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Old 03-04-17, 02:06 PM   #1
masterchief
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Commuter-tourer Trek 520 build advice/sanity check

I'm looking for comments and general advice and opinions on my upcoming build, see the spec below.

Background:
I want to build myself a good quality daily commuter that I can also go touring on for a couple of weeks in the summer. I'm a reasonably skilled home mechanic, I build my road bike last spring from the frame and up, and I'm learning to do handbuild wheels as well. My daily commute is 30 mins on bike each way with a few hills in between, and I use my bike for almost everything. My girlfriend and I want to go touring here in Europe for some weeks in the summer, mainly on paved roads.

My spec so far:
Frame + fork - The Trek 520 geometry appeals to me, and since my lbs can get the lovely green canti/v-brake version frame for me, that is the frame I'm basing this on. The LHT has been on my list as well, but I wont be needing the extra tire clearance, and I like the 520 geometry better.

Hubs - Deore LX T670 front + rear
Rims - DT Swiss TK 540 32h (maybe a 36h rear)
Spokes - DT Competition
Tires - Panaracer Pasela PT, 32c or 35c.

Shifters - Tiagra ST-4700 2x10 speed
Rear derailer - Deore RD-T610
Front derailer - Tiagra FD-4700, I have one laying around, but I'm honestly not sure if it will work with the 38-24t rings of the deore crankset, when it's intended for road size rings. But then agian, the difference between the 38t and 24t rings is not far from the difference in a compact 50-34t set, so it might work.
Crankset - Deore FC-M617 38-24t
Cassette - Tiagra CS-HG500 11-32
Chain - KMC x-10
Bottom Bracket - Deore SM-BB52
Cables - Jagwire Road Pro
Brakes - Tektro rx-5 mini v

Headset - Ritchey Comp Logic
Handlebar - FSA Vero
Stem - Ritchey Comp 4-axis
Seatpost - Ritchey Comp 2 bolt
Saddle - Charge Spoon

Fenders - SKS Longboards
Rack - Tubus Logo or Cargo

I have been genuinly impressed with the compination of Tiagra 4700 STI levers and Tektro rx-5 mini v brakes on my road bike, which is why I want to use them again in this build.

I'm looking for any comments and opinions on why this is or isn't a good spec.

Thanks.
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Old 03-04-17, 02:11 PM   #2
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One of my friends commutes * on a Trek 520, didn't really change much from stock, other than add top mount levers and Mudguards

Its pretty much like the current edition.. Mudguards : Planet Bike Grasshopper . its a Bamboo Laminate , super rugged..

* He comes in from where ever the space for his motor home parks, he goes south for the winter, comes back in summer to help out @ LBS.
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Old 03-04-17, 02:14 PM   #3
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I like the build and I think the 38/24 upfront is a clever idea but I'd go with a triple even if that means having to ditch the brifters. I'd also be tempted to go 11/34 in the rear.
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Old 03-04-17, 02:28 PM   #4
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I like the build and I think the 38/24 upfront is a clever idea but I'd go with a triple even if that means having to ditch the brifters. I'd also be tempted to go 11/34 in the rear.
Thanks, I run a triple on my current commuter, but I want to simplify things and be able to use the 38t ring as the primary chainring. I currently find myself shifting very often between the big and middle ring.

11-34t in the back is noted, it's the reason i'm going with the deore rear derailer, since it will accept the 34t in contrast to the long cage tiagra rear derailer. I'm not all set on gearing yet, I've been thinking 38 was too low as well, but I think i'll try this out and see how it goes.
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Old 03-04-17, 02:58 PM   #5
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Aren't the 4700 shifters the newest ones, not compatible with much other 10 speed stuff? I'd double check whether that RD will work with them.
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Old 03-04-17, 04:12 PM   #6
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Are you sure that a 38T chainring is big enough (with 11/32 cassette) for flat riding or shallow downhills? I use a 11/32 cassette on several bikes, my derailleur touring bike has a big ring of 46T (triple, 46/42/24) with that cassette.

