I know that there is at least one thread on the Diamondback Ascent, it however doesn't address my question(s). Several years ago I was given an "old" Diamondback Ascent (yellow frame & handlebars) by a friend who worked at a LBS. The previous owner had purchased it from a pawn shop and drove it to the shop to purchase a new bike.

A few years ago I'd replaced the cable, brake levers, shifters, chain and wheels. And then gave it to my now ex-girlfriend's daughter. Sadly she never rode it. And I added a pair of Specialized Flak Jacket Fatboys tires on it.

I'm not sure if the saddle is OEM or not (it's a back trails saddle), I'm pretty sure that the BB, front and rear derailleurs and headset are. After my Seek and Hardrock were stolen they returned the bike to me and I've been using it to get around the neighborhood. And would like to further upgrade/convert it to a commuter/touring bike.

To that end, what size BB does it have, what is the largest cog count cassette can I put on it. I suppose putting a pair of 700 rims on it is out of the question.

The only things I still need to add to it are fenders and racks/bags.

The BB and cog size questions are directly related to your components.

You'd have to use the appropriate sized BB for whatever crankset you have on the bike.

The largest cog you can have is determined by your derailleur- it depends on how low the upper pulley can rotate downward without rolling on the cog.

The most amount of cogs is determined by your cassette/hub/freewheel. It's also dependent on your shifters- if you've got indexed (clicky) shifters, they should match how many cogs you have. If you're running friction, you can use as many cogs as you can reliably shift to (if your shifter allows it).

The 700C question is determined (mostly) by your frame clearance and the reach of your brakes. If the wheel doesn't clear your brake bridge, chainstay bridge or the fork crown... it just won't go. If your bike has cantilever brakes, they're probably mounted too low to be adjusted up to 700C. If you have sidepulls, you may need to get longer reach brakes.


So the answer to all your questions is "it depends."

My 1988 or 1989 Ascent uses a 68mm English-threaded BB, and like [MENTION=174646]The Golden Boy[/MENTION] mentions, its length will depend on the crank you want to use. Since mine is a fixed-gear, it's wearing a 104mm BB. YMMV. The bike would have originally had a triple on it, and an RD that would handle at least a 28T cog.

There would be very little point in converting to 700C, even if you "could", since there are really good options in ISO 559 (26") tires.

700s are a no go- its a 26" mtb with canti studs on the frame and fork.
The bottom bracket is either 68 or 73 wide. My 2 Ascent frames(90 and 91) are both 73 wide, but dont know for sure for yours since if I am thinking of the frame, yours is older and may be 68 wide. You can simply measure or pull the spindle and check what is stamped on it.

As for changing the crank to something different- a warning- The Ascent had different sized chainstays thru the years from year to year and as a result, you need to get a crank that will fit in the chainstays. Not all cranks will.
What gearing do you have and what do you want to change it to?

For the freewheel(guessing its a freewheel), as mentioned, that limitation is based on your rear derauilleur and how much chain it can eat up when using the smaller cogs.

Thank you, right now for the rear it's indexed and for the front it's friction.

It has cantilever brakes on it.

It still does have a triple on it.

Okay, I kind of figured that 700s would be out of the question, but figured that it wouldn't hurt to ask.

I'm just looking to get some more speed out of it. When I get home tonight I'll look at the rear wheel and the triple and post later. As well as take some pictures of it to post.

I was chatting with one of Diamondback's reps the other day and they couldn't tell me how old it was even with the serial number. Is there any other way to figure out how old it is? Also I am missing the dust cover on the non-driveside crank.

You can look up component date codes at vintage-trek.com and look on the left for component code dates. Find the parts that are original & look on the backs of them to find the codes. Then search from there.

What did you say the original parts are? We can probably help you out.

Like speed on streets?

Get some non-knobby tires. That's the first step.

Next thing I'd do is look for a different freewheel with gearing like you need (assuming the bike has a freewheel, not cassette and freehub)

When I was riding my MTB as my primary bike, I always felt like I was spinning out the high gears- MTBs are geared pretty low

I'm pretty sure that the BB, the front and rear derailleur, handlebar and headset, cranks are, as well as the front triple. The brake levers, sifters, cables, chain and wheels have been replaced "recently" by me.

Yes, it's taking me longer to cover the same distances. Which is somewhat understandable going from a 27-speed to a 15-speed.

I'm running Specialized Flak Jack Fatboys rated at 100psi. Saw that Continental has some tires that are 26"x1.18" rated at up to 120psi:

[TABLE="class: dataTable no-footer"]
[TR="class: odd"]
[TH="class: ci-nowrap"]0118365[/TH]
[TH="class: first-column-addition"]
[/TH]
[TD="class: ci-nowrap"]28-559[/TD]
[TD="class: ci-nowrap"]26 x 1 1/8[/TD]
[TD]PolyX Breaker[/TD]
[TD]black/black Skin[/TD]
[TD]3/180[/TD]
[TD="class: ci-nowrap"]320[/TD]
[TD="class: ci-nowrap control"]95-120
[/TD]
[/TR]
[/TABLE]

I'm gonna look around and see if I can find anyone who carries them locally and buy a pair of them.

Okay, dumb question how do I tell which I have?!?

I'm think that that is a big part of the difference, in going from a 27-speed bike to a 15-speed bike that the ratios are different. How does one go about figuring the ratios?

Being as I am converting it to a commuter and it will never (yes, I know about never saying never, but in this case I can say that) go off road. Other then in the grass at the local parks to avoid the iPod zombies, or the local rail-to-trails it will never be taken off road. So I do not mind changing the ratio to give me more speed.

The amount of gears doesn't matter a whole lot. The 27 to 15 speed only matters as your steps between gears are smaller, not that your top end is faster.

Your rear end only has a 5 speed freewheel? That doesn't seem right- I think the Ascent would have come out in the 6-7 speed era.

IMO- a 1.25-1.75 tire would be preferable- and I don't think I'd want a tire on a commuter up at 120psi.

My taint hurts just thinking about riding a 120psi tire. On any bike.

@Digital_Cowboy, I take my Ascent over 30 MPH all the time, and that's on 1.75" tires with 40psi or less in them -- how fast do you need to go?

Yes, and that is what the original shiftier had marked on it as well. I think that personally even a 7-speed would be a welcomed change.

On my Seek I was running 116PSI and loved it. Nice and hard and nice and fast and could corner.

I can understand that for some that that would be "uncomfortable." And I also understand/realize that for all intent and purposes that I'd be riding on the "balloon" equivalent of hard rubber/tubeless tires.

On my bikes that were stolen I was usually traveling at the slowest in the 15 - 20MPH range and at the fastest in the 20 - 25MPH range, sprinting up towards 30MPH, consistently, and would like to get back there. As right now it's more like the 10 - 15MPH range.

I also understand that probably part of the problem is that I don't yet have clipless pedals on this bike, yet. When I do I'll upgrade to clipless pedals it'll probably be to Eggbeaters.

But overall I'm not too displeased with this particular bike. Just have some tweaks to make to it. And again, yes, I know that they're not all going to necessarily be what someone else might do. But, isn't that part of the fun? Making our bikes OUR bikes?!?

A short while ago I happened to notice that when I put the new brake levers on that I put them on upside down. Oh, well they still work and stop the bike.