GT Tachyon drop bar mtb commuter

Hey everyone, I’m a long time lurker but now ready to jump in and share a build. I bought this bike ages ago thinking it was a road bike. It was the first bike I did a 100km ride on and I commuted on it for a while but when the original tyres wore out and I couldn’t find tyres in 700d I thought it was a lost cause.

Looking at diameters it seemed 650b wheels could be swapped out for the 700d but Sheldon Brown mentions tyres are not cross compatible. I had some spare tyres off my xc bike and thought Id give it a go anyway, and they fit up no problem. Unfortunately the 2.25 casing and big knobs on the Nobby Nicks only just clear the rear brake calliper and rub as the wheel flexes (the whole bike is super flexy). Besides, I’m hoping to do some ~mixed surface~ overnighters and would like something a bit faster.

So far I’ve beer can shimmed the seatpost so it doesn’t slip, removed all the reflectors, flipped the stem and replaced cables. Next step is to rebuild the brakes and maybe the hubs (maybe not they seem fine). I’ll be looking for some new tyres and probably some new bars, any recommendations? I’m thinking maybe Maxxxis Crossmarks could be good. Another option is getting some new rubber for the XC bike and putting the worn racing ralphs from that bike on this one. For bars I’m thinking some Soma Highway 1s, they’re just expensive to get shipped to AUS. Trying to keep it fun and cheap so I can shamelessly thrash and lock it up outside the shops stress free.

I’d be interested to hear what tyres people think might suit.

IMG_2066 by Clancy Bowman, on Flickr

Oops! Image links seem broken? Tried to insert them a different way but the link to flickr seems to be broken?

This is amazing

Relevant tyre discussion here


I have one, but it’s a flat bar 3x9 basket bike that spends 90% of it’s time hanging in storage unless I’m in town visiting.

If you want a shorter flipflop stem I believe user westcoastpete has my old one. No double ended quill but you have that bit already.

sirkev has one that he’s been trying to sell, complete and original.

definitely fits 650B tyres ok on those 700D rims. for what you’re doing, go thunder burt for looser gravel / singletrack / muddy or compass barlow pass or babyshoe pass / grand bois hetre for sealed/dirt/gravel.

Yup. PM if you want this stem.

Treadly Bikes in Adelaide have Soma HWY 1’s in stock. Think Commuter in Melbourne have them too, not sure about other states. Where are you located?

I’ve got a set of 42cm Hwy Ones to sell. PMd.


Yeah Clancy! Some overnighters with the Canberra crew coming up and this would be perfect. Maybe look at the specialized renegade in a 1.9?