Quick update on my Trek 4500 → gravel conversion.
While test-fitting the rear wheel, I noticed the tire clearance was extremely tight. There was barely any space between the tire and the frame, and it was rubbing under load.
To fix this, I lightly sanded a small area of the frame where the tire was contacting it. I removed only a minimal amount of material — just enough to gain some clearance and stop the rubbing, and only in the problem area.
After that, I sealed the area with metal epoxy, mainly to prevent water from getting into the frame and to protect that spot.
Now the rear wheel spins freely, and the clearance is much better for my current setup.
I know sanding a frame can be controversial 😅, but in this case it was a very small adjustment, and I’ll keep an eye on it over time.
Next steps:
• More test rides
• Fine-tuning the setup
• Deciding whether to keep this tire size or go slightly narrower
As always, feedback and experiences from people who’ve done similar MTB → gravel conversions are very welcome! 🚴♂️💬
by zizas2
7 Comments
That is still not enough clearance…ride on any type of small pebbles and they will shoot and get stuck in there, let alone on real gravel or mtb
Why bother? Just let the tire do the sanding.
Just go 650b if originally 29r or go 26 if it was originally 27.5.
What tyres will you use?
Salt is the killer of aluminum frames, so if no salt contact open bolt holes is fine
Thank you for posting this cautionary tale. I was debating on running about 3 mm clearance on my road bike. I will be downsizing tires now.
I converted an old Trek 4300 to a gravel bike about a year ago. I used 650b x 47mm tires and have a few mm of clearance to spare. I am moving to 27.5” x 2.1” tires and I am nervous about clearance 😬. I don’t think I would try 700c wheels but good luck!
I am following to see what you do with the bars and levers. Wife wants drop bars on her hardtail Talon so I ordered the redshift kitchen sink bars before considering if I would need to switch to brifters. I think the mtb shifter and levers will fit on edge of the flats …
I love when people rescue old frames, do conversions, modify things, etc. Because bikes are cool.
But I also love bikes that work and/or would be nice to ride so a lot of the time I wince at these projects too.
This one gets a wince.