Current Projects chat and miscellany

Lol!

Tbh, I'm not gonna change anything in the near future, unless someone wants to swap 165-167.5mm Omniums for mine.

Its more that I wanted to understand the principles of how it works because it seemed counter intuitive to me, now I think I understand it, it does make more sense and adds to my knowledge of bicycles and the riding of them... I think! ;P

This is making me think I should swap my 170s for 165s as, for a small difference in ride, I would have a larger gain in versatility in terms of where I could actually use the bike. Might be moving to Manchester/Yorkshire in the next year or so and being able to ride the velodrome in Mcr would be nice.

You may get away with 170s at Manchester, I did and I know others have.... Maybe it's luck of the draw.

I would have thought BB drop would play more of a factor?

After all the BB drop on my Omnium was only 40mm, so could get away with 170mm cranks anywhere and not touch ground, whereas, the Mash is 58mm which is why I started the whole convoluted crank length furor... sheepish

From now on I will nerg any and everyone who mentions crank length.

20% of the forum is '...165...' or '...175...'

Hasn't anyone got a shitty conversion with espresso wheels or a WW project or something?!

Crank Length

Its more that I wanted to understand the principles of how it works because it seemed counter intuitive to me, now I think I understand it, it does make more sense and adds to my knowledge of bicycles and the riding of them... I think! ;P

I find this book to be an interesting read to understand the principles of bicycle;

Bicycle Design: The Search for the Perfect Machine Richard's Cycle Books: Amazon.co.uk: Mike Burrows: Books

I'm sure other may have better recommendation, but it's a good start.

Nice one Ed, that goes on my to get list.

The problem I have with this statement is that various people have done supposedly scientific tests and come to a different conclusion to this

I expect we're both looking at the same few research papers and drawing different conclusions from the combined results. The maximal power and metabolic cost results show a pretty flat graph for medium length cranks (a wider range than the 165-180 normally available) which makes me say crank length doesn't matter, while they show some variance at extreme crank lengths (120mm and 220mm) which makes you say crank length matters.

My own n=1 tests show that 10 mile TT time on a fixed course is unchanged if crank length is changed from 175mm to 140mm while keeping gain ratio constant and making no other changes to the bicycle. Obvious weaknesses in those tests include lack of control, lack of proper instrumentation and very different adaptation times for the two lengths tested, i.e. 30 years on 175s vs. a week on 140s. However, the results were so close (just a few seconds) and so out of proportion to the variability caused by changing gain ratio that it didn't seem worth pursuing when there were plenty of more substantial gains to chase.

On TT bikes where hip angle closure can limit the torso angle, some people might find short cranks a benefit, although it seems that most of us can get as low as we need to without resorting to such measures. That's an aerodynamic question rather than a biomechanical one. As I pointed out way up thread, not many people are compromised by hip angle closure when riding a normal road/track bike on the drops.

As I also pointed out, the science is both sparse and, in terms of recent rapid progress in bicycle science, old. However, in the decade since Martin & Spirduso, several very well funded teams have aggressively chased marginal gains, yet we still see all elite competitors using the same narrow range of crank lengths which have been used almost since the introduction of non-unity relation between crank speed and wheel speed, even for athletes of widely ranging size.

Right, genuine thanks to that Mr.Tester and Mr.Fox as its probably been frustrating trying to explain it terms I understand. ;P
I kinda get it enough now to know there's really not much point in bothering my head about it.
If I do get an opportunity to replace mine with 165-167.5mm I might do out of said practicalities, but for now it might be best to leave the subject be, as I think the rest of the forum might lynch us soon.

Mike Burrows' book<

+1

Very readable book that explains the concepts behind bicycle design in bullshit-free language, using proper engineering principles. He does go on a bit about recumbents and other HPVs, but there's lots of interesting reading.

Dat feel when I rode 177.5s for ages because I got them cheap.

So does lowering the saddle 5mm.

Haha! Rinsed!

project ahoy - lots to do but not a bad start

photo.JPG by monomaniac(tom), on Flickr

^Looks sweet, but that saddle-hood drop, letalone saddle-drop, looks pretty big to me.
Lots of weight on the hands, strain on the neck

longggg stem!

So does lowering the saddle 5mm.

Sorry, I ignored this due to irrelevance, was I supposed to retort?

^Looks sweet, but that saddle-hood drop, letalone saddle-drop, looks pretty big to me.
Lots of weight on the hands, strain on the neck

That's hardly any saddle-bar drop for the dedicated Hipster, vide my foray into the field:

Slave mode engaged.

^ Sexy tandem there, NSFW?

Two images of Ryan at Oak Cycle's replacement of my brake bridge and one of the whole bike. Still very happy :)

project ahoy - lots to do but not a bad start

photo.JPG by monomaniac(tom), on Flickr

the saddle will be lower than that and the stem a touch higher once built but generally with my body i tend to run quite a big drop with no problems - this is meant to be fast not comfortable (at least not as comfortable as my brompton which is almost parallel or mercian which drop is only a few inches

photo.jpg by monomaniac(tom), on Flickr

Rixon looks good, you should get internal cable routing next

^dammit, hadn't thought of that but now I have to...more expense!