Tech help please: cranks, cassettes and all that biz

simon

Speeding Up
Jul 19, 2006
96
0
26
Tokyo
#1
Hi Guys,
I got my first road bike last year, it came with a 50-34 crank and 11-25 cassette.
I'm thinking to change the cassette, too many holes. Or even the crank.
Anyway, answers to the questions below would be super helpful.

It should be noted that I'm a theorist, i.e. the decisions I make about my bike setup are done with (otaku style) calculations. I don't actually climb... but hope to one day, soon! :)
Hence, as you guys actually do climb (I keep up with the threads), your help is critical! ;)

A) It looks like my 50-34 compact crank has 19 usable gears. That is, when using the 34 and 11, it seems that my chain runs against the inside of the 50 chainring.
Questions:
With a 52 or 53 and 39 crank, do you actually get 20 usable gears?
In particular, can you use the 39 with the smallest gear in the cassette?
And, is it expected that the front derailleur and or chain angle prevents us from being able to use all 20 gears? Or not?

B) Could some of you guys let me know what crank and cassette combinations you use for the climbs you have been doing recently? And do any of you actually swap cassettes for hills, TT, etc.?

Cheers!
Simon

Ps. If and when I do make it to one of the TCC rides, I'll be the one eyeing up everyone's setup :ninja:
 

trad

Maximum Pace
Dec 4, 2006
393
30
48
Tokyo
#2
Compact vs traditional crank is one of those age old questions. Recommend searching bikeforums or roadbikereview.... there's a ton of otaku type calculations and write-ups on this topic. Having ridden both.. my thoughts are the following:

1. In terms of # of usable gears, I think both are same (basic geometry and cross chain dynamics don't change much)
2. Gear heads have calculated that range of gears for compact have equivalent and potential wider range than traditional crank (since the cassette goes to 11 teeth)
3. Many find that shifting for uphills is a bit of a pain for compacts, since it requires shifting front chain ring and 2-3 gears in the rear at the same time.
4. All things considered, I'll stay with compact or go with triple. I'm old and need a bailout set up.
5. My ideal ideal set up will be 50/36 up front and 11-25 in the rear.
 

simon

Speeding Up
Jul 19, 2006
96
0
26
Tokyo
#3
Thanks for your help.

I have read a bit on the Internet and done more calculations than you can poke a stick at :) But will take a look at the sites you mentioned. Cheers!

I'm happy with the conclusions I have made...
But the (final :confused:) information I need is the actual number of usable gears for the various cranks.

I wondered if the 50-34 was different (less?) than the 53-39 and even 50-36, because of the larger relative difference in chain ring sizes.

Thanks again.
 
Jan 14, 2007
2,516
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Noda
japanichiban.com
#5
I have 3 cassettes and if I'm worried about a hill climb I put my 12-27 on the back. My regular training wheels are 12-25. My race form 11-23 has been used in the hills but only for training purposes. Not being a climber...(yet-[let's hope for reincarnation]).
Whatever cassette I have on the back I try and keep the chain as straight as possible.... small on the front and small on the back is not good for anything...same with big on front big on back.....there are better combinations than going for the angled chain.... Not hard to flick big to small at the front and shift 3 at the back at the same time...:warau:
I try and concentrate on 100rpm cadence at the desired speed and not worry what gear I'm in...if I'm keeping my heart rate under control and maintaining speed and cadence then as far as I'm concerned I'm in the right gear. (hard to do this on steep hills)....but that's when you're usually in the easiest gear and just trying to get the next rev in....

Let the experts have their say....I need to learn...

BTW. I'm not a fan of compacts or triples...maybe in a few years or if my weight increases.... (down 5 kg in the last 2 months)....
 

simon

Speeding Up
Jul 19, 2006
96
0
26
Tokyo
#6
Thanks again guys!
After months of calculations (mostly for fun), I'm near the end:D

So, 20 gears doesn't seem ideal/reasonable... I was still searching now, came across chain inefficiencies or something, but no details.

> there are better combinations than going for the angled chain

Cool. Thanks. Got it. i.e. I'll use this in future calculations and considerations. But...

Edoga.., I'm assuming you have a 53(or 52)/39. Could I ask you this:pray:... it would save me from more hair loss... "Can" you use your 39+12 (with the 12-25)?

> then as far as I'm concerned I'm in the right gear.

