swapping gears question
 

I have a '90 trek 1400 with shimano 105 components, 7 speed, DT shifters.

I'd like to get some new gears and try them out. Something with a little better hill gear and I'm looking on ebay and it looks like I should be in good shape but I'm not sure.

I have 13-23 shimano hyperglide gearset according to the old manual specs I researched.

Would something like this work? It is 11-28 (11-13-15-18-21-24-28)
http://cgi.ebay.com/BRAND-NEW-SHIMAN...QQcmdZViewItem

Would this be plug and play? Do-able for an amature wrencher?

Would I have to get a new chain? I can't imagine why this wouldn't work and it looks as if it'll really help on the hills. I can always go back to the closer gearset currently on the bike once I get better.

Also, is there a way to mix and match with my current gears? Just swap out the 1st and 7th gear?

Th front rings are 53-42

I was just wondering about compatibility. Chain length etc.
Doesn't seem like an issue but I want to be sure.

All things being equal (compatable freehub, no Dura-Ace) it should swap right out.
You MIGHT need to lenghten the chain a bit.
Top

It will work. A new chain is recommended but not needed if your current one isn't too worn.

One possible issue is that not all HyperGlide freehubs will take a cassette starting with an 11T cog without some fudging. If your freehub is "non-compact" (in 1990 I think most were non-compact), you may need to either grind some material off the end of the freehub splines or put a 1mm spacer behind the cassette or replace the freehub body with a "compact" one, or build a 13-28 by combining the two cassettes (assuming the original cassette isn't too worn). See http://sheldonbrown.com/k7.html#hyperdrivec

You can mix-and-match cogs somewhat, especially with the larger cogs. Usually the top position cog must go on top and the 2nd cog must go 2nd. But that depends on the cassette cogs and is not a hard and fast rule. The HyperGlide ramps won't match up when you mix cogs so shifting performance will suffer slightly - but I've mixed HG cassettes and haven't noticed loss in shifting performance.

You could replace the 42 inner chainring with a 39 to get some help with the hills.
I like Gonzo Bob's idea about combining the two cog sets into a 13-28.
The 11 cog's more trouble than it's worth.
Measure the chain for stretch. A 24 pin interval should measure exactly 12 inches. You should replace a chain by the time that length becomes 12 1/16th inches. Use a good steel ruler.

Al

Thanks. I'll look into mixing the cogs as well.
I don't use the 13 much and maxing out the gearing with 53F to 13R gets me plenty of speed down hills. I'm not racing. Probably changing the 7th and 6th is all I need to do.

I'll also look into the 32 inner front ring.

I have a '92 Trek 1420 (the triple crank version of the 1400) that also came with a mix of 105 7-speed components and indexed dt shifters. The hub is hyperglide compatible and takes any Shimano current 7-speed cassette. Loose Screws (www.loosescrews.com) has Shimano 7-speed cassettes available in 13x28, 13x30 and even 13x34.

You will probably need a new chain since the change from a 23 to a 28 will require 3 "half links" more length and the 30T or 34T cogs will certainly require a longer chain than you have. Also, your old chain will most likely skip on a new cassettes so go ahead and get a new one.

Your 105 double rear derailleur will handle the 28 and most likely the 30T large cog. The 32 is probably beyond its ability.

Finally, a 38T chainring is the smallest that will fit on your 105 double crank (130 mm bolt circle diameter) and 39T rings are far more commonly available.

Great info, thanks!
I read up on the sheldon brown site and it looks pretty do-able. Thanks for the insight. Good to know I can upgrade this aging bike.