Shimano Alivio update

Pyebird

Hi everyone, I'm here after scouring Google for answers and so far have not obtained enough solid info to give me the confidence to go out and buy what i need. I have a 21spd Alivio Dawes Omega that I purchased new back in 1993/4 that I'd like to keep going a while longer rather than . It's predominately been a road bike over the years and was partially revived a few years ago for a charity triathlon. It's had Deore XT V brakes fitted with Shimano ST-EF65-7R shift/brake levers & some Schwalbe road tyres to keep it going but the gears are due a replacement as they skip. I'm aiming to replace the cassette, both derailleurs & the triple crankset. The hubs & bottom bracket have very minimal play in them and there's no rumbling when spun so seems sensible to retain these. Looking at the Shimano archive catalogue the rear hub is an FH-MC12, the cassette is a CS-IG50 & the bottom bracket a BB-LP26.

My problem is that when searching for new 7sp parts not a lot comes up. I've read numerous posts that say that i can use an 8/9 speed rear derailleur with a 7spd cassette & numerous posts that say it's not possible. Can anyone advise on what 7sp cassette/derailleurs will work together and fit my hub? I'm going down the 7spd route simply because i have relatively recently replaced the shifters but if changing everything to 8spd+ is the sensible way to go then i'll swap the the lot. Also & as I'll be using this mainly on the road then when i replace the crankset I'd like to increase the size of the large ring on what i currently have to up the top end speed. Again the shifters are for a triple ring so sticking to a triple ring is preferable although not set in stone.

Whilst i appreciate that even the basic entry level kit nowadays is still an improvement on what i currently have i'd like to up the spec a little but keeping the spend to a sensible level. I'll be using the bike to shed some weight and get my fitness back so I'm not too worried about ending up with a Frankenstein bike. If i stick to it and achieve my targets then I can justify treating myself to a new bike. Hopefully I've provided enough info for someone to advise suitable replacements but please let me know if I've missed anything. Now, over to you lovely people.

The Rookie

5,6,7,8 and 9 speed derailleurs all use the same pull ratio, you can use the rear derailleurs interchangeably and I often have.
Latest 9 speed Alivio is a great value item and a useful upgrade from yours.

As for your hub, is it spin on freewheel or freehub with removable cassette, if its the later you can upgrade to 8 speed by using 8 of the 9 gears from a 9 speed cassette and a nine speed shifter (last click does nothing), did that on my daughters Uni commuter hack.

Pyebird

Thanks The Rookie & apologies for the late reply. I've yet to attempt taking the cassette off but searching the part & patent numbers of the hub pretty much all show it as a freehub with removable cassette. If i do indeed replace the cassette, derailleur & shifter with 9sp components then would all 9 gears be usable or is there a reason why it would be limited to 8? Also, am i free to replace the triple crankset with any Shimano item so long as it has a square taper rather than splined? I'm assuming that there is/was only 1 size of square taper?

The Rookie

A true 7 speed freehub is narrower than that used for 8,9,10 and 11 speed, sometimes a 21 speed bike like yours will have a 7 speed cassette and a spacer onto an 8 speed hub (so is easy to convert to 8,9 10 or 11 speed), sometimes it will use a narrower 7 speed hub, if its the latter you are stuck with 7 speed apart from the 'bodge' I detailed.

As for the cranks, yes pretty much as MOST Shimano are 122mm BB axle, however some are not so you need to check the Shimano tech docs site for your current and proposed parts to make sure they are compatible.

steve_sordy

Shimano Technical Documents

http://si.shimano.com/#/

It is not particularly user friendly.