Hi- I am trying to compare bikes and have two general questions. First, what effects do various subtle changes in geometry mean? For instance, in comparing two bikes, a 56cm Raleigh Cadent FT3 and the 20" Trek 7.6fx, I find one with a wheelbase of 1011mm and one with 1061. What is the effect of the longer wheelbase? Top tube lengths? What is the effect of changes in these various geometries?

Second question: how does one know what components are an upgrade over another manufacturer's bike? It is next to impossible to compare different manufacturers components let alone comparing within a manufacturer. For instance, which is better Shimano Deore or Shimano 443 or Shimano Deore or Tiagra? I looked at the Shimano website and without a pricelist in hand, it was not terribly informative.

The Raleigh is $100 or so less but I believe the components are better on the Trek. The Raleigh fits a bit better (I wish Trek had a 21" or worked in cm like the rest of the world) but last time I bought a Raleigh I really wished it better components on it.

Thanks for any wisdom imparted.

Did you go to this part of the Shimano site?
https://techdocs.shimano.com/techdocs/index.jsp

Cursor over the road or mountain group and you can see a list in descending order.
It doesn't really tell where road compares to mountain though.

I certainly wouldn't claim expertise in bicycle geometry and I'm sure you have to consider various factors beside wheel base etc. (the whole package)
However, think of a longer wheel base bike being like a bigger car. It'll ride a bit smoother, but handle a bit more sluggish. (or less "twitchy" if you prefer it that way)

1: top tube is the single most important measurement for proper bicycle fit. Typically you want your knees over or slightly behind the pedals at the 3'o'clock position of your pedal stroke. When the top tube is too long or too short you will be either stretched out or cramped on the bike. You then want to get the saddle tip to handlebar length to where you feel most comfortable by adjusting stem length and height. Having a stem that is too short or too long means the bike isn't fitting you right.

Wheel base: Longer wheelbase means more stability, so you get a less twitchy ride. Great for cruisers or touring. Bikes with a short wheelbase can be found on a more aggressive frame like road bikes.

2: Roughly in the order of highest to lowest...

Dura-Ace - XTR
Ultegra - (Deore) XT - Saint*
105 - (Deore) LX - Hone*
Tiagra - Deore
Sora - Alivio
2200 - Acera, Atlus

*Saint and Hone are downhill specialized.
Alivio, Acera, Atlus, Tourney, sora and 2200 and all are entry level products. They work fine, but don't bother upgrading them since it'll be cheaper to just buy a better bike with a better groupset on it.

I don't mean to become a component weenie but I like things to work - well. The best would be wasted on my abilities but things that don't work well tend to aggravate me. I rode a bike with Shimano shifters that had numbers in the window and I thought that was great for dyslexic people like me because I always shift the wrong way first and that gave it a much better visual for going the right way. Sadly, the bike did not perform to my satisfaction and moved up and lost the visual cue.

This Shimano page is much better than the one I found. Thank you.

The geometry thing is very interesting to me. The longer wheelbase being a cruiser but road bikes having a longer top tube means the magic is in the angles. I am going to check on my leg position before making my final decision tomorrow. The bike shop people are great but I have noticed that one person did not suggest I try the 22.5" when the 20" was a tad small because there were none in stock (found out later and I am making an assumption) and none has said that what would be best if I just got off my Trek kick and went to a manufacturer who framed for people built like me because they are a Trek shop or suggested taking the 57cm Pilot and beefing it up to be a hybrid, so.... the best bike shop is not substitute for doing your homework.

Well, the Rocky Mountain RC series is very similar to these offerings, the RC-50 would probably be around the same price range. Thats the only brand I can really personally recommend, as its the only one i've bought lately - but Rocky is a good manufacturer for certain.

As for those two, the Trek is one level above the Raleigh in the shimano componentry, as well as having a few additional things which could be considered over the Raleigh in spec (like carbon seatpost, seatstays), but the Raleigh is still made of reliable stuff.

AEO's componentry/geometry summary is good.

Fit is important enough that i'd rather ride Acera and fit the bike than XT and have to stretch or crane in order to ride. If that Trek isn't the best fit, looking for something else might be my advice.