renton20

So I've been doing sandwich delivery on some roads here in minneapolis with a ****load of potholes. My back has been hurting and I was thinking that wider tires would help. I like Panaracer paselas but don't know how big I can go in the front. Anybody know if a 35mm would fit on the stock fork or if I should just drop the cash on a steamroller fork. Thanks

xkillemallx16

give tony an email before buying a new fork.

lac29

Just to update ... I emailed IRO and they said 28c tires are the max although I know this guy fit 32c CX tires (https://velospace.org/node/8684) but had to push the wheels a little farther out of the dropout to accommodate the tires.

jonathansmith68

I attempted to fit my Ritchey SpeedMax Cross 700x32's in my IRO Mark V fork and no go... I'd say, if you really want/need to fit larger than 28's, get the Steamroller fork. Just my two cents.

jgedwa

It depends also on how wide the rim is, but the tires I currently have on my Mark V are nominally 32s. There are even a few mm's to spare in all the pinchpoints. The closest, as I recall, is under the arms of the front brake.

jim

lac29

Do you guys think frame size changes whether or not you can fit 32s on the Mark V? I see that jonathan's is a 53cm and can't fit the 32c Ritchie Speedmax Cross while gyeswho's is a 59 cm (https://velospace.org/node/8684) and can fit the 32c Ritchie Speedmax Cross.

What size is your IRO Mark V jgedwa?

I have a 56cm Mark V and I really want to know if I should gamble on buying the 32c Ritchie Speedmax Cross tires. I'd like to have something fatter and with more treads to handle harsher road and winter conditions. Do they even sell 28c CX tires?

jgedwa

Mine is a big frame; 62cm

jtgotsjets

It would not make economic sense to equip the different sizes with totally different forks. I could see size affecting clearance in the rear, but not the front.

ETA: Here's a good source for thin CX tires
The Bike Biz

lac29

Thank you so much jt!

TheBikeRollsOn 

I think if your back is hurting then changing your tires might not help that much, maybe you need to change your fit. Raise saddle, longer/shorter stem, etc.

jonathansmith68

I apologize if I am bringing back an old thread but I was bored at work the other day and just thought I'd post my findings. I know that the OP was originally asking about tire clearances with regard to the fork, but after I failed to fit anything larger than a Ritchey 32c SpeedMax Cross tire (on Weinmann DP18's) in the stock IRO fork, I decided that I was going to go a different direction in order to achieve greater tire clearances on my Mark V. So the plan is to swap out the fork for something with more generous clearances. But first I wanted to check what was possible to fit in the rear stays. I was able to fit a 700x35c Bontrager knobby in the rear comfortably, and could probably fit as larger as a 37c or 38c tire. And that is with the wheel only about half-way back in the track-ends. That combined with something like a Steamroller fork and you've got basically a new bike that'll take in up to 700x37c/38c tires.

Check out some of the photos here: https://www.flickr.com/photos/jonatha...68/5239800429/

camashtorcal

Thanks Jonathan,
I have a Mark V Pro and was thinking of turning it into a steamroller with better tubing. I also had noticed the huge clearance in the rear and thought of doing this. I have a FBM sword fork though, I think max, I can fit a 35 up front.

jonathansmith68

Well, I ended up pulling the trigger on this idea and couldn't be happier. I can comfortably fit 700x35c tires in my Mark V, and it's now much more comfortable of a ride (due to the wider tires and a much less drastic saddle to bar drop). I'm jokingly calling this my "Comfort Track Bike".

You can find pictures of the tire clearances of the IRO Mark V frame and Surly Steamroller fork here: https://www.flickr.com/photos/jonatha...68/5595307929/ . Hope this helps you guys out. The switchover was super cheap, the fork retails for $89.99 at the LBS I work at and then I just got a relatively cheap Cane Creek headset (my old one was pitted out).

Renton 20, did you ever get something figured out as far as wider, more comfy tires go?

Also, camashtorcal, did you ever get your idea built up? Pics?

Squirrelli

Congrats on the new bike Jonathan! It looks fantastic.

Team IRO! <3

Build your own

One thing to keep in mind when trying to go big is that tiresizes are often not what they claim to be.Usually they are smaller, but it can go the other way as well.This can be a issue when going by what somebody else is using or when replacing a tire with another brand.For example, a 622-35 might be more like 31 in real life.I have some 44s that are actually 40mm,my 25 rubino pros are ~23.5,my 23 zaffiro pros are almost 25,my 630-32 michelins are 34,my 630-32 paselas where 26 and so on.Best bet when going for maximum fit is to use a combo that is known to work or try to measure in real life before buying online.

renton20

I ended up swapping for a surly pacer fork. A little less clearance, but exact same rake and within a few mm of a2c. I did tweak my fit which did wonders for my back, but what the fork was really great for was winter. I have a 62cm and was able to run a 35mm studded tire in front with a 32mm cross tire in the rear. Between the tire switch, surly open bars, and super low gearing(47x21) I was able to work without missing a day all winter. I highly recommend the pacer fork for anyone looking to run fatty tires.

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