Options to Change Lower Gearing
 

I have an old 8 speed Shimano 105 set up on my 1994 Tru Temper framed road bike. I just got it out of the shop yesterday and during my test ride, I'm fairly certain I'm gonna need a lower low gear (Currently 39T). I know I can ask the shop guy what to do, but I want to hear from you guys what you think. Can I go to a 9 speed or do I just need to change the small sprocket on the front to a smaller one? What am I allowed to do without changing my shifters? I never used the larger front sprocket (53T) at all yesterday. The cassette is a 12-23T.

If you have a 130bcd double, with a 39T chainring. Look at how close the bolts holding the chainring are to the teeth on the lug. For 130bcd, the smallest chainring you can use is 38T.

You can swap the crank to a 110bcd "Compact" crank. which would allow a 34T chainring, and perhaps a 50T big ring if that is appropriate.

Jumping from 8 to 9 speed is usually easy if you have "friction shifters". You would probably need to also replace the chain. If you have indexed shifters, you may need a shifter upgrade.

The quickest and easiest would be to switch to an 8 speed cassette that goes down to 28 teeth. You would also need a slightly longer chain to accommodate the extra teeth. If your shifters have an extra notch or are friction, you could use a 9 speed cassette, but most likely you are stuck with 8 unless you change the shifters.

Another option would be to change the crank to "compact gearing", or 50-34 combination along with the cassette change. That would involve a lot more work and may require changing the derailleurs to allow for the extra chain, but you would get a wide range of useful gearing.

+10 Attack the cassette instead. Will also need a longer chain.

Going to 9 speed = serious money, mainly for new shifters, plus 9 speed chain and cassette. It adds up $$ wise.

Go to the Sheldon Brown site and play around with the gear calculator. You can quickly see the effect of changing cassettes, going to compact crankset, etc.

When you hear hoof beats think horses - not zebras! ;)

In other words, choose the simplest, cheapest, easiest solution rather than reinvent the wheel.

53-39T chainrings with a 12-23T cassette is pretty much a racing setup.

A 9 speed cassette wont do much for you unless you go to a larger rear sprocket. It will probably mess up your index shifting too!

The simplest solution is to find an 8 speed cassette with a 28T large sprocket. You'll have to look around but 12-28T and 13-28T cassettes are still available - check out eBay. You may have to pay $50-60 for a good one. Look for a Shimano or maybe an SRAM. Most modern rear derailleurs will handle that regardless of what the listed capacity is.

You will probably need a longer chain too.

I run 48T or 49T large chainrings with 38T or 39T small chainrings and 8 speed 11,12 or 13 to 28T cassettes on a number of my bikes. Several have 30T large sprockets and my Shimano 105 rear derailleurs handle them fine.

This is one of those bikes - 48-38T x 11-28T 8 speed:

http://bikeforums.net/attachment.php...hmentid=452512

While you're changing the large ring you could put on a 38T small chainring but it wont buy you much.

I'd start off with a new cassette and chain before spending a fortune on a lot a fancy "improvements" that may do little for you.


verktyg :50:

Any thing over 8 speeds enters the Spinal Tap realm of 11 on the volume control! :lol:

Chas.

I would first ask where do you ride and what your overall weight and fitness level is. If you ride where the hills are steep and your power to weight ratio is less than ideal, you should consider a new crank and a new cassette.

Are you on a budget? Than just change to a wide range cassette, a new chain and a Deore rear derailleur.

Changing from a 12-23 to an 11-28 is a small improvement, but is probably not enough if you have 10% hills to climb and you're less than fully fit.

I'm not fully fit.... Not on a budget....

I rode a 6 mile bike trail yesterday and spent a lot of time in the lowest 2 gears on my cassette. The 53 T large sprocket is a total waste. My body wanted another lower gear or two. A couple of local bikers have made mention of the larger crank set and raised their eyebrows, tilted their heads and smiled and asked me to let them know how the hills work out. I live in SW VA on the eastern edge of the Blue Ridge Mountains.

