Anyone have a Thorn ST 700 (4) fork? Tyre widths...

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Salade_Lyonnaise
Posts: 68
Joined: 21 Jun 2019, 11:18am

Anyone have a Thorn ST 700 (4) fork? Tyre widths...

Postby Salade_Lyonnaise » 8 Aug 2019, 11:36pm

Hello all,

I'm trying to establish max tyre width on a Thorn ST 700 (4) fork. SJS have said 35c with guards, but there are different max widths stated on some of the brochures - the 'mega brochure says both 38c and 40c with guards...

I'm wondering whether to purchase a pair, and wonder whether anyone has some, or experience using them who could help clear this up..I'm hoping to fit a 38mm or even 40mm (actual) tyre with guards, is this a push? I'd rather keep the bike safe than squeeze in something too tight, otherwise I'll look at other options.

Any thoughts appreciated!

PH
Posts: 7299
Joined: 21 Jan 2007, 12:31am
Location: Derby
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Re: Anyone have a Thorn ST 700 (4) fork? Tyre widths...

Postby PH » 9 Aug 2019, 9:49am

You'd think it'd be simple, but it's not. Tyre sizing varies wildly between models, they come up different depending on the rims, the guards also vary as does their fitting and peoples idea of what adequate guard clearance is differs. I've seen some Thorn bikes, straight from them, with guards fitted closer than I'd be happy riding. I have the 853 fork, it's quoted as being suitable for 35mm, a Marathon Supreme 35 fits fine, though on my rim it only measures 33, a genuine 35 with a deeper tread would be a squeeze and on muddy lanes I would expect it to clog. based on that and at a guess, I'd think the smallest size quoted, 35mm, is likely to be pretty much any tyre on any rim with most guards. Anything over that, I think you'd be taking a chance. IMO the only way you'll be 100% is if you find someone with the fork and the same tyre/rim/guard combination you're intending, or trying it for yourself - you risk the cost of postage, but Thorn have a reasonable returns policy.
OT - Thorn have some 531 touring forks on offer for £80, if these suit you they look like a good buy.
https://www.sjscycles.co.uk/forks/50-70 ... att-black/

Salade_Lyonnaise
Posts: 68
Joined: 21 Jun 2019, 11:18am

Re: Anyone have a Thorn ST 700 (4) fork? Tyre widths...

Postby Salade_Lyonnaise » 14 Aug 2019, 11:00am

Thanks PH,

That's really useful. I think I'm drawing a line at 38mm minimum — a shame as I saw those sale forks too, good deal! Thanks for the advice.