Widest CX tyre to fit a roadie frame/caliper brakes

[ccr32]

I appreciate it may be a bit of a “how long is a piece of string” type question, but I am currently transforming a very rarely used Trek Lexa C (2013 I think) womens road bike into something of a hybrid for her to use mainly on the road but also around the pond and along the canal towpath.

The question I have is how wide can I go on the (700c) tyres before they start interfering with the frame, forks or brake calipers? Would like to get some very lightly nobbly CX types for it as the best kind of compromise. It’s currently on 700x23 road tyres.

[Your Dad]

Space between chainstays behind the BB will be a limiting factor, as will through the brake caliper. Measure both and you'll get an idea of how much mm you have to play with, but likely less than 28mm at the chainstays.

[Master Bean]

25mm Continental Grand Prix 4 Seasons would do for tow path use. They'll probably measure a bit wider depending on the rim width.

[Paul Drawmer]

I have a 2013 Endurace with Ultegra calipers. A 25 is fine, but a 26 needs adjusting the quick release + cable to get in and out of the calipers. It's a faff .

[Steve vRS]

I managed 28mm Conti 4 Seasons with 6800 Ultegra brake callipers but it was tight and would be dependant on the wheel as well I would think.

[lufbramatt]

Something like a 26 or 28mm panaracer gravelking would be ideal I expect.

[ccr32]

Thanks all. I’ll give some 28c’s a go and see how I get on.

[7 5 7]

(700 x 38C's) on my Franken CX/Gravel, but can get away with it more on vintage frames, not helpful for your question I guess ha!

[ccr32]

7 5 7 said:

(700 x 38C's) on my Franken CX/Gravel, but can get away with it more on vintage frames, not helpful for your question I guess ha!

Good to see what’s potentially doable though, so thanks!

[paulrockliffe]

You can use v-brakes from a kids bike if your brakes are the limiting factor.

[Your Dad]

paulrockliffe said:

You can use v-brakes from a kids bike if your brakes are the limiting factor.

Only if the current frame has twin pivot mounts, which it wouldn’t as it’s uses caliper brakes.

[ccr32]

Your Dad said:

paulrockliffe said:

You can use v-brakes from a kids bike if your brakes are the limiting factor.

Only if the current frame has twin pivot mounts, which it wouldn’t as it’s uses caliper brakes.

Indeed. Only has caliper mounts I’m afraid.

CheesecakeRunner said:

Will the frame take full mudguards? Then you can probably get a 30c cyclocross tyre in there.

If you’re near Birmingham, I’ve got a pair of hardly used 30c Schwalbe CX Comp in the garage you can have gratis.

Not sure about full mudguards - I guess it might? It’s got the eyelet mounts for them on the forks and frame.

Thanks for the offer but I am south east.

[seiben]

I just about squeezed a set of 32C Panaracer Gravel Kings on my retro winter bike, but in reality they were a touch too wide and ended up with sporadic rubbing either on the chainstays or the caliper pivots. I've since gone for a pair of 30C Vittoria Corsa something-or-others (a more wintery road-biased tyre) which fit much better.

Pic with the 32s:

[ArnageWRC]

The latest rim braked road bikes can take wider tyres; I've fitted 32mm GravelKing SK to a rim braked Domane SL, and a 30mm Schwalbe CX Pro for winter towpath rides....

However, as your bike is a 2013 model, you might struggle.