Talk Morgan Forums Morgan Sports Cars Morgan Three Wheeler & Super 3 High grade of steel specialy made rear sprocket

Thank you MTWV2 for letting us know the costs and timescales. I think my only question now would be how the weight compares to that of the Supermax'd alloy version, which if I read it correctly is about 2.5kg?

Anyone know how heavy the MMC steel item is?

MMC Steel : 13.2 lb = 6 Kg
MMC Alloy : 6 lb = 2.7 Kg
Light Steel : 7 lb = 3.2 Kg

I don't know the weight of the supermax one

Just for the record, I have access to an alloy pulley complete with both guide rings so I popped it on the kitchen scales and it weighs exaclly 2.82Kg (6 lb 3 3/8oz or 6.22 lb). I guess it would weigh slightly less if it was Supermax'd due to metal being replaced by the poly material.

That's right. When I sent the pulley to Super Max, it came back weighing in at 4 lbs 12 oz. with a built in wheel side flange.

The mass is not the most crucial paramter, it is the moment of inertia that is most important for a wheel.
The further the mass is from the centre of the wheel, the more influential it is. This is governed by a square rule. There is therefore much more interest to me in reducing the amount of material near the rim than ornately removing material from the spokes near the axle.
In this sense the plastic refurb jobs become more appealing. As the outer material is less dense

back of the envelope calculations tell me that for a uniform sprocket, it has half as much energy in the form of rotational energy over and above what it had from its travel in a straight line.

The fact that these sprockets have most of their mass on the outside means the figure is likely to be greater. But its hard to tell without the cad file.


Anyone who is into pedal bikes knows that the shape of aluminium items are very different to steel even though they do the same thing. I see these steel sprockets have thin spokes and there fore must have a higher proportion of their mass on the outside.
hence the added weight of steel preludes to a much worse problem of weight distribution.

I wasn't overly concerned about the extra rotating mass and simply hoped that the extra unsprung mass wouldn't be noticeable on the road. It wasn't. On the track against a stopwatch it might make a difference but on the road...
When I raced bikes there were some people that reckoned that heavier wheels (so higher rotating mass) actually gave more progressive handling than the very trendy and expensive lightweight wheels when it came to how they spun up and then came back down to full grip from wheel spin. This being offset by the change to unsprung mass and all the strange gyroscopic effects on a leaning bike. In fairness this argument was mainly put forward by people that couldn't afford a set of Dymags.

I've now had a reply from SuperMax. The cost of the conversion is $535 but fully insured shiping to the UK is estimated at $100 taking the total to around $635 or £405.
Another consideration is that they don't have a mould for a 66 tooth overlay so they fit a 65 tooth one. I'm guessing that the change of gearing isn't noticable on the road although the engine will be working slightly harder. MichaelH?
Turnaround is around 3 days in the machine shop.


The emails sent via their website had ended up in their spam folder! Therefore, I advise using the direct email address for Vyvyan Ross supplied by MichaelH if you're interested.