I hear you!
But, at the moment, with this 50-34 and 11-25, that right gear is missing (on my individual TT;)).
So I'm going to put a 12-25 or 12-23 in instead... That's why I was asking what's needed to climb with you guys ;)
i.e. 50+23 is a tad higher (easier?) than 53+25, so if most the time you guys don't require that 27, then I'll be cool with the 23:D
... Did I mention I was a theorist?

I have concluded this, for what it's worth.
A compact _can_ give you a wider range of gears, but with larger steps, more holes, or holes in different places. Changing the cassette can fix this, but then your back at what a, for e.g., 53-39 + 12-25 gives. My final conclusion is that, pretty much the same can be achieved with both the 53/39 and 50/34, but the crossover point differs, and that could be more or less annoying, depending on what speed your riding at.

> down 5 kg in the last 2 months

Good going!
Did you change anything with your training or eating?

Thanks again.
 
Jan 14, 2007
2,516
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Noda
japanichiban.com
#7
If I can't find the right gear without getting the chain at a ridiculous angle then I figure I'm out of shape and it's not the bike's fault. What feels good is about as far as I go in gear selection...

Weight loss. I've been at it a long time and I think it's a hereditary war... I lose weight easily in Spring and to boost it all along I've been having lots of lemon juice in the morning for the last 2 or 3 weeks (no breakfast).... I only eat lunch if I've been riding that morning already and I have a normal dinner. The lemons seem to be doing the trick. I have also upped the cardio 100% at the gym 3 to 4 days a week. 30 minutes warm up on the bike and 30 minutes cool down on the bike...200kcals each...and weights in between at a fast pace too.

back to gears again...as my fitness changes throughout the year and depending on conditons (wind etc) I just concentrate on cadence and speed.
I make sure to keep the chain as straight as possible. When I'm in the hills I probably use a gear selection tha is too easy...

The only way to figure out your own personal combo is to spend a lot of time on hills looking at your gears and watching how well you go. I got stuck in a TT at Mt. Tsukuba once...I took my hill climbing wheels and they were in the car. I was warming up on my sprinter 11-23s...the start time was brought forward and I didn't have time to change the wheels. I actually did quite well pushing 23 instead of 27.... mind over matter...don't worry too much about the gears...it's not a physics experiment. :rolleyes:

I actually think the 11 on my 11-23 is a waste of money now...I do hope to use it in a 60+kph sprint oneday but not sure if I'll get there....(have hit 59.9kph with it by myself on the flat). I also had my cadence at 128rpm at the finish line but was only doing 52kph...was no time to calculate what gear I should be in when your heart is at max...(that was slightly uphill too).

I'm still going to stick with the gear that is at the right cadence and speed and fairly straight driving energy forward not side to side is the best gear combination...and I don't care which of the 11, 20-23,27 cog that is at the time....In a race I'm on 52 at the front for the whole race.....If I'm training I'm on 39 at the front. ( I don7t do many hill races as you may have guessed) So I'll let those guys give a better opinion than me.... I tend to crap on too much... :D
 

xtrca

Cruising
Dec 5, 2007
37
1
18
montreal
#8
Being a hill climbing specialist and having won a few hill climbs in my time I have to admit Edogawakikkoman's advice is wise and accurate. Don't over intellectualize your setup and start by understanding your comfort zone. usually for beginners, a compact with a 12-25 or 27 is ideal. the important thing that nobody has addressed yet is the massive stress climbing puts on your knees, ligaments and muscles. You definatey should be riding in one gear easier than you think you need when climbing because as you have stated, you are new to the hills. Chances are, your natural cadence is too low and you are a grinder. learn to ber a spinner before you power up climbs. also, look into perfecting technical aspect of your pedal stroke first, then worry about setup.

hope that helps
 

simon

Speeding Up
Jul 19, 2006
96
0
26
Tokyo
#9
Thanks guys!!
Really very much appreciated.
Lots of great information there.

Ok, no more questions from me on this topic...
My job title has "scientist" somewhere in it, so I tend to get hang up on details and calculations ;)

Hope to see you on a ride sometime soon...:bike:
 
Dec 4, 2008
170
3
38
Tokyo
#10
still on topic but a little more basic now; my crankset has developed a wobble, around 5mm left to right play around the axis of the axle, I'm no-one's idea of a bike mechanic, in romaji how would I describe the fault at LBS?
 
#12
Bure...

Right, "chainwheel ni bure ga dekite iru" should tell your mechanic what is wrong. If a good mechanic, probably no need to express the fault in words - even if 5 mm, which admittedly is annoying.