Not sure if the fenders will fit under the mini-V brakes. I have mini-V brakes on my folding bike, but that is the only bike I do not have fenders on so my experience with mini-Vs is limited. My other rim brake bikes that have fenders have full size V or cantilever brakes.
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Old 03-04-17, 04:30 PM   #7
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Quote:
Originally Posted by masterchief View Post
I'm looking for any comments and opinions on why this is or isn't a good spec.
No go on that rear derailleur with the shifters you want.

But with the gearing you list, you can just use the Tiagra 4700GS rear derailleur.

4700 shifters need 4700 derailleurs. Same with current 105 shifters- they wont work with mtb or lower # derailleurs. Its what Shimano has steadily moved toward with any current STI shifters that have cable routing under the tape.
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Old 03-04-17, 05:17 PM   #8
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masterchief, With an 11-34T cassette you'll have a range of ~20-93 GI, certainly do-able. If you can find 4600 generation STI levers and FD, you can use your desired RD. If you are not going to load the front of the 520 too heavily, 32 hole rims will work with the 36 hole rears.

Brad
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Old 03-04-17, 06:09 PM   #9
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Being a big fan of triple chain rings. On a retired Touring bike I changed from the 50/39/30 to a 50/39/24 it is now my city commuter, 11/32 cassette. Works surprisingly good.
I like the 520, near bought one this past fall. A good test ride revealed my dislike for bar-end shifters.

Enjoy your build.

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Old 03-04-17, 07:22 PM   #10
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Can you purchase just the 520 frame and fork from Trek and may I ask your cost if you don't me poking my nose in here?
Btw, your 38x11 at 90 rpm's is maxed out at 25 mph which may or may not be fast enough for you. I would want at least a 42 big ring up front and that can easily be done with a mountain bike crank, of which you can remove a chainring if you want to maintain a double up front.
Best of luck with your build.
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Old 03-05-17, 05:45 AM   #11
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Thanks for all the comments and good advice!

Quote:
Originally Posted by shelbyfv View Post
Aren't the 4700 shifters the newest ones, not compatible with much other 10 speed stuff? I'd double check whether that RD will work with them.
Quote:
Originally Posted by mstateglfr View Post
No go on that rear derailleur with the shifters you want.

But with the gearing you list, you can just use the Tiagra 4700GS rear derailleur.

4700 shifters need 4700 derailleurs. Same with current 105 shifters- they wont work with mtb or lower # derailleurs. Its what Shimano has steadily moved toward with any current STI shifters that have cable routing under the tape.
Quote:
Originally Posted by bradtx View Post
masterchief, With an 11-34T cassette you'll have a range of ~20-93 GI, certainly do-able. If you can find 4600 generation STI levers and FD, you can use your desired RD. If you are not going to load the front of the 520 too heavily, 32 hole rims will work with the 36 hole rears.

Brad
Okay so I've done some more research and it seems you guys are right, the st-4700 will not work with the T610 rear derailer. I was under the impression that up to and including 10 speed, Shimano road and mtb shifters and derialers were interchangeable (except from the dyna-sys mtb range, which the t610 is not part of, as far as I know). This is almost correct, as bradtx says if I would use the older 10 speed Tiagra 4600 shifters, it would work, BUT Shimano has used the cable pull ratios of the new 11 speed on the 4700 Tiagra (and maybe also the R3000 Sora) group, so the st-4700 will not work with the t610 rear derailer. Thats a bummer, as I was opting for the t610 to be able to use a 34t cassette if I wanted to. With the Tiagra 4700 rear derailer im limited to a 32t cassette, which may be fine, but I like having options. Anyway, thanks for making me aware of this, that was exactly the reason I posted here.

