Recreational Cyclocross and Gravelbiking - 1984 Trek 620. Single Speed. Dumpster Dive Parts.
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11-18-11, 07:09 PM
I'm gonna race it tomorrow.
The rear brake isn't set up quite like I'd like, but that's ok. The relaxed geometry is bound to slow me down plenty.
11-19-11, 07:06 AM
11-19-11, 11:25 AM
The pedals match quite well!
11-19-11, 03:31 PM
well, the 144 BCD ring limited me to that 42T road chainring. The rough stuff on the single track pulled my wheel forward a bit and I dropped my chain twice on the race.... oh well. I think the wheels and drivetrain are going on to my 520, and my next race will be geared. Also I'll maybe train for more than 15 minutes and be sure that my bicycle is built more than 48 hours in advance!!!
The pedals worked well enough, I was able to clip in most of the time. being single sided isn't that great-- but this was a budget build. All told, I put about $400 into the bike, with either salvaged parts or new and used stuff from the good old LBS. I know I could have gotten a new SS 'cross bike for the same cash from Bikes Direct, but where's the fun in that?
11-19-11, 04:25 PM
Quick analysis of the frame angles looks as it the HTA is around 74 degrees, STA is 72 degrees. Handling really shouldnt be to slow. You might check the fork rake and determine the fork trail. If this was originally a dedicated loaded tourer, it might have have high rake fork and minimal trail. For unladed CX riding, might be better off with less rake on the fork, more trail for more neutral handling. Shoot for around 65mm trail??
Another custom/replacement fork with 1" more A-C for mud clearance would slacken the frame angles by about 1 degree and reduce the BB drop a bit for more pedal ground clearance.
That is one big frame. Probably works well to get the handlebars up high so long as you dont mind the reduced standover clearance.
Check to see if the read dropouts are worn. If they are thinned toward the front they dont hold placement as well, file them back to flat to reduce slippage and/or get a better skewer with more bite/teeth that will not slip on the dropouts.
THE seattube angle does not directly effect handeling of a bike and it looks like you could still slide the seat forward a bit if needed for a more aggressive CX position or even go with a zero offset seatpost for even more forward position, shorter effective TT. Long chainstays might be all that slow this bike from being as quick handeling.
11-19-11, 04:39 PM
I had a great time, and began to get used to it, but I think that this bike will donate its SS wheels and drivetrain to my '83 520 frame from the C&V frame trade thread.
I think this 620 will be set up for loaded touring, and I'll save up for an entry level newer geared 'Cross bike.
That dropout wear issue makes sense. *I was running the bike with nuts-- no QR. *The last minute adjusting I was doing to the rear brake might have led me to not retighten the wheel enough, either.
I'm just not enough of a beast to run SS on a cyclocross course. I'll take up a bit of running this summer to see if I can get those muscles in my lower back on par with my road riding muscles.
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