I am the original owner of a 1995 Diamondback Sorrento MTB Hard Tail. While my primary riding is a Garry Fisher HooKooEKoo on dirt trails, I occasionally (ok, rarely) still use the Diamondback as a road bike (think Rails-to-Trails type conditions).

I've been riding long enough that I never need granny gear (especially on road-like surfaces), yet the MTB gearing of the Sorrento seems to be holding be back on the top end (I'm a slow power peddler, not a high cadence peddler). I would like to do something like put a larger set of chainrings on the Sorrento, but I don't want to spend a lot of money. After all, brand new, the bike cost my only $300, and again, I rarely use it.

On my own, the best I've been able to possibly come up with is this crankset (assuming it will work with my existing front derailleur), but I don't know if it's worth my time to swap out a 24-34-42 for a 28-38-48.

FWIW, all parts are either original to the bike, or replaced with like components. The only components I recall ever replacing have been tires, brake pads, cables, chain, cogset, and a derailleur.


Will the 28-38-48 even swap out without having to buy additional equipment? Other crank sets to suggest?

Key to know Bolt circle diameter.. for the 34t in the middle, thats smallest on a 110 BCD.

smaller than that seek a smaller bcd.. as such a 22,32, 44t set is practical ..

compact mountain , many are 4 bolt now.. 110/74 are usually 5 bolt.

Look on the inside of the DS arm and look for a model#. It should be something like FC-Mxxx.
It appears the crank you linked to requires a 122.5MM BB. Your existing crank may or may not use the same spindle length.

You could probably get it to shift with your current FDER, but expect it to be less than stellar.
It'd be better to spend the $15 or so for a FDER designed for the larger rings.

"(I'm a slow power peddler, not a high cadence peddler)"

I'd suggest learning to spin faster; it is better for your knees and drivetrain and doesn't cost anything for parts.

I'm not very athletic (hence the reason for my riding style). But I've been riding since I was a teenager. With only a few years to go before I get to joint the https://www.bikeforums.net/forumdispl...fty-Plus-(50-) sub-forum, my cadence style isn't going to be changing any time soon.

Sounds like you're talking about only changing out the chainrings. But I'm under the impresion that the Shimano AceraX crank set was bolted (or welded) together such that you can't replace individual chain rings like I can on the Gary Fisher. So based on my limited bicycle mechanical work to date, I think I have to change out the whole crank set.

I've never changed out a crank set. Are any special tools (beyond metric alan wrenches) required?

Of course the other thing I have not considered is that going to a larger chainring is going to possibly require a longer (i.e. replacing) the chain as well. This is starting to sound like I might be spending way more that I was expecting/hoping.

Irrespective of your preferred cadence, installing higher gears will not increase your speed, unless you physically cannot pedal fast enough in your current setup. Gearing only affects the amount of pressure you put on the pedals, not the power you transmit to the wheels. It is an incorrect assumption that riding in a higher gear one will be able to pedal at the same rate and therefore go faster. If that were true why would you ever be in a lower gear?

On rails to trails conditions, such as a crushed limestone path, that is unlikely to happen unless you pedal extremely slowly. In the 42/11 gear at only 60 rpm you are going almost 18 mph, which is quite fast for those conditions. 70 rpm is still not very fast pedaling and would get you 21 mph.

In any case it appears that the crankset you are considering will also require a different BB, as the OE crankset took a longer spindle.

NOTE THIS ENTRY FROM SHELDON'S SITE:
Acera-X M290 Triple 110-113 Square 47.5-50 Recalled! Do Not Use! See Shimano dealer for free replacement. Compact 1995

p.s. It's pedaler not peddler, unless you're talking about there rate at which you sell stuff.

yup .. free is good, and good for you.

42 is quite a small largest chaining - it is actually sometimes found as the smallest chainring on road bikes.

A 48 would be an acceptable high gear for most people, but so much so that when pedalling at a reasonable cadence, most people would not get into the big chainring/smallest 2 or 3 cogs very often.

THe good thing about training your legs to spin is that it is a win-win-win - you will go faster, you spend nothing, and it is better for your body. As you age and you start to have more joint pain, spinning higher rpm to go the same speed and distance will offer releif and less wear and tear.

This is excellent advice but not always possible to follow. I've been riding for almost 28 years and over 170,000 miles and have NEVER been able to train myself to use a fast cadence and, heaven knows, I've tried many, many times. About the best I can maintain is 70 rpm and attempts to make myself spin faster in lower gears just leaves me winded and going slower.

Maybe I've been lucky but I've never had any knee problems despite mashing bigger than recommended gears up all kinds of hills.

I'm an engineer, so I understand the logic of what you are trying to say.

Here's the thing. The combination of growing up in the foot hills of the Appalachine mountains, and having a relatively low athletic (i.e. cardiac) ability has created the situation where is it easier for me to apply power at low cadance. To me, a comfortable cadence is something on the order of 30 to 45 rpm. The result is that on a paved path, I'm getting a top speed of about 12mph at my comfortable cadence level yet feel like I still have power researve that I can push HARDer (just not faster).

Thanks for the info

Once again - I'm an Engineer I'm good with numbers, not words and certainly not spelling.

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• Pushing a 48/11 at 45 rpm or less s a recipe for physiological disaster - specifically your knees.
• Cardiac ablilty is not fixed and there are huge benefits to increasing it.
• What is easier physiologically is very much a function of to what you are accustomed. It does not take long to train your body to work at a higher pedaling rate, and having your heart beat faster to do so will result in it actually beating fewer times in the course of a day.
• Pedaling at a higher rate will at first be more difficult, to the extent that your heart will beat faster. But upping your cadence only to 51 rpm gives you the same increase in speed at a much lower cost to your knees (and feet) as well as wallet, and a much greater benefit to the rest of your body.

+1. I've gotten a lot faster just by speeding up my feet. It didn't feel natural at first, but now I (especially my left knee) prefer it, to the point that I've actually re-geared most of my bikes to lower my top gear.

That's the same calculation I've made.

I dropped by a LBS to get a quote or parts they thought would work with this type of modificatione. The total was about $75 (crank set, crank set tool, chain, and MY labor). Given how little I ride this bike, the modification just isn't worth it at this time.

If I start doing less trail riding on my Gary Fisher and start doing more road riding, I might revisit the issue (or save the money to just buy a "real" road bike when finances allows).

Thanks for everyone's input.