29er MTB tyres

[Kirstie]

Anyone tried MTB 29er tyres on a Dawes Ultra frame? It looks like there might be enough clearance for one. Otherwise has anyone ever tried a slightly more knobbly tyre (eg a cyclocross tyre) for better off road grippage in the same frame?

I'm thinking of trying a 29er semi slick like the WTB vulpine...

 

[John the Monkey]

No direct experience myself, but;

Rims for 700c road tyres (actually ISO 622, i.e. rim diameter 622mm) and "29er" tyres are one and the same in terms of diameter, i.e. both fit tyres marked "700c" ... 29er rims are usually (currently) just strong touring rims in any case. The larger wheels are achieved by mounting a mountain-bike-width tire to a 700c diameter rim.

The truth has been altered from reality slightly in naming the big wheeled MTB variant. "29er" mimics the description of a 26" wheel (ISO 559, i.e. rim diameter 559mm) in stating the overall diameter of a typical 2" wide tyre sitting on the rim. 26ers are typically 26.2" in diameter, whereas 29ers are typically 28.5" in diameter but that doesn't sound as punchy as "29er".

The thing to be aware of - and as Muddyfox has hinted at above - is the fact that skinny road tyres and big fat knobbly 29er tyres can both (theoretically) fit on the same rim, so you should be sensible:

Don't put a 29er tyre on a narrow rim, nor a skinny road bike tyre on a "29er" rim (typically a rim 23mm+ wide).

Found here, http://domtbforum.proboards.com/index.cgi?board=general&action=display&thread=1353 although this seems to be the consensus on the internets looking at other sites.

Remember Sheldon Brown's tyre sizing chart (and its "safe rim/tyre width") table and you won't go far wrong, imo.

 

[Kirstie]

Ta - the rims I use are Rigida Chrina ie a big ol' touring rim (I believe). Will look into this further.

 

[John the Monkey]

Hmm - are there different flavours of the Chrina?

The only reference I could find to it indicated a max. tyre size of 32mm - (by way of comparison, my Mavic A319 will take a maximum 47mm tyre).

 

[andrew_s]

Chrina are a narrow rim, for tyres up to 28, or 32 at a push.
For 29er tyres you'd want a wider touring rim like the Sputnik, which suits 28mm or larger.

If you want the choice of narrow 23mm road tyres,and fat off-road tyres on the same wheel, you want the relatively uncommon 17mm (internal) rims. DRC19, or the Exal LX17 that Spa seem to have found.

 

[PpPete]

I've just (this evening) changed the Shwalbe Stelvio 25's on the Open Pro rims on my Galaxy for Schwalbe CX Pro 30. Utterly mad I know. I was going to put them on the Mavic T520 (A719) rims.... but I thought what the hell, let's try this.
Will report back tomorrow when I've tried them.

If it works - South Downs Way on Wednesday/Thursday.

 

[Kirstie]

Righto - so if it means a second set of wheels so I have the flexibility of off road touring as well then I might make the investment. Thanks everyone for your contributions - v helpful.

 

[PpPete]

Well....
Scwalbe CX Pro 30 are fine on Open Pro rims.... and thanks to Steve Austin for a previous link on them.

Not a single puncture despite some 100 km of very rough ground, sharp flints, etc. on South Downs Way.

Just one puncture on the OH's Conti Speed King 35 (on the original Weinmann Alesa rims)

Not entirely sure 25 y.o. Dawes Galaxys are quite the ideal mount for that particular route..... but hey, we had a lot of fun even though we ran out of time and didn't finish the route all the way to Winchester.

 

[John the Monkey]

Righto - so if it means a second set of wheels so I have the flexibility of off road touring as well then I might make the investment. Thanks everyone for your contributions - v helpful.

The wheels I just built are Mavic A319 on deore hubs - I like them a lot so far - tyre size 32 - 47mm, so they pick up where your chrina equipped wheels leave off, so to speak...