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Old 04-18-05, 01:49 PM   #1
mdk555
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Need some more speed

Howdi

My tandem, the 555 EXPRESS, has amongst others Shimano Ultegra, a 32/44/55 chain ring and 11/12/14/16/18/21/24/28/32 cluster - I find that between 60 and 65km/h on the downhill I no longer have “contact” with the gears and have no option but to use gravity/most aerodynamic position to go faster. This is cool but in Cape Town South Africa many of our hilly/mountain routes that we traverse/race are followed by a long decent or a gentle rolling hill.

I need the easy gears as we have many tough hills/mountains to conquer like “Hellshoogte” (English – Hellish High), “Ou Kaapse Weg” (English – Old Cape Way) and then “Vissershok” – the only to translate this one is besides that Vissershok has a gradient that has broken the spirit of many a cyclist but has a stunning fast down section thru farmlands and vineyards. I rode it on Sunday and only managed a top climbing speed of 8km/h.

My obvious problem is that I would like to get “contact” with the gears on the decent before I have to wait for 60/65km/h to appear on the speedometer which can be very frustrating when in an organized ride/race and there is gentle hill awaiting me where I need the speed to power over it.

Any suggestions?

Cheers,
mdk and the 555 EXPRESS
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Old 04-18-05, 02:03 PM   #2
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So what you are saying is that you spin out a 55/11 and want more gear inches?

Work you your combined spin maybe?

Running a 53/12, I just spin it out, tuck in and enjoy the ride...
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Old 04-18-05, 03:36 PM   #3
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Years ago we were the only male/female tandem duo racing against 4 male/male teams on an 11 mile downhill in Arizona. We spun out our top gear at that time: a 119 inch gear . . . we were bouncing on the saddles at 44 mph . . . a waste of energy! The male/male teams were frustrated that they could not drop us old timers. Went into a deep tuck and hung in!
When your computer reaches a more reasonable speed, resume pedaling again to power up the next hill . . . at least part way!
Most singles cannot keep up with a tandem on steep descents . . . unless they are drafting you.
'Vissershok' translates to me as 'Fisherman . . . ' (?) or something close to that?
Ik ben nu lange weg van Europa, zo Vlaams, Hollands, en SuidAfrikaans is niet te gemakkelijk! Tot ziens!!!

Pedal on TWOgether!
Rudy and Kay/Zonatandem
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Old 04-18-05, 03:43 PM   #4
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Salsa make a 56 ring, I don't think you can get much taller geared than 56/11.
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Old 04-18-05, 04:39 PM   #5
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Quote:
Originally Posted by galen_52657
Work you your combined spin maybe?
What he said.

My GF and I get up to 44 MPH or so with a 53/11 before we have to really concentrate on our spin. IE, this is a fast spin but no bouncing (46 - 47 tops). With a 55/11 at 40 mph you are at only 100 RPM's. Wind that bad boy up!

This said, there are always hills you'll spin out on if you keep your rings in a workable range. Otherwise your big ring will only be good for down hills.
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Old 04-18-05, 05:05 PM   #6
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Quote:
Originally Posted by mdk555
I no longer have “contact” with the gears and have no option but to use gravity/most aerodynamic position to go faster.
Use gravity and the most aerodynamic position; you'll just slow yourself down pushing the cranks. Seriously, if you were spinning out at 120 rpm on the flats, a larger chainring might be necessary but even then you'd probably never reap any benefits from it and end up doing-in your knees.

In other words, the juice ain't worth the squeeze and you'll end up with all kinds of shifting issues if you need to keep a moderate size middle ring and small granny on the bike.
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Old 04-18-05, 08:08 PM   #7
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I figured he had already working around the shifting issues with the 55, and he didn't say anything about wanting to save his knees for old age ;-)
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Old 04-18-05, 10:13 PM   #8
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['Vissershok' translates to me as 'Fisherman . . . ' (?) or something close to that]

'Vissershok' - hok could mean corner or cage and Visser could mean fisherman or it's a surname. Baie dankie vir jou help.
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Old 04-18-05, 10:52 PM   #9
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In Dutch ,"Visser Hoek" would mean 'fisherman corner'. So I think we're close!
The last time I was able to do something with SuidAfrikaans was during the Korean War back in 1952-53 when I got along real well with 2nd SouthAf Fighter Squadron at K-55; was the only GI that became an honorary member of SAAF (the SouthAf Air Force).
The French company, TA, used to make some huge chainrings that may, or may not, fit your crankset. All the way up to 70 teeth! However, no derailleur could handle the spread you'd need to also climb UP the hills!
But a 56T big ring might help.

Pedal on TWOgether!
Rudy and Kay/zonatandem
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Old 04-18-05, 11:51 PM   #10
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Quote:
Originally Posted by zonatandem
The French company, TA, used to make some huge chainrings that may, or may not, fit your crankset. All the way up to 70 teeth! However, no derailleur could handle the spread you'd need to also climb UP the hills! But a 56T big ring might help.
Specialties TA still makes the big chainrings; Peter White stocks both 58t and 60t 130mm Alize chainrings:
http://www.peterwhitecycles.com/chainrings.asp

56t isn't going to do much vs. the 55 that's already on the bike:
55x11 = 133 gear inches or 39.8 mph @ 100 rpm
56x11 = 136 gear inches or 40.5 mph @ 100 rpm
58x11 = 141 gear inches or 42.0 mph @ 100 rpm
60x11 + 146 gear inches or 43.4 mph @ 100 rpm
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Old 04-19-05, 10:56 PM   #11
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TNT used to make a 10 tooth cog. Search around, one might be available. They were made for 7 / 8 speed spacing (the width of the built on spacer).

