Chainring sizes and 8-speed cassettes

[elvisparsley]

Hello all
I got myself an old Trek 1000 the other day that looked lovely and shiny but the bike shop today pointed out to me the several missing teeth on the big ring, along with the shot-up chain and cassette. It's a Sora groupset, 52-39 at the front I think, with I think an 11-23 8-speed cassette on the back. All need replacing
I'm trying not to spend much on this, if anything, so looking around I wonder what my options are. Ideally I'd like smaller gearing at cheapest prices, in the very short term, cos she's not a keeper. What's the largest cassette I can use on the back, assuming I can't easily/cheaply get smaller at the front? Do I need to stick with 8-speed or can I go 9- or 10-speed?
Thanks in advance

 

[HLaB]

As you're not looking to spend I think you'll have to stick with the 8 sp to go more you'd need new shifters, etc. The size of the cassette you can have without spending more money is dependent I think on the size of your cage; at a guess (don't take my word for it) you could have at least a 27.

 

[zacklaws]

I've just replaced all my components which are identical to yours and the bill came to £49.90.

HG50 8spd 12-25 £24.29
Sora 39T double £9.45
Sora 7/8spd double 52T £16.16

I also bought a new chain which you will probably need if the teeth are missing or worn on the rings or sprocket and that came to about another £18. Shop around and you will probably get the same parts cheaper. I'm not sure if you got different make/pattern/groupset parts whether you may have to change front and/or rear deraileurs and even the shifters which would raise the cost.

Remember Sora is the cheapest Shimano groupset for road bikes

 

[elvisparsley]

Thanks- my friend now says he has an STX RC rear mech which would allow a larger cassette, say an 11-30. Would this work? Any bearing on the chain i would need?

 

[PpPete]

No worries - you need new chain anyway. Still an 8 speed.
Try this, almost certainly cheaper than buying individual new rings, that mech gives you the opton of this - pretty cheap & nasty but probably last a good while and one of these chains, may not be the lightest but KMC are usually pretty robust.

 

[HLaB]

Thanks- my friend now says he has an STX RC rear mech which would allow a larger cassette, say an 11-30. Would this work? Any bearing on the chain i would need?

I couldn't say for sure if it'll work, you can always give it a go but that a pretty big range for an 8sp, I'd think it be too big a gap between gears to be comfortable. Any 8 spd chain would be fine; I use SRAM as I like their quick link system (no tools needed).

 

[elvisparsley]

Wow. Thanks Pete. That's incredibly helpful. I might just go for all of that- works out really cheap!

 

[peanut]

if you are replacing both the front chainrings you might as well go for a 38tooth inner ring .Its the smallest ring which will fit a 130BCD and every little bit helps.


on the back you can buy a 11-32 9 speed MTB cassette very cheaply from Ribble cycles. Its silver despite the picture.
http://www.ribblecycles.co.uk/productdetail.asp?productcatalogue=SHIMCASM300
Take it apart and toss the 32 sprocket then rebuild the cassette with your original 8 speed cassette spacers as an 11-28t 8 speed for £15.00 .

your current setup 39x23 gives approx 46"
38tx28 will give approx 37" which is
an improvement of about 9" or about 3x gear changes

 

[elvisparsley]

Great advice all. I really appreciate it.
http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=11833
Would this be suitable? What is this Octalink business?

 

[jay clock]

Remember Sora is the cheapest Shimano groupset for road bikes

apart from the 2200 range which I have on my Trek 1.2. This was the replacement for the 1000 that the OP has bought and is a great all round road bike

 

[peanut]

Great advice all. I really appreciate it.
http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=11833
Would this be suitable? What is this Octalink business?

very cheap chainset which will do the job but you'll need to order and fit the special bottom bracket that fits it (Octalink) basically they are absolute rubbish and invariably end up being drilled out of your bike frame.

I believe you'll need to measure your frame's BB width to get the offset right for your chainset rings
Octalink has a unique spline which fits that particular chainset .
Do make sure that it is not supplied with steel chainrings. Sora used to use cheap heavy steel rings

 

[Rip Van]

Thanks- my friend now says he has an STX RC rear mech which would allow a larger cassette, say an 11-30. Would this work? Any bearing on the chain i would need?

I had shimano sora on a dawes giro 300. I fitted a cassette with largest sprocket of 30 (7 speed) and got away with it, which, along with the 39 tooth chain ring was good for any hills I'm near. The shimano sora rear derailleur on the dawes was made of plastic and eventually went tit's up. Replaced with Tiagra mech with 9 speed written on it, I got to thinking it wouldn't be too much work to upgrade to 9. Picked up second hand levers (mint luckily) on e-bay coupled with new compact (50/34) chainrings/9 speed chain. Total cost under £200 and didn't have to change the front mech. It's like a different bike.

 

[raindog]

I've got 8 speed Campag on my second bike. 50/39 chainwheels and 12-25 cassette. The short cage mech is fine with that and I can climb all the hills round here no problem.

 

[gbb]

Just been looking at my winter homebuild (first ride out this season)..
Sora mech, 11/28 cassette, Tiagra 53/39 chainset...the 28T on the back works fine.

I cant remember how many links are on the chain...i set it up with the Sheldon Brown method IIRC. If you're buying a new chain, you always get a few extra links anyway.

I seem to remember the cassette was cheap...at 28 or even 30T, there's not many people want them. Suited me fine to get on the road.

 

[elvisparsley]

Great advice everyone- thanks
Do you think I could get the above Sora Octalink crankset and just remove the chainrings from it and stick em on mine, since only the rings are in need of replacement?