Wanted: Help me climb!

Now folks........11-28.........Is it usable or are there too many big gaps if used with 52/39?

I'd say that's too many gaps for 8 speed. You've got a big jump between most of the mid range gears, so you'll always be struggling to find a gear that's just right, it'll either be too big or too low.

My understanding of Shimano/SRAM hub compatibility is that SRAM components fit on Shimano hubs and vice versa, so in theory it should work.

I put a cassette of similar ratio on my old MTB commuter a few years ago, I took it off after less than a week. As Andy says, too many gaps.

Just keep your eyes peeled for a 39T ring, the 39/23 combo should see you up most hills in the London area. I only run a compact (50/36) in the winter as I have dodgy knees, not helped by the fact that my left knee does a figure of 8 on each pedal stroke!

Cheers. I've compared it on sheldons gear chart and it definitely looks as though you miss some useful gears. Looks like I'm back on the hunt for 12-25 and a 39t ring...

I'd say that's too many gaps for 8 speed. You've got a big jump between most of the mid range gears, so you'll always be struggling to find a gear that's just right, it'll either be too big or too low.

My understanding of Shimano/SRAM hub compatibility is that SRAM components fit on Shimano hubs and vice versa, so in theory it should work.

This^

I'm not very versed in fishing components. But dont 9spd shimano cassettes fit 8spd shimano hubs?

If you went with a 55/39 (same jump as a compact), and a 13-25 (9spd). You get 111GI down to 41GI. Without big jumps.
This would be my chioce.

SRAM do a 12-26 (9spd), which would get you close to 39GI. Which I would consider good climbing fodder. Bigger jumps and a unusable high gear though.

Highpath do a 14-28, as well as costum options. I'd get in touch with them. Its quite possible they know more about setting your bike up well, without breaking the bank. Then we do.
http://www.highpath.net/highpath/cycles/plural.html

Gav, if you're still on the hunt for a 39 I think I have a 7400 chainring in that size lying around. I think that it is in fairly servicable state, though I haven't clapped eyes on it for a while. I'll have a hunt for it and let you know...

I find a 12-25 still too wide a gap - my take is to try for the 39 without doubt, 38 is even better, and an eg 14-25 cassette as the 14 is still quite high a gear with a 53 ring, unless you were racing.

(My preferred gears are triples where I can get 1 sprocket difference on the cassette in either 9 or 10 speed with the wide range the triple gives me- for clubruns etc you have a gear for everything- I'm no lightweight either :-( )