Numpty IM Bike Thread

A lot depends on you - what events you plan to ride and how strong you are.   There isn't that much difference between a 50 and a 52 - anyone asking about gearing is almost certainly going to be OK with a 50*11 or 50*12.     On the other hand how often are you going to need a 34 ring on a TT bike ?    If it was me I'd stay with a standard double but it's what suits you.

As for 9/10/11 when referring to clinchers - I don't think it refers to anything - are you sure it isn't referring to the freehub on the wheel and what speed cassette it will take ?

39/53.

Could you not put glue in the rims and then refit the existing tubs with the existing tape back on? I thought the idea of putting the tape on for 24 hours was with a clean tub on top to make sure it was pressed tight against the rim, which presumably you cant do as the exisiting tape will make it a bit trickier.

I don't know for definite - the dark art of tub maintenance is beyond me - hence why I stuck with clinchers

When you say tape do you mean the base tape of the tubular tyre or tub tape that was used to fix the tubulars to the rims ?     If your dad means you've peeled the base tape off the tubulars which were fixed with glue then he is probably right.   If you mean you've just removed the old tub tape then you don't have a problem.   

I should add I rarely use tubs so whether you can or should leave old tub tape on I'm not sure - I'd probably remove it if I were retaping them.   

Hi I mean the tub tape that was used to fix the tubulars to the rims.

I figure that with new rims and new tubs you'd have to use new tape so I should be OK. There''s also the fact that i did a lousy job with the old tape as it's definitley not on the middle of the tyre , so I 'd like to re-do it and get it right.

Yes I think I'd have done what you've done - been a while since I taped tubs but like you say it's only the same as new wheels and tyres isn't it.

Can anyone tell me why 53/39 is now standard, rather than 42/52 as was standard in the old days when 8 gears was enough for any drugged up tour rider ?

im also wondering about longer cranks.  but thats for a another day

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??

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 ) 

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

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...

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....

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...

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

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

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.

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