Numpty IM Bike Thread

Bike ponces only welcome if they don't speak in tongues

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09/10/2012 at 12:27

no idea why the change but a 53*39 with 10 at the back gives a good spread.   many now use a compact with a 50*34 or 36, that allows better gearing for climbing but at the expense of top end speed.  for weaker or heavier riders, this is a good compromise.

why longer cranks??

09/10/2012 at 13:59

loner cranks - better leverage - something to do with the length of your leg parts - the longer crank makes easier to turn a bigger gear. i think

so 52/42 with 12-23 ( 12-13-14-15-17-19-21-23 ) should be fine then. for outlaw that is.

(assuming ive put the miles into the legs of course )

53/39 with 10 at the back means too much choice.....imho ( not that its worth tuppence ) 

 

09/10/2012 at 14:25

crank lengths = science vs reality!  there's no easy solution based on leverage and body dimensions as it can also depend on your riding style - some like to gring the gears; others prefer to spin.  and to an extent, the bike will also help define what's best.   some interesting techy stuff here - http://bikedynamics.co.uk/FitGuidecranks.htm

perhaps a full bike fitting is the best way to define correct crank length for you and your rig

in reality, most choose something appropriate and get on with and 2.5mm here or there will make little difference to Mr Average

TheEngineer    pirate
09/10/2012 at 14:31

Quite possibly sticking my head above the parapet here but...

If you can use 53x11 for anything more sustained than spinning out downhill, you're in the top few percent of cyclists in the world. On a 700x23c, this is roughly 126.53 gear inches. (For those who don't speak in tongues... the bigger this number, the harder it is to push.) 

For a sustained effort such as an IM, the best context is probably the hour record. Chris Boardman only pushed 56x13, equating to 113.1", and nobody setting the record has exceeded 113.8" (Obree in Hamar).

Most people just won't get enough USEFUL work out of big gears IMO, whether on a road bike (compact offers a better range for most when climbing) or a TT (think you can push an 11 all day? I'll bet my entry fee you can't!). Mostly it just seems to be d*ck-measuring.

Sur la plaque, ladies and gents...

Edited: 09/10/2012 at 14:33
09/10/2012 at 14:44

I have 53x11 on my race bike - I have spun it out on a downhill a number of times but then I tend not to hang around...   working that gear on the flat is another thing altogether unless there's a strong tailwind and even then it takes it out of your legs very quickly.   but it's nice to have for those times when you can benefit from it....

TheEngineer    pirate
09/10/2012 at 15:20

The only time it can really be justified is long non-technical descents - if you can push a bigger gear before you spin out, you'll hit terminal velocity sooner and save time. If however, you end up scrubbing that speed off because there's corners, then you're not saving much time at all. Better to have the choice for going back up the other side...

09/10/2012 at 15:31

"Better to have the choice for going back up the other side..."

that's called a triple.......

 

Bouncing Barlist    pirate
09/10/2012 at 15:32

Im with the camp that thinks there is no reason to have anything other than a compact unless youre a top cyclist.  When spinning out on a 53 x 11 downhill youre expending exponentially more energy pushing wind the faster you go.  My view is that once you get upwards of 40mph (or a certain number of wattts) youre better saving the energy for the next hill.

Being a fatty my personal tactic is to pedal like fury at the top part of the hill and carry the speed on the decent by just freewheeling, other than occasionally turning the legs over there pedaling harder makes only a marginal difference to my speed.

Edited: 09/10/2012 at 15:33
TheEngineer    pirate
09/10/2012 at 15:57
fat buddha wrote (see)

"Better to have the choice for going back up the other side..."

that's called a triple.......

 

Only if you're not ashamed of using the granny gear. Otherwise it's a poorly spread compromise between a double and a compact!

Rule 47

Edited: 09/10/2012 at 15:59
09/10/2012 at 16:13

I've gone over to 50/36 compact mainly for when I rode the Marmotte event in the Alps and the 36 was just that little bit more useful than a 39  - while the 50 big ring is still big enough paired with a 12 up cassette.   That said people that really hammer down 50mph descents would find a 53*11 useful - I tend to stop pedalling and start praying once I get to mid 40s.    

