Need lower gearing on older bike
 

I need some advice on how to cheaply get some lower gears on an older bike.

I have a 90' Trek 1400 with 105 1055 series parts that I brought with me from Chicago. 42-23 is not cutting it as a lowest gear. It has a 1055 crankset nonbiopace with 52/42 double and 13-23 7 speed cassette.

I was looking for an economical way to get some lower gears. I am wondering if I can get a 39 or lower chainring that is compatible. I am also considering a 12-28 cassette. I have a spare 8/9/10 speed wheel that fits in the dropouts but don't want to spend the money on new shifters and chain and cassette.

You could change the 42 tooth chain ring to a 39, but you may have to change your front derailleur. Anything modern for double crank road bikes should work because 52/42 tooth double cranksets are rare these days.

As for a new cassette, this would work fine. I hope you also know you can easily put a 7 speed cassette on an 8/9/10 speed wheel with a spacer that would probably cost about $1 from your LBS.

Measure the bolt circle diameter of the bolts which hold the chainrings to the crank. The BCD determines compatibility.

I think there is a limit to how much difference between your high and low rings your front derailleur can handle so if you go much lower than 39 you will need to change the big ring too.

The cassette would probabaly make a bigger difference than the rings. 7s cassettes are still available new.

Most likely you have a 130 BCD crank. The lowest ring you can mount on that is a 38.

I've had good success with getting a bigger cassette (maybe 12-32) and a mountain bike rear mech. A good 7-speed cassette would run around $20 and a usable rear mech would be about $20 (I found a Deore LX on sale for $17). This would make those hills considerably easier. You would also need a new chain- it would need to be a little longer.

There's an economical way... It's the "megarange/megagear cassette and new rear derailleur" approach. You get a 11-32 or 11-34 cassette (might be a bit hard to find though, 7-speed freewheels are more common in those configurations, you'll probably have to go with a non-Shimano cassette) and a new rear derailleur. You can get an Altus, and Alivio or a Deore all below $25.

Then again, a 12-28 should work just fine with your 1055 RD. Might even take up to 30 big cog, but that's pushing it. Of course, a 11-34 megagear will give you a lot lower first gear

http://www.txedbike.com/cd/TRA/img/FW258-7KMST.jpg

there is a chance you have a 110bcd crankset, in which case you can have wonderfully low gears. All you need is a new rear derailer, freewheel/cassette, front derailer and inner chainring.

That should run you about 100 or so, and get you up just about any hill

I guess a 12-28 is the way to go. I love to go 9 speed but I figure I'd need

1. new shifters probably Barcons +DT barrel adjusters + cables/housing&tape ~$100
2. New chain $15
3. new cassette $25

Over $140 not worth it really
My good road bike has 39-25 and seems sufficient.

+1 Wider range 7 speed cassette and a new RD. Cambria has a nice Deore RD for under $20. Tough to beat.

I would go with the 12-28 cassette and a 39 inner ring. Your BCD is probably 130, but check for sure.

Al

If you bump the weight up in adding a new cassette/longer chain/bigger derailer, you will of course like that lower gear even more. :D Seriously, though, I'd guess that your sweet spot would be more of a larger ring 7-speed than an 8- or 9-speed plus new derailer etc.

If you have a 7 speed freewheel, you can ick up a 13-34 for about $20.00 ( check Harris cyclery for comparisons). A 7 speed 12-34 cassette is more at about $30.00. A Deore RD and new chain would put you in business. Depending on your shopping skills it should com in at $50- $70. I like the Deore because it has a shorter cage than the LX, and is cheaper. I run a similar setup on my 8 speed and it works great.

No chance of that. The OP specified "1055 series" parts, which is Shimano 105. Shimano 105 was 130mm BCD for all of the '90's and most of the '00's.

A 13-34 cassette and "mountain" rear derailleur, along with a 38 or 39-tooth inner chainring will get you up a lot of hills unless you're loaded touring.