You'd use a shimano 8 speed rear hub, remove the casette body and replace it with a 7 speed. Then you install 7 cogs (7 or 8 speed shimano cogs both work, plus spacers) onto the casette body, then screw on the 10T which became your eighth cog and functioned as the lockring also.

It's possible that you could do the above described procedure with 8 9 speed cogs on a 7 speed body and have the built on spacer on the 10 toother machined down just a hair to match the spacing of the 9 speed cogs.

Guess you might wanna stick with 9 speed, as reverting to 8 would be pricey. also, you could recombine w/ an 11-34 casette to build 10,11,12,14,17,20,24,28,34 which would give you a slightly lower low as well. heck, you have the triple, you could split shift more to maintain tighter gear jumps.

I don't know if these are still available, i recall someone at a shop in Tucson? AZ finding one for me a few years back. Tha would add a good chunk of gearing, being slightly larger than 60x11, and still allow your front shifting to function reasonably. or you could build yourself a fixed gear bike, set up a low 60's gear inch drive, and join local hammer rides... this'll get your spin up to speed in no time
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Old 04-23-05, 04:07 PM   #12
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Quote:
Originally Posted by mdk555
Howdi

My obvious problem is that I would like to get “contact” with the gears on the decent before I have to wait for 60/65km/h to appear on the speedometer which can be very frustrating when in an organized ride/race and there is gentle hill awaiting me where I need the speed to power over it.

Any suggestions?

Cheers,
mdk and the 555 EXPRESS
Just converted to MPH and 65kph is around 40 mph. I use 48 as My largest gear on the front and 11 as the smallest on my cassette. I ride off road and occasionally do a Road ride. Funny thing is we can attain a higher speed with our 26x2.1 mountain bike knobblies, than we can on 26x1.4 slicks. I did not say that the higher speed on the knobblies is easier, but we cannot get as high a speed with the smaller circumference slicks. Rolling resistance is less on the slicks so I will not be using the knobblies on the road again unless it is to get to our local hills.

It is only a thought, but have you tried using a larger circumference tyre? I know that for top performance a narrower tyre is supposed to work better, but if it is cadence to be got up, a larger circumference tyre may work. The other thought is that if a hill gets so much speed that you cannot catch the pedals, Do get in the tucked position and get up speed. The amount of drag that will be caused at 65kph with legs flayling about must be tremendous.

Being an off roader, I am probably talking out of the back of my neck, but 40 mph sounds quite high to me. (At least for continual pedalling) How many road racers can pedal at this speed- for any length of time? We have time trials on the roads over in the UK, and on a very slight downhill section, I have followed some exceptional club riders, and have yet to see one above 35/6 mph. And as soon as they are on the flat, that speed drops as well as a gear or two.
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Old 04-25-05, 11:09 AM   #13
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Howdi

Thanks for the reply but it’s not the flat road speed that I was referring to, it’s the fact that on the decent from a hill I loose “contact” with the gears at +- 65km/h and then have to rely on gravity/freewheeling for more speed. The frustrating part is that the terrain we cycle on is very hilly – maybe I should expand on hilly.

We would have a gentle climb followed by decent and then immediately another gentle climb. On the decent we can attain speeds of 65km/h + but then before the next climb approaches we have to wait for gravity to slow the tandem down to 60/65km/h before we get “contact” with gears and can power again.

For solo riders this would be called ‘big blade riding” riding where you can speed downhill, stay in “contact” in the big blade and use your momentum to get up and over the hill whist still staying in the big blade. The problem that I am finding is I loose much momentum before I can pedal again on the accent of a hill and maybe this type of terrain calls for a different rear ratio.

Cheers,
mdk and the 555 EXPRESS (Enthusiastic Xtreme Paired Riders Experiencing Simultaneous Speeds)

Last edited by mdk555; 04-25-05 at 01:50 PM.
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Old 04-25-05, 05:42 PM   #14
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I think you need a computer with cadence if you do not already have one. You should be able to hold a steady 115 rpm without much trouble. For sporting riding, I normally shift up at about 110 rpm, but of course I can spin much faster if I need to. It's also not clear what speed you need, but it's likely that some big ring in combination with an 11T cog will do the job in combination with good pedaling skills and high cadence.

I'm old and fat now, but just two years ago I was chasing a tandem that I had allowed a gap, down a moderate slope, pedaling up to 55 mph with a 52 X 12T on my single. A check of their computer later showed they had achieved 56 mph, which probably explains why I did not catch them until they stopped at the bottom....
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Old 04-25-05, 06:00 PM   #15
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Note that your gear range gives 500% difference between low (32:32) and high (55:11). A Rohloff Speedhub gives 527%. If you wanted to get even crazier, a Schlumpf Speed Drive could increase this by a factor of 2.5, for 1317.5% range - all without derailers. There should be a gear in there for all occasions (e.g. from 20" - 260").
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