Quote:
Originally Posted by Tourist in MSN View Post
Are you sure that a 38T chainring is big enough (with 11/32 cassette) for flat riding or shallow downhills? I use a 11/32 cassette on several bikes, my derailleur touring bike has a big ring of 46T (triple, 46/42/24) with that cassette.

Not sure if the fenders will fit under the mini-V brakes. I have mini-V brakes on my folding bike, but that is the only bike I do not have fenders on so my experience with mini-Vs is limited. My other rim brake bikes that have fenders have full size V or cantilever brakes.
Quote:
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Can you purchase just the 520 frame and fork from Trek and may I ask your cost if you don't me poking my nose in here?
Btw, your 38x11 at 90 rpm's is maxed out at 25 mph which may or may not be fast enough for you. I would want at least a 42 big ring up front and that can easily be done with a mountain bike crank, of which you can remove a chainring if you want to maintain a double up front.
Best of luck with your build.
I've been comparing gear inch ratios of my current commuter triple setup with this build, and it looks like the 38-24t will cover my needs, although I did think of it as vey small to begin with. I will have to see, and if its too low a 40 or 42t is available online. 25 mph is plenty for my commuting, I don't mind coasting at those speeds. I actually think a lot of peoples bikes a way over geared for their purpose. How often do you find your self commuting/touring at 25 mph? For me thats not very often, so I would rather have a wide range for the cruising and climbing speeds.

Regarding the mini-v's and fenders it wont be an issue. I have the same setup on my road bike for spring and autumn weather, see the attached picture. The tire is the Panaracer Gravelking 32c (file tread version) on a DT Swiss R460 rim, and there is plenty of clearance for road riding.

After the 520 caught my attention, I emailed the four Trek dealers in my town, and they would all be able to make a special order and supply it within a week. The price is 3800 danish kroner for a frame with fork, which with current exchange rates is $543. I have no idea if that sounds expensive to an american, but the build in total should land around $1500, which is within my budget.
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Old 03-05-17, 06:06 AM   #12
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masterchief, With the 32T bottom sprocket you'll only lose ~1.5 GI in the granny. Still a do-able combination and easier to source. Once up and running you may want to experiment with a 34T bottom sprocket and/or a smaller inner chain ring, if really desired. A 22T inner chain ring with the 32T bottom sprocket will develope ~18.5 GI.

Brad

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Old 03-05-17, 06:37 AM   #13
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4600 shifters are still available Shimano STI Levers Tiagra 4600 - 10 Speed - Gear Levers and Shifters - Ribble Cycles Maybe still some 5700 if you search. Your price for the frame and fork sounds very reasonable!
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Old 03-05-17, 08:35 AM   #14
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Okay so I've done some more research and it seems you guys are right, the st-4700 will not work with the T610 rear derailer. I was under the impression that up to and including 10 speed, Shimano road and mtb shifters and derialers were interchangeable (except from the dyna-sys mtb range, which the t610 is not part of, as far as I know). This is almost correct, as bradtx says if I would use the older 10 speed Tiagra 4600 shifters, it would work, BUT Shimano has used the cable pull ratios of the new 11 speed on the 4700 Tiagra (and maybe also the R3000 Sora) group, so the st-4700 will not work with the t610 rear derailer. Thats a bummer, as I was opting for the t610 to be able to use a 34t cassette if I wanted to. With the Tiagra 4700 rear derailer im limited to a 32t cassette, which may be fine, but I like having options. Anyway, thanks for making me aware of this, that was exactly the reason I posted here.

Tiagra 4700GS will handle a 34t cog on the cassette per Shimano's website.
Also, Shimano is conservative with estimates. For example, some are able to fit 11-36t cassettes matched to new 5800 rear derailleurs which are spec'd to handle a 32t cog at largest.

Regardless though, a 34t cog will work fine with 4700 as the seystem was made to handle 11-34.
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Old 03-05-17, 09:41 AM   #15
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Yeah I've read before that Shimano is on the conservative side, so maybe you're right about the 34t cog.

