need some advise on replacing road bike drop bar

I don't know of anyone that manufactures a 7-speed TT index shifter...someone else here might know of such a thing. Alfeng, for one.

I have heard of guys cobbling up home made adapters to convert the old downtube 7-speed index shifters to fit aerobars. For a $175-$250 bike it might be a bit of an economic stretch, but if you have no money and plenty of time to dig up the needed components...

I would assume that with the swap to longer shift cables that you could re-mount your existing Revo twist shifters to the aero bars. No clue as to how awkward or handy shifts would be though.

if you don't mind, could you briefly explain this whole indexing business. I've been reading on the subject but haven't made any sense yet..cheers

Quoted post said:

Originally Posted by Sohrab [IMG]/img/forum/go_quote.gif[/IMG]

if you don't mind, could you briefly explain this whole indexing business. I've been reading on the subject but haven't made any sense yet..cheers

never mind there, found a good wiki article.

Quoted post said:

Originally Posted by Sohrab [IMG]/img/forum/go_quote.gif[/IMG]

if you don't mind, could you briefly explain this whole indexing business. I've been reading on the subject but haven't made any sense yet..cheers

Sure, prior to the mid to late '80s bike shifters were just levers that pulled the shift cables and relied on friction to hold the lever in place and thereby hold the cable taut and hold the derailleur in the same gear. At that time bikes typically used 5, 6 or 7 rear cogs with a certain spacing between each cog. When you shifted you pulled or pushed the lever a bit you either tightened or loosened the cable but there were no click stops or definite gear positions so it was up to the rider to change the lever just enough to go to the desired gear and not have the derailleur partway between two gears where it would try to shift up or down, make a bunch of noise, and potentially jump suddenly to the next gear up or down the rear cluster, that or rub against the front derailleur cage. Back then riders would sometimes be told to 'clean your shift' by riding partners who could more easily hear the racket of a poor shifter position and a clattering chain. The levers were typically mounted on the bike's downtube but sometimes the were mounted on either side of the stem or sprouted out of the end of the road bike handlebars as bar end shifters.

Then Shimano and eventually others introduced forms of 'indexed shifting' where the shifters had click stop indents spaced so each click was aligned to move the derailleur (at least the rear derailleur) one full gear. If properly installed and maintained this results in clean shifts and no midway shifting. When out of adjustment with too tight or too loose of a cable the indexing on the shifter won't align well with the rear derailleur and the cogs and some or all gears will be noisy and not clean shifts. Most early indexed shifters whether bar end or downtube mounted could be run in either an indexed mode with the click shifts or in a friction mode by spinning a small 'knob' on the shifter body so if your indexing got out of whack you could always swap to friction mode and manually make and clean your shifts.

Over the years manufacturers introduced 8, 9, 10, and now 11 speed drive trains which changed the spacing between cogs and required different indexed shifters though if you can find them friction shifters still work as they don't depend on particular cog spacing.

Around the time manufacturers introduced 8 speed systems they also started offering integrated brake/shifters which only work in indexed mode and don't allow a change to friction mode.

Good luck,
-Dave

cheers mate, thank you for the info...

No worries, but I didn't read your post carefully enough and from your title thought you were going with flat bars, not TT bars.

For aero extensions you'll want to find either an old set of friction only bar end shifters or you can use any bar end shifter that can be switched into friction mode which is most of them except the newest and most expensive return to center (R2C) designs.

ebay is your friend for something like these: http://www.ebay.com/sch/i.html?_nkw=+bar+end+shifters&_sacat=0&_odkw=7+speed+bar+end+shifters&_osacat=0 just make sure they support friction mode.

-Dave

you'll have to forgive what may seem ignorant questions, I am new to this...

you may know what the GMC Denali 700 looks like: http://i.walmartimages.com/i/p/00/01/67/51/92/0001675192706_500X500.jpg

so, the break leavers and the shifters are all attached to the handle bar. I wish to replace the handle bar the bike came with with this one or at least one that looks like this:

http://www.profile-design.com/profile-design/products/base-bars/carbon-base-bars/svet.html

I also want to attach an aerobar there, something like this:

http://www.profile-design.com/profile-design/products/aerobars/aluminum-aerobars/zbs-s-bend.html

so, what you are saying is that I need to get shifters that support friction mode (the ones you kindly shared the link to) along with new break leavers/cables and then I should be good to go?

