BT46 on Breganze 750 track bikes

Andy J

Andy J

Hero member
Location
Isle of Man
I need to change the 4 year old, but hardly worn, Avon AM22/23 tyres on my 840 twin to satisfy the latest 3 year maximum age rule for road racing. I was planning to fit ContiRoad Attacks, which I’ve used before on 500 twins, but can’t currently get hold of a rear. Apparently a pair of BT46 in the wanted sizes are available. As I can’t recall any experience of these tyres before what’s the view of riders that have used them on their 750?
 
sfcpiet said:
Very happy with the predecessor BT45 on track, BT46 should be at least equal.

Requires a fair bit more pressure than a regular bias-ply due to the soft side walls. 2.6bar front, 2.8 rear.

piet

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Tyre pressure with 2.6 and 2.8 is way too high. With the BT46 and a moderate weighing rider and lightened 750 and sunny condition 2.2-2.3 front and 2.1 rear, even less. For a dirty and cheap track session think of Maxxis Promaxx and Mitas MC 50.
 

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Andy J said:
I need to change the 4 year old, but hardly worn, Avon AM22/23 tyres on my 840 twin to satisfy the latest 3 year maximum age rule for road racing. I was planning to fit ContiRoad Attacks, which I’ve used before on 500 twins, but can’t currently get hold of a rear. Apparently a pair of BT46 in the wanted sizes are available. As I can’t recall any experience of these tyres before what’s the view of riders that have used them on their 750?
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What wanted sizes do you want? If using small 18" a pair of front 100 and 110 Contis with the 110 in rear reverse mode works nice
 
Agree the BT46 is a fine tyre, better than the BT45 which was more prone to cupping. The high pressures mentioned by Piet are for road use only, track indeed 2.0-2.2 range. I’m talking 750s here, bikes in the 170-200 kilos weight range. The biggest difference is that the compound in the middle is harder than the sides to extend tyre life, but it doesn't allow you to do incredible braking that the Avons used to give you. Also, the cantilever construction of the Avons allowed to use wide tyres on a narrow rim, the BT45 needs to be chosen more narrow, 100/90 front and 110/90 rear is indeed a safe choice.

Marnix
 
I don't manage to get enough heat into the tyres for such low pressures and feel uncomfortable with squirming tyres. Simply not aggressive enough. :rolleyes:

At least I can largely prevent the tread deformation on the front.

piet
 
Seen this track versus road pressure thing before, like Piet, I doubt I could get past the squirming low pressures feeling comfortably at all. I dont like it on the road, just 3 or 4 psi low. I check pressures before every ride.
 
Thanks for the comments/suggestions so far. I’m currently running 110 front and 130 rear on - AFAIK but I’ll check tomorrow - 2.15” front and 2.5” rear rims.
I will be racing the bike on the Billown circuit, which is a street circuit, with three long straights and several hard braking points. It’s also rained the last two years, so good grip in the wet is also a prerequisite!
 
The BT 45 front were starting to become that saw teth behavior after about 2 km, that was shit. The new BT 46 is a bit better, but I also feel similar shaking in the front at high speed curves over 120/140 Kmh. Conti do not do this at all but price is about twice as much. For touring, I am fine with the BT 46, for racing I do not know.
 
Fitted BT46 to my SFC, 100/90 and 120/90. They have only done track kms. Pressures I run were ftlbs, 27 rear 30 front.
Being the SFC I didn't push it as hard as I do the Motodd but still got on the gas. Scrubbed to the edges no worries and no shit in the pants moments either.
 
1 Atmosphere at sea level, I think, dont quote me. Semi-Metric. There are a few holdouts by tradition. Pascals never took off either, well, they did in Engineering but not in tyres. This is how my Structural Engineering lecture described a Kilonewton live load on a floor to mosty imperal people = 1 Arty Beetson per Square Meter. Arty Beetson was a 16-stone front row forward in Rugby League.
 
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