This whole thing has got me wondering about the front shifting as well. The chainline should not be an issue with the 135mm deore rear hub and the deore crankset, if I'm not totally mistaken, they're kind of made for each other?
But, I'm starting to worry that the FD-4700 front derailer won't work with the deore crankset for two reasons:
1. The chainline, which will be wider that a road double, so I'm afraid the derailer wont be able to shift to the big ring even with the limit screw all the way out.
2. The derailer cage will hit the chainstay when in the small ring. I can moven the mouting point up the seat tube, but will that not affect the shifting negatively?

I've read that the Shimano cx70 front derailer could be a solution to this, since its aimed at the smaller cyclocross chainrings. I'm currently using the cx70 front derailer on my road bike, since it comes in a top pull version, and it works with the ST-4700.
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Old 03-05-17, 09:55 AM   #16
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I commented that I thought that the 38T chainring for a big ring was too small, you responded:

Quote:
Originally Posted by masterchief View Post
...
I've been comparing gear inch ratios of my current commuter triple setup with this build, and it looks like the 38-24t will cover my needs, although I did think of it as vey small to begin with. I will have to see, and if its too low a 40 or 42t is available online. 25 mph is plenty for my commuting, I don't mind coasting at those speeds. I actually think a lot of peoples bikes a way over geared for their purpose. How often do you find your self commuting/touring at 25 mph? For me thats not very often, so I would rather have a wide range for the cruising and climbing speeds.
...
On several tours I have gone for long distances (tens of miiles) on shallow downhills where I was pedaling at a low cadence and low level of effort in my highest gears at speeds near 25 mph because I really hate to just sit and coast for long periods of time. Pedaling takes some pressure off my bum and keeps my legs from getting stiff. But, if you prefer to coast, perhaps the 38 will be perfect for you.

I also use a chain catcher to prevent me from dropping the chain on downshifts. You might consider that, they are cheap and once installed are something you never have to think about again.
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Old 03-05-17, 10:06 AM   #17
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Yeah I've read before that Shimano is on the conservative side, so maybe you're right about the 34t cog.
The site actualy states 34t is stock acceptable. So being conservative, you could actually probably get a 36t to work.
You wouldnt be pushing it with a 34t as thats what its made to handle.
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Old 03-05-17, 10:30 AM   #18
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Before I mentioned that a 38x11t will get you 25mph but at 90 rpm. Most cyclist don't pull 90 rpm like a professional, most of us fall into that 60- 80 rpm range so even using 80 rpm you're now looking at 22 mph max and I'll bet there are days on the flats with some wind at your back that you would enjoy a little more resistance from those pedals. Just sayin'
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Old 03-06-17, 04:24 AM   #19
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I'm going with the 38t chainring as I think it will be suitable gearing wise, but I will swap it for a larger one at some point if the 38t is not sufficient, as some of you predict.

My worries is regarding the 4700 road front derailers ability to shift the chain between smaller chainrings than it was intended to, but since I all ready have the 4700 I guess I'll just try it out, and then get the cx70 if the 4700 doesnt work.
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Old 03-06-17, 06:50 AM   #20
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I use 40-26 up front with a tiagra FD and it works well. I also use a 12-36 cassette with an older 105 long cage rd. I have older tiagra shifters and it all seems to work.

I think what u propose sounds real workable.
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Old 03-18-17, 08:37 AM   #21
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Thought I would upate my progress on this build for those interrested. Will also post a picture of the finished result in the Trek 520 thread when the time comes.

I just pulled the trigger on the frame at the LBS, they will place a special order on monday and should have it by the end of the week, so it's actually happening now!

