mawn

Hi, I'm used to easy gear in my mountain bike (Trek 3700), Crank 42/34, and 7-speed Cassette 12-32.
I like to do some challenging climbs (18%) in my city, but with my new bike, I find it very hard with a 52/42 Crank and 9-speed Cassette 13-23.
Climbing, I prefer a high cadence to grind.
For flat, the bike is excellent. I like it!
What should I upgrade first, the Crank or the Cassette? is it possible?
Thank you

Bald Paul

Definitely change the cassette, but make sure your rear derailleur can handle it.

mawn

how can I ensure that my rear derailleur can take an 11-32 cassette?

cxwrench

You derailleur can't take a 32. 27 was the max cog for that derailleur, you can use a 28. Also change the 42 chainring for a 39 OR just buy a compact (50-34) crank.

mawn

in that case, Who will have more impact, the compact (50-34) Crank or the 28 Cassette?

Koyote

​​​​​​https://www.bikecalc.com/gear_ratios

You may not have bought the best bike for climbing an 18% grade.

Iride01 

Are you certain the small ring is 42 teeth. I'd rather not sit and count them so I'm leaving that to you. 36 would be more common paired with a 52 ring. But older stuff was sometimes different.

If it is a 42 ring, then a 36 ring will give you some easier pedaling to keep your cadence up. And you still will need to find out what the spec's are on that DR. The model number should be stamped on the backside of the parallelogram. Then you or someone can look it up. Max front difference is one of the specs you'll need to check.

Rings can probably be found inexpensively for that old crank. Though you need to know the PCD or BCD of that crank spider to determine if a 36 will fit. Also just check for entire cranks. Assuming that is a BSA threaded BB shell, then you should have a lot of crankset choices. For me, the 2 piece Hollowtech II cranks are easy to install and work great for road bikes.

mawn

yes, it's 42.. behind the Crank, there is "Shimano SG A-52-42-30".
I don't understand very much about PCD or BCD. so I think I need to check with a Bike Mechanic.
Thank you

aliasfox

Before changing out cassette or cranks, you may want to double check how much wear is on the chain. A chain checker would do this, but a ruler should be able to tell you as well. If you put one pin at 0", there should be another pin right at 6" (or 15cm). If that pin instead falls past 6 1/8" (possible with an old drivetrain), switching out just the cassette or the rings might cause the chain to skip, especially under high-torque conditions. In other words, if you're going to change one piece of your gearing, don't be surprised if you end up having to change out the other two pieces, as well.

The generation of 105 you have also had the option of a triple crank and front shifter, which would give you a 52-42-30 front end. My Bianchi has an Ultegra 52-42-30 triple in front and a 12-27 cassette out back. It's actually not as low as the 1:1 ratio that some bikes come with today, but it's close, and I get to keep the tight ratio cassette. Just looking on eBay, switching out to a 105 triple front shifter and triple crank would run about $200 in parts + shipping + installation.

Bald Paul

52-42 cranksets were very common at one time.

mawn

Thank you for the tip!!
A 52-42-30 will not work for me. The 30 is too low. I prefer a 36/38 or go back to 34.

aliasfox

A 30T ring might be too low if your cassette goes up to a 30, but your cassette right now looks to be a 25T. 30/25 = a gear ratio of 1.2; that's pretty close to a 34/28 (1.21). It's also a lot steeper than 34x34 (1:1) that a lot of newer bikes come with these days. Remember, it's not just the front that matters, but also the rear, and how the two play with each other.

As someone else said, you could go to a 27 or 28 big cog in the back, but that'll only buy you about ~10%. To be honest, for the first 15 years, I never touched the granny ring on my Bianchi - never needed it. I never climbed anything greater than 10% for very long, and nothing that was long was greater than 7%. And then I met the Coleman Valley Wall: 1.1 miles at 13% average. Oh boy did I appreciate that 30T ring!

mawn

I got you. Thank you so much!!

terrymorse 

Coleman Valley Rd, up from Highway 1?

That is a little leg stinger. This is yours truly, riding up it for a Sonoma County promotional photo shoot.

The road was used in one of the Tour of California stages. You can see "BMC" painted on the road.

aliasfox

That's the one! It's not the longest climb, but it has a grade that just won't quit! That said, rising up 800ft, almost straight up from the shoreline, is a magnificent site. I rode it twice as part of Levi's Gran Fondo, and it was one of the segments that made that ride truly special.

caloso

I know that climb. It's a doozy.

genejockey 

Swap the 42 for a 39 and get a 12-28 cassette. The RD looks to be a long cage - which makes sense it the crank was originally a triple - so it should handle that with no problem.

I'll stick with the climbs on the Peninsula, thanks. 1.1 miles of 13% average sounds like hell.

Iride01 

Well 52-42-30 implies that it is a 3x capable crank and for some reason doesn't have the inner ring. So if your STI for the front is 3x, then you only have to find an appropriate inner ring and add back to it. Then you'll have plenty of low gear ratios to choose from as well as higher ratio gears.

