend to set up synchro shifting to move to the small chainring when downshifting when I'm on the 20t cog (and back when upshifting from 17t).

Are you making the 14-32 from a shimano Junior 14-28, mixed with an 11-32 ? If so why not mix with an 11-34, and get the lower low end?

What 41/33 chainset are you using?

It still puzzles me why anyone in our game (or any non professional) would want the ubiquitous 11 sprocket that the big manufactures try to trust upon us!

It depends. If you have a 50/34, or 59/39, etc... then that 50x11 gear gives you 52kph at 90rpm, but if you have a 46 front ring, then the 11t is only 47.8kph, a 40t gives you only 41.6kph. For many that's too low a top speed. Why run such a small large chain ring? because with modern derailleurs, the max size difference is limited to 16t (10t on mtb), so if you want to have a small enough low gear to spin up hills, you need a small enough little ring. This means that for many, an 11t smallest sprocket is actually entirely sensible, it's the crazy 50/34 chainsets rather than 46/30 that is the issue. But I've had this rant before... a few times...

J

--
Beer, bikes, and backpacking
http://b.42q.eu/

Zed43

  • prefers UK hills over Dutch mountains
Re: Gearing
« Reply #18 on: February 28, 2019, 10:41:16 am »
Indeed combining the junior 14-28 with a 11-32. The (ultegra and 105) 11-34 have the last three cogs on a spider (27+30+34) so that would make a mid section of 19-21-24 (27+30+34) instead of 19-20-22-25-28-32. This would actually work out nicely. Assuming Ultegra Di2 does allow the use of the 3rd cog when on the small ring (XT Di2 does not), and you can find a 24t cog.

At this moment I am still using 34/42t (TA Zephyr) rings, but already got myself some WickWërks junior 33/41 rings when they were on discount  :)

CrazyEnglishTriathlete

  • Miles eaten don't satisfy hunger
  • 3x Brimstone ancien 3x Pendle/Tan Hill DNF
    • CET Ride Reports and Blogs
Re: Gearing
« Reply #19 on: February 28, 2019, 11:52:39 am »
I rode 2007, 2011, and 2015 on triples, 50-40-30 with varying combinations of 12 - 25, 11 - 28 or something similar on the back.  I don't recall ever having to use the little chainring.   It is rolling terrain, and so the jump between chainrings on a compact chainset (e.g. dropping from 50 - 34) will have a bigger impact than on a more dramatically hilly route.  If I was riding it on two chainrings I'd go for my current set up of 50 -36 and 11 - 28.
Eddington Numbers 123 (imperial), 168 (metric) 516 (furlongs)  110 (nautical miles)

Re: Gearing
« Reply #20 on: February 28, 2019, 01:36:55 pm »
I have used the following ratios in the past:

In 1999 - Ultegra 9 spedd triple with something on the back I cannot remember!
In 2003 - 53/39 with 12-25 (Ultegra 9-speed)
In 2007 & 2011 - 50/36 with 12-25 (Campag Record 10 speed)
in 2015 - 52/36 with 12-25 (Campag Record 11 speed)

The rolling terrain lends itself to close-ratio gears; not many steep gradients at all.

Zed43

  • prefers UK hills over Dutch mountains
Re: Gearing
« Reply #21 on: February 28, 2019, 01:57:59 pm »
Slightly off-topic, but how are the hills in PBP? Say compared to the Howardian Hills, Yad Moss and the northern bits of LEL? (yes, I can look at the elevation profile, but for those of you who have done both, what are your subjective impressions?)

Re: Gearing
« Reply #22 on: February 28, 2019, 02:09:50 pm »
Slightly off-topic, but how are the hills in PBP? Say compared to the Howardian Hills, Yad Moss and the northern bits of LEL? (yes, I can look at the elevation profile, but for those of you who have done both, what are your subjective impressions?)
Much easier than any of these. PBP is largely long gradual ascents and descents, though there are a few short steep ones, particulrly at the Paris end (though the change of start/finish may have changed this). I don't know of anywhere in the UK which is directly comparable, maybe Oxfordshire/Warwickshire is closest. Anyway, don't worry about them, they aren't difficult.

Getting back to gearing, I'd just use whatever you have on the bike and are comfortable with. The challenge is the distance, not the gradients.

wilkyboy

  • "nick" by any other name
    • 16-inch wheels
Re: Gearing
« Reply #23 on: February 28, 2019, 03:30:39 pm »
Slightly off-topic, but how are the hills in PBP? Say compared to the Howardian Hills, Yad Moss and the northern bits of LEL? (yes, I can look at the elevation profile, but for those of you who have done both, what are your subjective impressions?)
Much easier than any of these. PBP is largely long gradual ascents and descents, though there are a few short steep ones, particulrly at the Paris end (though the change of start/finish may have changed this). I don't know of anywhere in the UK which is directly comparable, maybe Oxfordshire/Warwickshire is closest. Anyway, don't worry about them, they aren't difficult.

Getting back to gearing, I'd just use whatever you have on the bike and are comfortable with. The challenge is the distance, not the gradients.

The three toughest climbs, from memory, were the steep grade up to the centre of Brest, which is on the route again; the long ascent back to Mortagne-au-Perche, which just seemed to get steeper and steeper, and went on forever after 1000km, which is on the route again; and the climb back through the forest to Paris, which is NOT on the route this year.  None of the three required "mountain" gears and the first and last could be walked in under five minutes if you really had no legs left.

And Yad Moss from either side is a much tougher prospect than Le Roc.

Really it's the constant rolling that's hardest — for most of the ride you're either going up or going down, there's not a lot of flat for most of it, IIRC.
RRTY #6 done; #7 aborted and restarted.

Re: Gearing
« Reply #24 on: February 28, 2019, 04:01:42 pm »
This is the climb through the woods that you won't be doing. A picture from an article by the assistant editor of Cycling Plus. My mate David Robinson and I supplied the photos. This is one of Dave's
https://www.cyclingplus.com/articles/i-rode-it-paul-robson-at-the-2015-paris-brest-paris-randonee/




We met Paul at Loudeac, where he asked us if we could do some stills.
https://www.youtube.com/watch?v=JJwcKk6-lmQ