Wheel stuff arrived yesterday, so i've been busy building, and so far the front wheel has come out pretty good while the rear is still in progress in the truning stand. I ended up ordering the Panaracer Pasela 700x38c in stead of 35c as planned, since the 35 was out of stock. After mounting the 38c on the 19mm internal diamter TK 540 rims the tire measured 34,5mm, and after sitting with 50 psi over night, it had stretched to 35,1 mm this morning. The tire sidewalls are surprisingly thin, while the tread seem more sturdy. I wont be riding any gnarly roads, so it will be interresting to see how the sidewalls will wear.

The build spec is still as in the first post, except from the rear derailer where I will be getting the 4700 Tiagra, based on excelent advise given in this thread.
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Old 03-18-17, 09:30 AM   #22
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Quote:
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Thanks, I run a triple on my current commuter, but I want to simplify things and be able to use the 38t ring as the primary chainring. I currently find myself shifting very often between the big and middle ring.

11-34t in the back is noted, it's the reason i'm going with the deore rear derailer, since it will accept the 34t in contrast to the long cage tiagra rear derailer. I'm not all set on gearing yet, I've been thinking 38 was too low as well, but I think i'll try this out and see how it goes.
Going from a triple to a double doesn't really "simplify" anything. You still have a derailer to deal with and all you have is one less chainring and less range.

The lower range brings up the other fly in the ointment. If you are currently shifting between the big and middle ring, it means you are using the gears efficiently. Shifting up and down the gear range isn't a "problem", it's the way you are supposed to use the gears.

Also going to a 38/24 crank leaves giant holes in your shifting pattern as it does for all doubles. This comparison of the 38/24 vs a 46/34/24 crank illustrates the problem.

First, the triple has a wider range so that you don't end up coasting as often. With the double, you end up running out of gears at around 25 mph while the wider triple allows you to pedal for about 10mph more. Running out of gears gets frustrating real fast.

But looking at the shift pattern closely, one of the things that jumps out to me on all doubles is that the transition from the outer ring to the inner ring is large and jarring. Let's say that you are cruising in the 38/19 combination at about 15mph and you feel you need to shift to the inner ring. You'll need to increase your cadence from 90rpm to greater than 120rpm and you won't be close to the cadence you need to maintain the speed. It feels kind of like you've dropped a chain.

On the triple, the step is smaller (although still a bit too large). You only need to increase cadence to 120rpm to maintain the same speed. If you play with the calculator a bit, you can see that a 46/38/24 offers a nice shifting pattern where a change from the outer ring to the middle ring is smaller more natural jump. If you use a 40 tooth middle ring (hard to find), the change from outer to inner is about the same as a change from one cassette cog to the next. I use this on a road triple for my commuter bike and find it a great shifting pattern. A 44/38/24 would be similar but with a bit lower gearing.
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Old 03-19-17, 04:37 AM   #23
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Tire update: the Pasela 38c has now grown from 34,5 to 36mm width since friday evening.

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Originally Posted by cyccommute View Post
Going from a triple to a double doesn't really "simplify" anything. You still have a derailer to deal with and all you have is one less chainring and less range.

The lower range brings up the other fly in the ointment. If you are currently shifting between the big and middle ring, it means you are using the gears efficiently. Shifting up and down the gear range isn't a "problem", it's the way you are supposed to use the gears.
To me it does simplify things, since with the 38t big ring, it will allow me to stay in that ring longer than I am able to stay in the big ring on my current triple before i need to shift to the middle ring, which means a shift between the chainrings has i been eliminated in more cases than with the triple. This is what i mean by simplifying things.

Quote:
Originally Posted by cyccommute View Post
Also going to a 38/24 crank leaves giant holes in your shifting pattern as it does for all doubles. This comparison of the 38/24 vs a 46/34/24 crank illustrates the problem.

First, the triple has a wider range so that you don't end up coasting as often. With the double, you end up running out of gears at around 25 mph while the wider triple allows you to pedal for about 10mph more. Running out of gears gets frustrating real fast.