I had the same problem with my crankset (probably because I haven't learnt yet how to spin properly :( and grind too much on hillclimbs) and my mechanic found out right away nothing was wrong with the bottom bracket or crankarms...the delicate chainwheels (FSA) had simply bent from all the grinding. I had them replaced with Shimano cheapo & sturdy 105 chainwheels and so far no more wobble (even though I'm still in the bad habit of grinding my way up hills).


Probably closest would be "bure" or "ugami".

I'd try something like:

"Koko in 5mm gurai no bure ga arimasu".
 
Jan 14, 2007
2,516
213
83
Noda
japanichiban.com
#13
I somehow managed to get a 2 or 3mm bend in my front big chainwheel. May have been from changing gears on a steep hill or something... I think the only way to fix it though will be with a hammer or covering it with a thick cloth and applying a clamped vice slowly bending it back... :warau: (I only bought it a year ago too.). Doesn't seem to effect performance but when I look down and watch the little wobble it is annoying.

I'd like to create a little thread in the future (maybe a sticky if Thomas will stick it). Little Japanese phrases to use when going to the bike shop. Or a Japanese cycling terminology sub-forum... ?
 
Dec 4, 2008
170
3
38
Tokyo
#15
well, I still haven't fixed that fault, now this:

was just riding along, minding my own business, came to a sudden stop, as though someone had slammed the brakes on. Looked down, nothing amiss that I could see, flipped it over, the front wheel is locked solid, the pads are nowhere near the rim. The skewer is a non qr type, I don't carry any tools but did manage to free off the wheel, though it sometimes seems to impose a little more resistance than should be normal. There's been a noise coming from the front end for a while now, I had it as the headset/forks/or hub, guess the hub's screwed? Just what you guys would call a supermarket bike, Joytech hubs. Is it a new front wheel? How much/little should I be paying? I am not into 18 spoke front ends, I commute and use the road plus bunnyhop kerbs now and then. It's a rigid 700c type hybrid.
I know it's getting lighter in the evenings now but I have seen these tyres with a reflective sidewall, seem like a decent idea, is there any performance/durability penalty?

TIA
 

AlanW

Maximum Pace
Jan 30, 2007
1,214
436
103
Tokyo
#16
Sounds like the hub bearings have collapsed. It won't be worth repairing.
Look for a Shimano Deore or better front hub and have your bike shop build a new rim onto it. Mavic & DT rims are good, Alex rims are reasonable and cheaper and there may be some Japanese manufacturers too.

AW.
 
Dec 4, 2008
170
3
38
Tokyo
#18
Sounds like the hub bearings have collapsed. It won't be worth repairing.
Look for a Shimano Deore or better front hub and have your bike shop build a new rim onto it. Mavic & DT rims are good, Alex rims are reasonable and cheaper and there may be some Japanese manufacturers too.

AW.
Thanks - as I feared. Had Mavics on my old mtb, back in the day.

proxy.php?image=http%3A%2F%2Fi718.photobucket.com%2Falbums%2Fww184%2Ffhdfhgdjsk%2Fwheel1.jpg&hash=f66db72a71f1d54ffa3ecca7c219d6af


Is this one going to work for me? Is this a rim plus dynahub, built? Can I 'switch off' the resistance in the dynahub? They always seems like a good idea to me. I know it's devoid of sporting pretensions. Cast those aside long while back.

Wiggle has this: http://www.wiggle.co.uk/p/cycle/7/MWheel_Shimano_Deore~Mavic_A319_Front_Wheel/5360035958/

Was surprised to see that even a pauper like me can now afford Campag wheelset, GBP110, not that I think those would last more than a week . Seems as though Yoshida Cycles is priced fairly competitively, am I right?
 

Phil

Maximum Pace
#19
If I were going to go the dynohub route, I'd get the hub and have your LBS build up a wheel around it. You could get the LBS to order a hub for you. Yoshida has a few:

http://www.cycle-yoshida.com/parts/hub_menu.htm
(Second section, beginning with the HB-NX60-J(一般車用ナット止め))

The wheel in your screenshot is a 27-incher, probably for mamachari's(?)

Yoshida pricing is okay (for Japan), but after shipping/payment costs, it's often no cheaper than the LBS. They're useful because they put the entire content of the distributer's catalogs online, so you can pretty much always find what you want there.

Incidentally, LED lighting technology has really improved the last couple of years, and even randonneurs & commuters these days are choosing LEDS + rechargeables over dynohubs. Some links and info in this post.