Because my compact is Campag Record and it replaced a Centaur double I've just left it on and use a 12-23 for racing/everyday riding and then stick a bigger cassette on if I'm going to the Alps or I suppose I'd do the same for the Lakes, Dales etc.

I've got a double on the winter bike though and it's fine in the Peak District - I think with 10 and 11 speed now you get such a range at the back that apart from real extreme climbs or descents a compact OR a double can give you all the range you need - certainly for the Outlaw you could probably do it on a single ring - maybe even a single gear !  

TheEngineer    pirate
09/10/2012 at 16:24
popsider wrote (see)

Next year I'm going to ride the Outlaw on a singlespeed.

cougie    pirate
09/10/2012 at 16:33


I was going to ride it fixed wheel for a bet with Bassy but you're not allowed fixed.
Singlespeed is very doable pops
09/10/2012 at 16:59
TheEngineer wrote (see)
fat buddha wrote (see)

"Better to have the choice for going back up the other side..."

that's called a triple.......

 

Only if you're not ashamed of using the granny gear. Otherwise it's a poorly spread compromise between a double and a compact!

Rule 47

not ashamed to use granny - it often gets my bulk up a hill quicker than some fool grinding to a stuttering halt on a double...anyway - rules are there to be broken.....

09/10/2012 at 17:04

whats with all the 23' tyres. my racer has 19's on it. i thought 23's were for cyclo-cross and mtb'rs?

so much of this bike stuff is effective at the 1% for athelets and effective on the bottom line for the vendor when the mislead masses get on board.

...if your already fast enough for a disc wheel - you have a sponsor ready to supply one free.....

09/10/2012 at 17:05

I would suggest that this is the gearing for Outlaw - http://www.sram.com/sram/mountain/family/xx1

OK it's MTB specific but one ring up front and 11 at the back - get the ratios sorted and you'd just have one change to worry about.  or maybe a 3 speed Sturmey Archer??  I did the last 30 miles or so of Outlaw with 3 gears as my rear shifter stopped working - all I had was the front 3 rings to change with.  it didn't bother me that much as I still came in in 6hrs after a few stops to try to fix the problem.

09/10/2012 at 17:12

SL - methinks you mean mm, not feet!  

19mm are usually tubs, 23mm are usually clinchers (extra width for the tubes I think)

CX and MTB tyres are usually clinchers and wider still - 32/35mm for CX and MTB gets measured in inches oddly - 1.9 is usually the thinnest but many run 2.1/2.3 these days

Edited: 09/10/2012 at 17:13
09/10/2012 at 18:11

I started off with 19mm tubulars and a 53*42 7 speed and (I think )  a 13-19 straight through screw on block.   This wasn't 30 years ago either - more like 10 - the bike was older though - nice steel 24" Mercian in 531c  - it seemed fine at the time.   

09/10/2012 at 20:14

Pops I've got a mid to late 80's Billy Whitcomb built Soens 531c frame that upto 2001 had taken me to a 22.29 10 and a 58.30ish 25 and doubled up for road racing by taking the clip on aero bars off!! It's a classic frame probably as your is and one day I'll take it off the turbo ( thats all it does now ) and have it sprayed up nice and get the chroming re-done and try and get it back into it's real era. Never gone wrong though.

IronCat5    pirate
09/10/2012 at 20:47
popsider wrote (see)

I started off with 19mm tubulars and a 53*42 7 speed and (I think )  a 13-19 straight through screw on block.   This wasn't 30 years ago either - more like 10 - the bike was older though - nice steel 24" Mercian in 531c  - it seemed fine at the time.   

My road bike came with similar gearing on a 7 speed block. Only the frame is left now from the £65 ebay purchase.

cougie    pirate
09/10/2012 at 21:50
I used to have narrow tyres but you can corner better on 23s - they're more rounded - the narrow tyres almost have a square profile. Plus you've a bigger cushion of air in the tyre. We've some massive potholes round here after all the rain - I'm quite looking forwards to getting out the winter bike with really chunky tyres on !
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