But looking at the shift pattern closely, one of the things that jumps out to me on all doubles is that the transition from the outer ring to the inner ring is large and jarring. Let's say that you are cruising in the 38/19 combination at about 15mph and you feel you need to shift to the inner ring. You'll need to increase your cadence from 90rpm to greater than 120rpm and you won't be close to the cadence you need to maintain the speed. It feels kind of like you've dropped a chain.

On the triple, the step is smaller (although still a bit too large). You only need to increase cadence to 120rpm to maintain the same speed. If you play with the calculator a bit, you can see that a 46/38/24 offers a nice shifting pattern where a change from the outer ring to the middle ring is smaller more natural jump. If you use a 40 tooth middle ring (hard to find), the change from outer to inner is about the same as a change from one cassette cog to the next. I use this on a road triple for my commuter bike and find it a great shifting pattern. A 44/38/24 would be similar but with a bit lower gearing.
First, as said previously in this thread, I dont mind coasting at 25 mph, it is quite a lot faster than my commuting cruise speed, and I would rather have wider range at the lower end. Should I end up finding it frustrating as you and others are warning me about, I can easily swap the ring for a bigger one.

Secondly, thanks for the link to that gear calculator! Thats a pretty handy tool for comparing gear ranges. Up untill now I've been using Sheldon Browns calculator which is not as good for comparing ranges.

Looking at that comparison, I do see what you're on about and it has got me thinking about getting a 26 or even 28t inner ring for commuting, and then keeping the 24t for when I decide to load the racks up. I do not fully agree with you on the drastic increase in cadence when shifting to the small ring, as I always combine it with one or two shifts to a smaller sprocket, to even out the transition between the chainrings.

This whole project is a result of what I like and dislike about my current commuter. Some of the parts are chosen from actual experience, and some are based on what I think will give the result I'm looking for, so the final result of this build, will not necessarily be the final state of the bike - most likely not.
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Old 03-19-17, 08:24 AM   #24
bradtx
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Originally Posted by masterchief View Post
Tire update: the Pasela 38c has now grown from 34,5 to 36mm width since friday evening...

This whole project is a result of what I like and dislike about my current commuter. Some of the parts are chosen from actual experience, and some are based on what I think will give the result I'm looking for, so the final result of this build, will not necessarily be the final state of the bike - most likely not.
My Panaracer tires were quite a bit wider than other brands of the same listed size, nearly contacting the chain stays. My Cannondale's chain stays are possibly larger in diameter than the Trek's.

There is always something to groom after a couple of tours worth of experience.

Brad
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Old 03-19-17, 08:41 AM   #25
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Quote:
Originally Posted by masterchief View Post
Tire update: the Pasela 38c has now grown from 34,5 to 36mm width since friday evening.



To me it does simplify things, since with the 38t big ring, it will allow me to stay in that ring longer than I am able to stay in the big ring on my current triple before i need to shift to the middle ring, which means a shift between the chainrings has i been eliminated in more cases than with the triple. This is what i mean by simplifying things.



First, as said previously in this thread, I dont mind coasting at 25 mph, it is quite a lot faster than my commuting cruise speed, and I would rather have wider range at the lower end. Should I end up finding it frustrating as you and others are warning me about, I can easily swap the ring for a bigger one.

Secondly, thanks for the link to that gear calculator! Thats a pretty handy tool for comparing gear ranges. Up untill now I've been using Sheldon Browns calculator which is not as good for comparing ranges.

Looking at that comparison, I do see what you're on about and it has got me thinking about getting a 26 or even 28t inner ring for commuting, and then keeping the 24t for when I decide to load the racks up. I do not fully agree with you on the drastic increase in cadence when shifting to the small ring, as I always combine it with one or two shifts to a smaller sprocket, to even out the transition between the chainrings.

This whole project is a result of what I like and dislike about my current commuter. Some of the parts are chosen from actual experience, and some are based on what I think will give the result I'm looking for, so the final result of this build, will not necessarily be the final state of the bike - most likely not.
Did you set the Pasela tubeless?
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