something for the twinshock trainspotters

Need help finding information or parts for that old machine in your shed? Someone in here will know!

Moderator: Moderators

David Lahey
Champion
Champion
Posts: 3530
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

something for the twinshock trainspotters

Postby David Lahey » Fri Sep 30, 2011 11:27 pm

I was doing a bit of tyre changing the other day and the one coming off (a 2002 Michelin tube-type XII rear) felt a bit heavier then the one going on (a 2006 IRC tube-type rear). I decided to weigh them and was amazed at the difference:
2002 Michelin XII tube-type rear 5.3kg
2006 IRC tube type 4kg
Thats a 1.3kg reduction in unsprung mass just by changing the rear tyre (they are both equally worn ie they have both lost their sharp edges) - gotta be the cheapest weight reduction of a bike I've ever seen.
I thought that maybe the weight difference is due to the age difference of the two tyres??? Do tyres get heavier with age??? Any ideas??


relax, nothing is under control

Will
C grade participant
C grade participant
Posts: 20
Joined: Tue Jun 28, 2011 11:27 pm

Re: something for the twinshock trainspotters

Postby Will » Sat Oct 01, 2011 2:30 am

More than likely something to do with carcass construction.... Does the Michie have heavier/stiffer side walls than the IRC ?
Might be a 6ply v 4ply thing ???



David Lahey
Champion
Champion
Posts: 3530
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Re: something for the twinshock trainspotters

Postby David Lahey » Sat Oct 01, 2011 10:17 am

I went and had a look for clues in the plies department
IRC tyre (the light one) is marked "4 P.R."
Michelin (the heavy one) is marked "2 polyester plies"


relax, nothing is under control

Jon V8
Expert participant
Expert participant
Posts: 209
Joined: Tue Dec 28, 2010 10:44 pm
Bike: Ty250,Ht5.
Club: Bath Classic
Location: Near Bath,SW UK.

Re: something for the twinshock trainspotters

Postby Jon V8 » Thu Oct 06, 2011 10:10 pm

I'm just in the middle of fitting a new IRC on the back of my Ariel and took note of how light it is compared to the old Pirelli...
David,do you have any other suggestions for massive weight loss on an HT5 ? :D



David Lahey
Champion
Champion
Posts: 3530
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Re: something for the twinshock trainspotters

Postby David Lahey » Thu Oct 06, 2011 10:40 pm

Jon you have me wanting to weigh a very old front trials tyre that came off my M49 Bultaco when I bought it. I remember the tyre felt quite heavy when it came off and I just couldn't throw it away. It has the vee pattern knobs like you can see on the sales brochure shots of 1960s Bultaco trials bikes. I'll weigh it on the weekend. Not saying your Ariel has 45 year old tyres its just as a matter of interest


relax, nothing is under control

Jon V8
Expert participant
Expert participant
Posts: 209
Joined: Tue Dec 28, 2010 10:44 pm
Bike: Ty250,Ht5.
Club: Bath Classic
Location: Near Bath,SW UK.

Re: something for the twinshock trainspotters

Postby Jon V8 » Fri Oct 07, 2011 6:26 pm

That tyre was so hard it could well have been 45 years old ! With new wheel bearings and a new tyre all I have to do now is make new footrest mounts and rear brake lever. Then it should be ready for a day of schooling by Mick Andrews tomorrow. :thumb:



David Lahey
Champion
Champion
Posts: 3530
Joined: Thu Jun 05, 2003 7:01 pm
Bike: Many Twinshocks
Club: CQTC Inc, RTC Inc
Location: Gladstone, Queensland

Re: something for the twinshock trainspotters

Postby David Lahey » Fri Oct 07, 2011 7:07 pm

Mick Andrews school? 8)

I just checked out that old front trials tyre and it is a Firestone made in Spain

Old Firestone front trials tyre 4.8 kg
New Michelin front trials tyre 3.6 kg
Attachments
P1010037.JPG
P1010036.JPG
P1010035.JPG
P1010034.JPG
P1010030.JPG


relax, nothing is under control

Jon V8
Expert participant
Expert participant
Posts: 209
Joined: Tue Dec 28, 2010 10:44 pm
Bike: Ty250,Ht5.
Club: Bath Classic
Location: Near Bath,SW UK.

Re: something for the twinshock trainspotters

Postby Jon V8 » Fri Oct 07, 2011 11:18 pm

I suppose the new ones must be "lead free" !!!
Mick Andrews is coming down to us for a day of schooling,organised by a mate in our club who knows him. Should be a day out to remember,plus learn something if possible...




Return to “Twinshock & Classic Trials”

Who is online

Users browsing this forum: Google [Bot] and 12 guests