Those with shortened cranks

[531colin]

If your pelvis rocks when you are on the saddle, your saddle is too high.
Read this https://www.stevehoggbikefitting.com/bikefit/2011/05/addendum-to-seat-height-how-hard-can-it-be-2/

[Dave W]

So do shorter cranks make you faster uphill?

I did another 63miler Sunday. Into wind I found it relatively easy to match df's probably faster. I left the slower group and chased the medium group. On the return leg I struggled to stay in touch downwind and definitely couldn't match the medium group uphill.

One thing I have noticed, every df rider in my club just has to get past, inside, outside, anywhere they just won't have it. They can't draft it either
Reminds me of the time I drove an old Skoda - every one just had to overtake it.

[UpWrong]

Sounds like you are having fun

Shorter cranks encourage and enable better spinning, and spinning is the key to sustained power output. So unless you are brilliant spinner at the moment I would expect an improvement in performance. Why not get a cadence meter and measure the change?

What crankset do you currently have, double or triple, crank length, BB type?

[Dave W]

Tiagra double compact 52 34? Can't remember. 11 - 34 ten speed on the back. 172.5 cranks if I remember correctly. Fair bit of knee pain after a good ride.

[UpWrong]

I suggest the Stronglight Impact Kid crankset from Spa cycles at £42. I have the 150mm set but I suggest you go with the 155mm set. Comes with 44/34 rings, maybe change outer to 48T.

[Dave W]

mmm, sounds a bit low geared. I use every available gear on just about every ride i reckon including the top end.

Don't think the tiagra can be shortened much as it's fluted on the inside for much of it's length, otherwise I would consider that.

[UpWrong]

Remember that you will be pedalling at a higher RPM so you can afford to lower the gearing a little. The problem with a compact chainset is that the smallest ring that will fit is a 33 which is only one less than the 34T you currently have.

[531colin]

Remember that you will be pedalling at a higher RPM so you can afford to lower the gearing a little. The problem with a compact chainset is that the smallest ring that will fit is a 33 which is only one less than the 34T you currently have.

looked at in another way........
....for the same foot speed you will get a higher cadence with a shorter crank.

[531colin]

Had an interesting day yesterday, riding from York to Scarborough on a borrowed Brompton with flat pedals.
Very short reach compared to my drop bar bikes I'm used to, so that i was sat bolt upright.
With the wind largely favourable, it was fine on the level, but as soon as the road went up, i was in trouble. I know that on my own bikes I slide back on the saddle, work the bars and pull the pedal back at the bottom and forward at the top using the cleats......what i didn't know was how much of the time i do it!
If you have never ridden a Brompton, it might help to know that if you try to work the bars you can feel them flex quite alarmingly.....and i couldn't get out of the saddle and steer anything like a straight course; there may be people who can do that on a Brompton, but it isn't me!
The gearing wasn't low enough so that i could sit and spin up anything remotely steep, and I ended up walking a couple of stretches on what is (for Yorkshire) a "flat" route.
For a bike that you can fold up and put two of them on a shelf in the train thats meant for a suitcase, its remarkable......as a bike to use for a day ride the riding position and the associated rider ergonomics are seriously compromised.
Is this the same as the recumbent vs. upright discussion?

[Geoff.D]

For a bike that you can fold up and put two of them on a shelf in the train thats meant for a suitcase, its remarkable......as a bike to use for a day ride the riding position and the associated rider ergonomics are seriously compromised.
Is this the same as the recumbent vs. upright discussion?

Well.......yes and no. It's the same discussion in that you'ved recognised that they're designed for two quite different applications and compared the rider ergonomics, focussing particularly for hill climbing.

But, it's not the same in that the the rider ergonomics in the recumbent/upright discussion are so far different that it's not possible to use the phrase "...are seriously compromised". This phrase champions the traditional df position as the optimum. But, it's only so for particular applications in an upright bike. It could just as easily be said (in terms of comfort during the whole of your hypothetical day ride, say) that "........the df ergonomics are seriously compromised".

I ride a 'bent bike, a 'bent trike, a semi-recumbent tandem and a Brommie. For me, the trike is my favourite and all the others are "compromises". But, this is unfair to the others. The trike also has compromises when compared to the advantages of the Brommie, for example.

[[XAP]Bob]

DF ergonomics are a serious compromise.
For what other activity do we put so much weight on such a small area?

I. Ightngo and play with some varied crank lengths this weekend...

[531colin]

OK......read....."the riding position and the rider ergonomics for power output are seriously compromised"

Better?

DF ergonomics are a serious compromise.
For what other activity do we put so much weight on such a small area?.............

well, speaking personally, i don't put that much weight on my bum on my own uprights.
I think that the 2 "new cyclists" who currently have threads on the forum about their sore backsides probably do put a lot of weight on their backsides, but many years ago i learned to "ride" the thing....with my backside "kissing the saddle".....if you sit on the saddle like a sack of spuds, then you will get sore.
For example, the ride I did on the Brommie was only about 50 miles, and it felt like I had been sitting on a saddle all day. On my own bikes i can do more than that mileage day after day touring with no discomfort at all. The upright position of the borrowed Brommie meant I didn't have the ability to distribute my weight as i do on a bike properly set up for long rides.

[531colin]

.............
But, it's not the same in that the the rider ergonomics in the recumbent/upright discussion are so far different that it's not possible to use the phrase "...are seriously compromised". This phrase champions the traditional df position as the optimum. But, it's only so for particular applications in an upright bike. It could just as easily be said (in terms of comfort during the whole of your hypothetical day ride, say) that "........the df ergonomics are seriously compromised".

I ride a 'bent bike, a 'bent trike, a semi-recumbent tandem and a Brommie. For me, the trike is my favourite and all the others are "compromises". But, this is unfair to the others. The trike also has compromises when compared to the advantages of the Brommie, for example.

Two negatives in that sentence.....

You accuse me of "championing" the traditional D/F position as the optimum.......i hope that I have clarified that I meant the optimum for power output, which is what this thread is about.
i note that you don't currently ride an upright with what i would consider to be a suitable riding position for an all- day ride.

[531colin]

Let me tell you where i am with all this.
I'm most unlikely to ever get a bent, for lots of reasons....
I like to look over the hedge, I like to ride tracks
I like to put a couple of bikes in the car, or a handful of bikes on the train, or a dozen bikes on the minibus trailer, and take off with some mates.
i don't have the storage.

If you have decided bents are for you, thats great, happy days.
If i question something, its simply curiosity. I'm interested in the interaction of man and machine. I'm not laughing at you, or saying you are wrong.

however, intellectual curiosity has its limits.....you lot blindly saying you are right is getting wearing.

[[XAP]Bob]

Sarcasm over text clearly not working...

Every position is a serious compromise - because compromises are the basis of all engineering...

I would agree that the DF is better for instant power output - over longer time periods the CV system is the limit, and instant high power is not necessarily required, or even desired.


It's interesting that crank length is almost fixed on DF bikes, irrespective of frame size...