And if the STI is 3x, then I'll just assume a previous owner took off the inner ring and that if the rear DR is also original to the bike that it will handle a front difference on the front from 52 to 30. But you should find that part number on it and be certain what it is if you are wanting to change gearing.

Of course after adding the small ring back you'll need to adjust the front DR and maybe the rear too to get perfection.

PCD is pitch circle diameter and BCD is bolt circle diameter. They tell you the same thing with the same number, but they are determined differently. Essentially it is the diameter of the circle on the chain ring that the chain ring holes are drilled on. So you have to know what those are to be certain you get the correct rings for it. The inner rings on 3x cranks usually were a different PCD or BCD and may have required inner ring with holes for it to attach to or some other method.

Carbonfiberboy 

I have been riding a bike of that vintage for 22 years. Back then, the better the bike, the smaller the stock cassette. I don't know why, but I've always assumed it was either for the buyer's ego or the manufacturer thought that the more money one had the stronger one would be. Seems reasonable, doesn't it?

Anyway, what you want with a 9-speed rig is a smaller chainring rather than a bigger cassette, that is until you get too old for that cassette, at which point you go to a larger one. The reason is simply that smaller cassettes have closer ratios. But that would require your having a triple left brifter, front derailleur, and crankset and I doubt you have any of those. So you'll have to put on a larger cassette unless you want to change all that out, if you can even find the parts. Look on the inside of your crankset. Is there a threaded post on every arm? If so, you already have a triple crankset, just without the 30T cassette.

Your MTB low gear was 34 X 32 which is a 1.06 ratio. To get that ratio with your 42T would mean a 40T cassette. BCD means Bold Circle Diameter. Yours is 130mm. 36T is the smallest 130BCD chainring. If you change down to a 36, a 34T cassette would be perfect. That's an MTB cassette of that period, so you'd need an MTB rear derailleur. The best is a Shimano RD-M952 XTR. Search for it on ebay. There are several listed right now. Get one.

Of course you'd also need a longer chain. I suggest starting with a chain that's long enough to go big-big plus 1 link. If that doesn't work, i.e. gets too loose in gears that you'd actually use, you'll have to shorten it and just remember not to overshift and ruin your rear derailleur. In my experience it's better to have the longer chain and just learn which ring to use with which cog.

Carbonfiberboy 

Re post #18: if you had a triple left brifter, you'd already know it because you'd have shifted down off the small ring and had the chain down on the frame. But just to check, see if it'll shift one more click down from the 42.

genejockey 

It's also possible that a previous owner removed the 30, then adjusted the lower limit screw to prevent the FD from dropping past the 42, then set the cable tension so that the lowest click corresponds to the 42, and then a properly set upper limit screw would prevent upshifting past the 52. That would prevent the FD tossing the chain onto the BB shell, and/or the cable going really slack when the STI releases the cable tension all the way.

Iride01 

Maybe, but I was thinking that the low limit might have enough adjustment to preclude that from happening.

Carbonfiberboy 

The presence of the posts on the inside of the crankset should tell the tale then. I think this is a likely explanation, since the set does say 52-42-30. in which case the chain is OK, all the bike needs is a 30, quite inexpensive since it's just a plain ring, no ramps, 74 BCD. Bike shop can handle the adjustments.

big john

If that bike originally had a triple and the shifter is still there, just put a 30 on and adjust everything and ride. You could put a 39 middle ring which might be more useful.
The 30 can't be "too low" for a steep grade. A 30x23, which would be your lowest gear, isn't as low as the 34x32 modern bikes have. Plus, you could shift to a smaller cog if you're spinning too much.

If the 30 works you can ride virtually everything while you decide if you want to change things and it's the cheapest way.

I have a triple bike I ride sometimes. It was built with 52-39-30 and a 11-25 cassette. A wide gear range and I've done a ton of climbing on it, at least a couple million feet.

cyclezen

9 speed 105 from the Octalink era...
cassette looks like 12 to 23, to my eye...
cranks, given what you say is on the crank, COULD be a triple crank... look at the backside of the crank, if there are 5 empty bolt posts (female), one each on each crank arm near the axle/spindle center - then it can take a granny gear - usually a 30. Best, cheapest way to get the gearing needed for climbing ... IF the Brifters are also triple... Lift the rubber hood on the left/front shifter - under that will be a Model #... triple model numbers/names usually end on an '03'...

Shimano 9 speed Octalink Crank - BB/inboard side

Triples are great for a broad range of gears, and the shimano triples from that era work great - when properly set up. 'Bikie' fashion has poo-poo'd triples, but they have always worked well for me.
And if the motor is good, who cares? Ignore fashion, function over fashion.
Dial your guads up to 450 and droop the naysayers... LOL!
Ride On
Yuri