I can get a 12-34 or a 11-32 Cassette from Rivendell. Would that "Solve my problem?" Or a 11-28T

Probably not from your description.

I will be contrarian and suggest a triple front.
I read into it that the bike had not been used, got serviced and the gearing/terrain/rider are not well matched right now.
You will also need a long arm rear dérailleur most likely too to match a triple or a 32 or 34.
You might look up veloorange. They have a few triples that you should run the gear charts with.

My other recommendation is N+1. One reason I like rigid mtb drop bar conversions is you get super easy gearing. Not only will they have a triple up front, but all the rings are usually smaller to boot. They have the long cage RD, etc. Save the racing bike for club rides, flatter terrain, etc. I live in the mountains, I can't go one block without climbing a hill. I am basically at the bottom of the hill, so coming home I enjoy the down hill ride!

IIRC the 8 speed 105 STIs are double/triple on the left side so you could probably run a triple without too much trouble. I like the sugino xd600 with 46/36/26 rings and an 11-28 or 11-32 gives me a crazy amount of gears with enough low gears to crawl up any of the hills I run into around here. I'm still a clyde so I find I need the lows more than most people seem to.

I will too. I like triples.

If you've got an 8 speed rear end- I'd keep the 8 speed, get a 12-28 or 30 cassette. Throw a 110/74 triple crankset on the front end. That gives you a whole lot of options for cranksets, and chainrings. I think it's possible to get down to a 24 (but that's really TOO low for anything but pulling a loaded bike up a hill and you don't want to walk for some reason). Otherwise a 46-36-28 front end is a popular MTB combo.

I went from a 12-21 to a 11-28, and I can now get up pretty much any climb I've tried.

While I like the easier climbing gear, it took me a bit of time to get used to the wider ratios. Sometimes I'm looking for that in-between gear, like when you are starting to pedal hard, you down-shift and now your spinning to fast. I miss the closer ratio that the 12-21 cassette had. So IMO, the wide ratio does have drawbacks. And to be honest, except on the steepest climbs, I rarely use the 28 gear, as I find I'm spinning to fast and it leaves me breathless. I'd rather have a little more resistance and pedal harder.

So I think that change would be all you need, just remember your getting a very wide ratio.

I also agree with the triple. The fact that your not using the larger chainring is another indicator your gearing is all wrong.

Go with something like;


Use this crankset: http://www.outsideoutfitters.com/p-2...77saAsBa8P8HAQ
This rear derailleur: http://www.ebay.com/itm/Shimano-Deor...item3cfa17c946
This front derailleur: http://www.ebay.com/itm/Shimano-Deor...item3cf9745f6c

Almost any 8 speed cassette will work. the 11-28 is a good choice with this crank. A 13-26 has tighter cog spacing. Either will get you up any hill.

http://i289.photobucket.com/albums/l...pse1d95ae4.jpg

Your mistake was choosing 11-28 instead of, say, 13-26. Don't waste your gear combinations on high ratios you do not need and seldom use.

I can get a nice tight ratiometric progression and reasonable range with 12 gears: 50-42/14-16-18-20-23-26 or 45-42/13-15-17-20-23-26. With a 38T inner chainring and 8 cogs, one could go higher on the top and/or lower on the bottom without spreading the gaps too widely. For example, consider 46-38/13-15-17-19-22-25-28-32.

No arguments there, your right.

But I've found that this cassette is better and more useable when I'm in the big chain ring, where the ratios seem closer and I can actually use the 28 gear for small hills and starts, and it's plenty comfortable for most of my riding...

Isn't the solution obvious?

Buy another bike.

Gebo, From what I've read, I don't think you're going to be satisfied unless you change gearing at both ends. I suggest a 50-34T compact double with a 13-26 8S cassette. You may need a new, longer chain. A new compact double will probably be designed for outboard bearings, which are often included.

