P. B. Walker

Hey all,

I've recently converted my MB into my commute bike. It's a early 1990's GT Outpost. It's got all Shimano in the drivetrain. I've recently replaced the cogset with a 12-28, plus put on a SRAM chain. About two years ago I had to replace the front derailleur. I think they put a Deore XT on it. The Crankset is all originial though. I believe it is Shimino Acera (sp?). I counted the teeth last night and it's a 24/34/42 combo. It's not enough. I need higher gearing. I'm spinning out on the flats when I'm in the 42/12 gear. And I'm almost NEVER use the small chainring (24). I have one monster hill on the way to work (10-11% grade, 0.4 mi long). But I usually go up that in the 34/28 gear.

I've looked at the big bike shops on the web (Nashbar, Performance) but all the ATB Cranksets I see are 24/34/44 or 22/32/42 combos. I think the XT is 24/34/46.... but it's like $450. That's too much for me.

Also, after looking at what is on there, it appear to be all one piece. I don't think I can just replace the largest chainring or the middle chainring.

So, I was hoping someone could point me to a place that has different gearing options. And is still compatible with what I have. I don't mind buying a new Bottom Bracket and Front Derailluer as long as I'm not spending $500 or whatever. I guess, I'm willing to go up to $100 or $150. I just want this bike to last me thru til next summer. I'm planning on buying a new MB and building it from scratch.

I've also checked Sheldon Brown's website but have only found his section on cogsets. I can't seem to find anything about cranksets.

I'm kinda looking for one of the following combos (or a mixture thereof):

26/36/46
24/36/48
28/38/48


I don't want to go higher than 28 on the small chainring and I don't want to go higher than 48 or 49 on the large chainring. I think a 34 or 36 would be perfect for the middle.

Thanks for any help you can provide.

PBW

pokey

Sugino makes a triple with 28/38/48 for that takes a 110 or 113 spindle.Check www.branfordbike.com

Maelstrom 

https://www.raceface.com/components/

These guys make a durable (one of the most) chainrings and has all the sizes you are looking for.

You could find more difficult terrain where the high gears are useless. I haven't used a big ring in a year

https://www.bikecanada.com/catalog/co...acerings.shtml

Those are some prices...in canadian

P. B. Walker

I've heard of RaceFace before. They look good. Since what I currently has doesn't look like it will allow me to just replace one or two chainrings, do I need to buy 3 new rings, PLUS the cranks? What about a bottom bracket?

Would my Deore XT Front Derailleur work with this setup?

Since I can't really do this work myself (no tools and never done it before) I'll be taking it to my LBS. Should I bring it into them and have them look it over first? Maybe they have a supplier for RaceFace also.


PBW

P. B. Walker

Good idea, except about the only thing I use this bike for is commuting, and riding the C&O Canal Tow path, which is completely flat. That's about the only offroading I like, maybe single track, but only if it's not super hilly.

PBW

Maelstrom 

I was sort of joking...I would need a 3 ring if I commuted long distances. I would get frustrated by the lack of speed two rings offer on regular surfaces

Maelstrom 

the only answer I know for sure is that yes th deraileur should work with a little tweaking I assume.

I totally forgot that you may need to change the bb to splined and get new cranks. Sorry about that...sometimes I start typing before my brain turns on. I assume you have a square bb which means an upgrade plus the cranks...that adds up...(you only need three tools...one to remove the crank off of the bb, one to remove the bb, one to put the new bb on in. Since I have never worked on a square taper bb and the splined may not even work I am really just babbling..I will leave this answer to someone more knowledgable (like your lbs...)

P. B. Walker

Maelstrom

Thanks for the help. I at least know there are options now. I think I might drag it into the LBS one of these days and just see what they can offer me. Like I said, I'm trying to keep it in the 100 to 150 range. But these gears on it now are driving me nuts. I can almost forget about pedaling down hills at the moment.

PBW

Michel Gagnon

Do you spin your pedals at 70-90 rpm? If you are one of those that pedal very slowly, try to increase your cadence. This will be a much more effective way to gain speed.

Now, back to the subject...

Check Sheldon's cassette page and check whether or not your freehub is compatible with a cassette that starts with an 11. If so, that would be your cheapest option. Using 42/11 gives you 103 gear-inches... or the equivalent of 46/12. Since you rarely use your small chainring, you might try to get a cassette with closer ratios like 11-23 or 11-25.

P. B. Walker

Well, when I get into 42/11 gear and spin out, I'm doing about 100 rpm. I can't do much more than that. Actually 95 is about my limit. And that's on flat or slightly down hill.

According to my calculations, going from a 12-28 to a 11-28 or 11-24 is only going to get me a few gear inches on the top. For a 26 inch wheel, I calculate 42/12 to be 91 gear inches and a 42/11 to be 99.32 gear inches. That's basically one higher gear. That might do me for the flats, but the slight downhills and even full downhills I'll still just be coasting. I'd rather have the option to pedal downhill for more speed.

But, this does leave a good last option... it'll get me by for the flats.

PBW

John E

A few options:
1) Get an older-model crankset with a 110mm BCD, for which 46 and 48T outer rings are commonplace.
2) All high-quality cranksets have individually replaceable chainrings. 44/11 x 26 = 104 gear-inches, which is a respectable high gear for most applications.

pokey

Even the crankarms for the shimano road triples will take 48/38/28 rings.

Feldman

Get a bike computer with cadence and learn to love the number 90.