Advice on gearing to suit my needs ......?

JimmyK

My bike is a trek 1000 8 speed racing bike with standard size double front chainrings and 12/25 rear cassette.Shifters are shimano sora type.

I have relapse and remitting multiple sclerosis and because of that, I can only push myself so hard. Using my bike as it stands, im averaging 18.5 - 19.0 mph over 40 to 60 mile trips , but..................some of my favoured routes can be quite steep in places.

I like to keep a constant cadence of 80 - 85 rpm , which is very comfortable , but on the more prolonged and hillier sections , having 12/25 at the rear and trying to keep a comfortable 80 - 85 rpm can mean that I run out of low gears. I am advised by my consultant NOT to be up out of the saddle and pushing and shoving up hills as I would like to be able to do.

I therefore have an expensive , but very comfortable saddle upon my bike, as I am on it for 100 % of my trips. I have been looking at lower geared Shimano 11 - 30 and 11 - 32T rear cassetes which would give lower gearing so as I dont raise my body temperature to relapse inducing levels . I know these are geared outside the limits of a road cassette , but am I right in thinking they are easily fitted to my trek 1000 racer ? I know also that I would need a longer throw derailleur , ( front, rear or both ? ) would anybody know which deraillure(s) I would need to look at ?

Have any of you any experience of using rear cassettes of these type on a racing bike for the lower gearing and am I right in thinking that converting over from 12/25 to say, 11 - 30 shouldnt be a complex job at all ?

thanks in advance for any advice.

Jimmy

Barteos

Many touring bikes use MTB rear derailleurs (mid or long cage) to accommodate larger cassettes (often 11-32T).
With a rear mountain bike mech you can practically use any cassette you want, even 11-34.
You may need a new chain though, as your existing one may be too short...

amaferanga

You may find the jumps between sprockets a bit big if you run a 11-32 cassette. Have you considered a triple chainset? Assuming your shifters will work with a triple (do Sora work with either a double or triple???) you'd need a new front mech and bottom bracket as well as the chainset, but it should only cost a little more if you shop around. You'd then have pretty much the same gearing that you have now if you stick to the middle and big chainring, but nice low climbing gears using the 30 tooth inner.

maddog 2

big range cassette = big jumps and a mtb mech needed

triple = lots of gears, small gaps but heavier/wider, uncooler

compact = two rings and lower gears

I'd say go 34/50 or 36/50 and a 12-25 or 12-27

John.T

I'd say go 34/50 or 36/50 and a 12-25 or 12-27

+1. Perhaps slightly more expensive than a wide cassette and MTB mech but much better to ride as you have more usable gears. A normal triple would only give one lower gear than a compact with the disadvantages that Maddog gave. He missed more complicated to use.

JimmyK

thanks for the advice guys.

rickhotrod

If you're not a fan of compacts, make a custom 13-29, 13-30, or 13-32 cassette or sell the bike and buy a triple.

John C.

The 8 speed cassettes are pretty basic so you don't have to go with the flow so to speak. Mix your cassettes up The cassettes are held togeather by 3 rivets, file the ends off and they come apart. If you have a 12-25 you could remove the 23 and fit a 30 giving you standard gears for the flat and then 21,25,30 for the hills. You would need a MTB cassette as a donor for the 30 ring and also a MTB rear mech. This does work, I've done it on one of my bikes.