I appreciate the info, however I am trying to make sense of it all in terms of a step by step solution 🙂

cheers

Yes, you 'could' swap your front end by purchasing the components you've listed along with a set of seven speed or friction compatible bar end shifters and a set of compatible brake (not break) levers such as: http://www.ebay.com/itm/2-TEKTRO-TIME-TRIAL-TRIATHLON-BAR-END-AERO-BRAKE-LEVERS-/290713082485?pt=Cycling_Parts_Accessories&hash=item43afd99a75
But whether you 'should' do that is a different question.

Are you trying to set up a fast and aerodynamic Time Trial or Triathlon bike? If so your next issue will be fitting yourself to a good position that allows you to utilize those fancy aero bars with a relatively low front end. That's tough to do when retrofitting a road bike as neither the seat tube angle nor top tube length are designed for riding aggressive and low time trial positions. You can get close by using an aftermarket seat post such as the Fast Forward style like this: http://www.profile-design.com/profile-design/products/seatposts/aluminum-seat-posts and then using an appropriate stem (likely shorter than your existing road stem) to achieve a fast and functional fit. But if you do so you'll be putting a lot more weight on the front end of your road bike than was intended by the frame designer and that can negatively impact handling. If you don't go too crazy forward and steep with the seat angle you should be fine but then you won't be able to set up as low and aero a position in the front unless you're very flexible and can sustain good riding power at very tight leg and hip angles in the aero position but most folks can't and need steep seat angles to get real low.

Time trial and tri bikes are designed a bit differently than road bikes such that they handle nicely even with steep seat tube angles and low and forward riding positions. You can certainly convert a road bike but you may not be pleased with the results.

If you're going to aero bars but intending to ride them higher in a less aggressive comfort position and not going after a super low front end then you'll be fine and can stay with your normal seat post but don't try to put the bars too low and you may need to flip your stem or go to a higher rise stem to make sure your angles stay sufficiently open at slacker seat angles.

Either way, even with just the bars and extensions you've listed, a set of bar end shifters and aero bar brake levers plus new cables and housings which you'll need to set the bike up you'll be more than doubling the retail price of that bicycle. Changing those front end parts will cost a lot of money but won't help the fact the bike is equipped with entry level components including entry level wheels and no doubt an entry level frame.

Whether this project is worth doing is up to you of course but like a lot of folks I've been down the 'upgrade an entry level bike' path and it's a good way to drop a lot of money without being happy with the outcome. Personally I'd take whatever money you were going to put into a new front end and shop around for a good deal on a used steel or aluminum triathlon or Time Trial bike as they're really easy to come by. Check out your local Craigslist so you can actually see and test ride the bike but you can likely find a complete bike for about the same as this project will cost you and it will likely be a better bike.

If you're really not after a fast time trial or triathlon bike and really want to do this project then I'd skip the carbon bars and buy some inexpensive alloy base bars like: http://www.ebay.com/itm/Profile-Design-T2-Wing-Alloy-Base-bar-31-8-420mm-USED-/160866748546?pt=Cycling_Parts_Accessories&hash=item257467c882
At least that keeps the cost down.

If you really want to keep it simple and save cash it's possible to remove your bar tape and existing shifters (don't cut or remove any cables just let them dangle), remove the handlebars, flip them upside down so the drops are pointing up and the bar ends are above the stem. Use a hacksaw or pipe cutter to cut the drops off the handlebars until they're urban fixie style home made cowhorn bars. Remount the brake/shifters to with their bar clamps very near the end of the fresh cut cowhorns, recable by trimming housings if necessary then add some clip on aero extensions.

With that setup you'll still use your existing brakes and existing shifters. The shifters will be mounted on the cowhorn bar ends and a bit less convenient while riding in the aero bar position. Unless you decide to change stems for fitting purposes you'll use all the same parts and not buy a new base bar, new shifters or new brake levers. The process is something like this: http://www.commutebybike.com/2006/11/11/how-to-make-your-own-bull-horn-handle-bars/

That won't solve any problems with seat angle or bike handling in really low aero positions but it does give you an aero bar setup with cowhorns for a lot less cash and reuses all your existing parts.

Good luck,
-Dave