If your front shifter is STI and able to also shift a triple (your bike shop can verify) I suggest a 28-38-48T triple crank set with the 13-26T cassette. This will also most likely require a different bottom bracket (may or may not be included with the crank set), a different rear derailleur and probably a triple front derailleur that is compatible with the 105. This is more expensive...

Brad

PS I forgot to add this chart from Sheldon Brown:
34 14.7 % 39
23 38.8 44.6
13.0 %
26 34.4 39.4

Well....that is not an option at this time. I like the idea though!

Looks like you might also be able to go with an 11-34 cassette if your rear derailleur can handle the required chain wrap.

Cassettes from Harris Cyclery

But if you have a standard short cage rear derailleur then your options are more limited.

Ignore the cog counts in the following threads and look at the chain wrap tooth count options to figure out what you currently have can handle.

http://www.bikeforums.net/road-cycli...-11-speed.html

http://www.bikeforums.net/road-cycli...railleurs.html

edit to add link to your previous thread so people can help you better:
http://www.bikeforums.net/classic-vi...e-r-104-a.html

Triple conversions are very expensive - new crank, bottom bracket, front derailleur, brifters, chain, maybe rear derailleur too to handle the wrap. I wouldn't do this unless you really love that particular bike. A new bike with a triple would probably be a good choice for your NEXT bike though.

The wider cassette option is the most obvious - maybe 28t is enough - don't have to change anything else.
The alpine cassette option with new wide range rear derailleur and 32-34 teeth would almost certainly give you low enough gears with your standard chainrings.
And the next step would be a compact crank if you still need more... won't need new derailleur or brifters.

I've had bikes that were already drilled and threaded for a third chainring and would only require adding the smaller chainring and associated spacers and screws, then adjusting the front derailleur to be good to go. If you don't have the necessary chain wrap on the rear then you have to be aware of what gear combinations will work and which won't.

But I don't have the OP's bike in front of me so I can't say for certain what his options are.

Time to fire your bike shop. Changing the crankset and suggesting "9-speeds" is the most invasive and expensive possible solution. Translation to their recommendation: "we're going to make this so difficult that you'll just buy a new bike".

Change out your cassette. You'll also need a longer chain. This is less than $50 in parts to go to a (say) 13-30 8-speed cassette. Or a 12-30. At any one time there will be 100s of these on sale on Ebay. I am doing this exact operation on a ladies bike this evening. It will take less than 30 minutes. And I'll take apart and repack her hubs with fresh grease just for the hell of it.

If you want to go even lower, say to a 34 tooth cog, you'll need a new mountain bike derailleur. Say a 9-speed Deore unit. I'm assuming you're using Shimano indexed shifters here. This will work on an 8-speed drivetrain. Now you have pretty low gearing. Try this first. If you need even lower gearing, such as for doing 3,000 foot climbs in the Alps, or loaded touring, then you'll want to change out the crankset as well. This gets expensive.

It wasn't until the model 5500 9-speed shifters arrived that the double/triple compatible shifter appeared, so the OP's left shifter is a dedicated 2-ringer. There were accessory flip-lever things from Ericson I believe that allowed use of a triple.

Since the OP isn't a racer, I'll suggest a 12-32t cassette and matching off-road rear derailer. One doesn't need tighter gearing than that unless they are racing regularly imo. The bigger cassette will offer about three more downshifts compared to the 12-23t!

Note that the chain length needs one link added for each two teeth added to the largest front or rear sprocket, and an extra couple of links on top of that will easily be taken up by an off-road MTB derailer.

I would also ask the OP if a road-racing bike is their first choice overall, in which case the size/fit/geometry of the bike is another huge consideration. Since the road bike is what the OP already has, the gearing spread seems to be the easiest change though.

It's not the first choice but it is what I have. I just need lower gearing and it appears most of ya'll say to go with a different cassette. That's what I'm going to try first.

M900 or M950 XTR cassette turn up all the time on Ebay for $30-60, and are an especially fine cassette that is offered as a 12-32t, 8-speed. I even keep these in stock these days.