Upgrade to rear mech on 1992 Raleigh Dynatech

[LateJunction]

I have just completed a refurb on my 1992 Raleigh Dynatech Encounter. I have the impression that the mechs really are end of life but I guess I won't be able to get a replacement 7 speed rear mech, will I? I assume that 8 speed is still available, but would an 8-speed cassette fit on the hub body? The hub is Exage on Mavic X618 NOS rim. See attached photos. It looks to me that there is a gap of about 4 to 6 mm between the largest sprocket and the ends of the spokes, which should be enough for another sprocket - yes? The gap between the dropouts is 130 mm.

If I can't fit an 8-speed cassette, and associated mech, what other options are there to renew/upgrade the rear?

 

[legrandefromage]

An 8spd cassette will not fit.

What rear mech do you have?

A '9spd' mech along with a 9spd chain will work lovely with your 7 spd set up

as will an '8spd' mech, 8spd chain

and a '7spd'

and a '6spd'

See where I'm going here? Lots of cross compatibility and plenty of spares via the site too.

 

[TOMAS]

Re:

When you say 'mechs end of life'... do you mean the rear mech or do you infact mean the cassette is worn out? As per above, your current hub/freehub will only allow for a 7 speed rear cassette. The gap is created as a result of a 'shoulder' machines on the freehub body to prevent the cassette contacting the spokes.

My recommendation is pick up a new chain, (7, 8 or 9 speed) and a new 7 speed cassette (loads available online/in shops (Evans clearance section for less than £10).

Welcome to world of Dynatech, I currently have 2 and am due to collect my 3rd Dynatech at the weekend

 

[LateJunction]

Re: Re:

When you say 'mechs end of life'... do you mean the rear mech or do you infact mean the cassette is worn out? As per above, your current hub/freehub will only allow for a 7 speed rear cassette. The gap is created as a result of a 'shoulder' machines on the freehub body to prevent the cassette contacting the spokes.

My recommendation is pick up a new chain, (7, 8 or 9 speed) and a new 7 speed cassette (loads available online/in shops (Evans clearance section for less than £10).

Welcome to world of Dynatech, I currently have 2 and am due to collect my 3rd Dynatech at the weekend

Sorry for delayed reply - been too busy. I meant that the rear mech is probably end of life. The cassette looks OK to me - some wear but nowhere near enough to warrant its replacement yet, although, as you say, they are not expensive. The real problem is a replacement rear mech. Finding a 7 speed compatible one is highly unlikely, even 8 speed are rare. Rare because I am looking for something with quality comparable to what I currently have - Deore Lx M550. So far I have found just 1 NOS Deore LX 9 speed M590 on Ebay, and it's the model without a bottle screw adjuster.

Thanks for the welcome to the world of Dynatech: I have been riding this one since 1991! I wish I could find another as a spare/backup but the ones I see have generally been horribly abused (by contrast everything on my bike is original, aside from the cables). I have a number of other bikes, including a 3 month old Boardman Hybrid Pro with a 1x11 drive train. It is a very quick, twitchy, bone shaking, uncomfortable ride, suitable only for velvet smooth roads (which is not my intended use case). The Dynatech by contrast, is heavy, stable and supremely comfortable on even rough cross country. And, given its 48-38-28 chainrings with 12-25 cassette on 26" wheel, it will still cover the ground on a good road plenty quick enough - I can probably sustain about 30 kmph on a flat road. Certainly it will readily hit 50 kmph on the downhill into my city centre - not far off my road bike (at 60 kmph = too scary, at my age!) . I just love this Dynatech.

 

[LateJunction]

An 8spd cassette will not fit.

What rear mech do you have?

A '9spd' mech along with a 9spd chain will work lovely with your 7 spd set up

as will an '8spd' mech, 8spd chain

and a '7spd'

and a '6spd'

See where I'm going here? Lots of cross compatibility and plenty of spares via the site too.

Thanks for this advice: as I said in reply to a later post, I want to replace the Deore Lx M550 rear mech with something of comparable quality. However, so far I have found just 1 NOS item on ebay - an M590 which is the design lacking the bottle screw adjuster. No 7 speed at all; no suitable quality 8 speed. But I had not though of looking on this forum for supply. I'm not keen on fitting a used item as I have no way of knowing what its history is and I'm probably not a good judge of the state of wear on a rear mech.

 

[legrandefromage]

Seems odd not to want to fit second hand, its not like your bike is new in its self either, its bonded, basically glued together and getting on a bit. An old rear mech isnt really going lose you anything.

Nice tidy rear mech

https://www.ebay.co.uk/itm/Shimano-Deor ... SwcUBYHmVr

And define 'end of their lives'? Excessive play, worn jockey wheels? I doubt if theres actually anything wrong with them - have you replaced the cable inners and outers? This always transforms shifting.

 

[CassidyAce]

Re:

At the very least, a secondhand rear derailleur would tide you over until you find a NOS replacement (which might take a while). And then you could keep the secondhand one as a spare. After all, they're only going to get more scarce in the future. And LGF is right: it's worth checking every bit of the cabling before you give up on the current derailleur.

 

[My_Teenage_Self]

keep an eye out for the XT 735 rear mech, very similar to yours, and much more abundant IMO.

 

[LateJunction]

Seems odd not to want to fit second hand, its not like your bike is new in its self either, its bonded, basically glued together and getting on a bit. An old rear mech isnt really going lose you anything.

Nice tidy rear mech

https://www.ebay.co.uk/itm/Shimano-Deor ... SwcUBYHmVr

And define 'end of their lives'? Excessive play, worn jockey wheels? I doubt if theres actually anything wrong with them - have you replaced the cable inners and outers? This always transforms shifting.

Yes, I agree the bike is far from new and, yes, I know it is glued together and that it is one of the few that has lasted so well. That's also why the respray I had last month cost so much money - but was so very well done that the bike looks new again, after looking VERY tired previously. That's one of the (irrational) reasons I would prefer to use NOS if I can.

'End of life' for the rear mech refers to the fact that the heads sheared off both limit screws some years ago after they became rusted in place. I had to have them drilled out and replaced with Allen-headed bolts, but I notice now that the Lo limit screw seems to have no effect. In addition, although for the most part, the indexing is OK, up and down, I found it hard to get things adjusted so that the mech holds the chain on the biggest sprocket on the cassette. One other thing that I don't like is that the rear mech seems mis-aligned with the chain. By that I mean the a plane through the two pulleys and their cage should be roughly parallel with a plane through the upper and lower runs of the chain - between the cassette and the chain-rings - when in a non-crossed over state. Mine is not - noticeably so, compared to that on my other 4 bikes. Inner and outer cables renewed throughout, of course, during bike refurb.

Thanks for the pointer to the rear mech on ebay. It continues to amaze me how an ebay search fails to identify the stuff that is really of interest to me. For example, it was only when I searched using just the term 'Shimano NOS' that I found anything of value.

 

[CassidyAce]

Re:

Yep. That would be a pretty conclusive account of why it's 'end of life'.